HK1166189A - Power converter with automatic mode switching - Google Patents

Description

Power converter with automatic mode switching

This application claims priority from U.S. patent application No.12/370,488, filed 2/12/2009, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to an electronic apparatus and a power converter circuit for the electronic apparatus.

Background

Alternating Current (AC) power is typically provided from a wall outlet and is sometimes referred to as line power. Electronic devices include circuits that operate from Direct Current (DC) power. The power converter circuit is used to convert AC power to DC power. The DC power generated in this manner can be used to power electronic devices. The generated DC power may also be used to charge a battery in the electronic device.

In some applications, the AC-to-DC power converter circuit may be incorporated into an electronic device. For example, desktop computers often include AC-to-DC power converter circuits in the form of computer power supply units. The computer power supply unit has a receptacle that receives an AC power cord. With this type of arrangement, the AC power cord can be plugged directly into the back of the computer to provide AC power without the use of an external power converter.

While desktop computers are large enough to accommodate internal power sources, other devices such as handheld electronic devices and portable computers do not. Thus, typical handheld electronic devices and laptop computers require the use of an external power converter. When separate from the power converter, the handheld electronic device or portable computer may be powered by an internal battery. When AC line power is available, the power converter is used to convert the AC power to DC power for the electronic device.

The design of compact AC-DC power converters is generally based on a switched-mode power supply architecture. Switched mode power converters incorporate switches, such as transistor-based switches, that work with energy storage components, such as inductive and capacitive elements, to regulate the generation of DC power from an AC source. The feedback path may be used to tap into the output of the converter and thereby ensure that the desired DC voltage level is produced under varying loads.

High power converter efficiency is desirable for power saving. High power conversion efficiency can be achieved by using efficient converter topologies and low loss components. However, even when an optimal design is used, there is a residual power loss when operating the power converter. These residual losses are associated with leakage currents and other parasitics due to the switched mode circuitry that operates the converter, and result in power consumption by the power converter even when the power converter is not actively used to power the electronic device. The power consumption when the power converter is not used to power the electronic device represents a source of undesirable power losses that can be reduced without adversely affecting the functionality of the converter.

Disclosure of Invention

A power converter may be provided that includes an energy storage circuit. The power converter may receive an input signal, such as a line power signal, and may generate a corresponding output signal, such as a power signal for a device or other circuitry. The power converter may be set to a standby mode to save power. In the standby mode, the energy storage circuit may be used to power circuits that may wake up the power converter from the standby mode when appropriate. The power converter circuit may be provided as part of a stand-alone power adapter or may be incorporated into other electronic devices.

With one suitable arrangement, the power converter may be a power converter circuit such as an Alternating Current (AC) to Direct Current (DC) switched mode power converter circuit. The power converter circuit may convert AC line power to DC power for powering the attached electronic device. For example, the power converter may be used to power an electronic device such as a cellular telephone, a portable computer, or a music player.

The power converter circuit may have a switch modulated to control the flow of power. When the switch is open, the power converter circuit is substantially off and will not generate DC power at its output. In this state, sometimes referred to as a standby mode or sleep mode, the power consumption of the power converter is minimized. When it is desired to power the attached electronic device, the power converter circuit may operate in an active mode, in which the switch is actively modulated to produce a desired output signal (e.g., a DC output voltage).

The power converter circuit may provide its output to the output line through the switching circuit. In normal operation, the monitor circuit sets the switching circuit to a closed state in which the power converter circuit is coupled to the output line and generates a DC output voltage for powering the electronic device. The monitor may periodically open the switching circuit to isolate the power converter circuit from the output line. The behaviour of the voltage on the output line can be monitored by a monitor. In the presence of a load drawing power, the output line voltage will tend to drop. When driven by an internal boosting circuit (boost circuit) when no load is present, the output line voltage may rise (or may at least not fall below a given threshold). If the voltage on the output line rises (or does not fall below a given threshold), the monitor may conclude that the electronic device is disconnected from the power converter. If the voltage on the output line drops (or drops beyond a given threshold), the monitor may conclude that the electronic device is attached to the power converter.

The power converter may include an energy storage element such as a capacitor or a battery. The monitor may draw power from the energy storage element when the power converter circuit is operating in the standby mode. This enables the monitor to actively monitor the state of the output line to automatically determine when the electronic device is reattached to the power converter. The monitor may also monitor the state of the energy storage element. If the energy storage element is depleted, the monitor may instruct the power converter circuit to temporarily transition from the standby mode of operation to the active mode of operation to replenish the energy storage element. If a drop in the output line voltage is detected indicating that the electronic device is reattached to the power converter, the monitor may activate the power converter circuit so that the electronic device may be powered.

Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.

Drawings

Fig. 1 is a circuit diagram of a system including a power converter and an electronic device according to an embodiment of the present invention.

Fig. 2 is a circuit diagram showing illustrative components that may be used in a power converter of the type shown in fig. 1, according to an embodiment of the invention.

FIG. 3 is a graph showing how the output voltage from a power converter of the type shown in FIG. 2 may develop when an electronic device is disconnected from the power converter, according to an embodiment of the present invention.

Fig. 4 is a graph showing how the voltage across an energy storage element in a power converter of the type shown in fig. 2 may develop during standby mode operation and energy replenishment operation, according to an embodiment of the present invention.

FIG. 5 is a graph showing how the output voltage from a power converter of the type shown in FIG. 2 may develop when an electronic device is attached to the power converter, according to an embodiment of the present invention.

Fig. 6 is a graph showing how the output voltage from a power converter of the type shown in fig. 2 may develop during a monitoring operation when an electronic device powered by the power converter remains attached to the power converter, according to an embodiment of the invention.

Fig. 7 is a diagram showing operations involved in an illustrative mode of operation and transitioning between modes of operation in a power converter of the type shown in fig. 2, according to an embodiment of the present invention.

FIG. 8 is a diagram of an electronic device showing how a monitor circuit may be powered by an energy storage circuit to detect a power change in a power cord in the electronic device, according to an embodiment of the invention.

Fig. 9 is a diagram of an electronic device showing how a monitor circuit powered by an energy storage circuit may be used to wake up a power supply in an electronic device that has been set to a standby mode, according to an embodiment of the invention.

FIG. 10 is a diagram of an electronic device having first and second power sources, showing how a monitor circuit powered by an energy storage circuit may be used to control the first and second power sources, according to an embodiment of the invention.

FIG. 11 is a diagram of an illustrative power adapter housing configuration that may be used with a power adapter circuit of the type shown in FIG. 1, according to an embodiment of the present invention.

FIG. 12 is a diagram of an illustrative power adapter housing configuration that may be used with a power adapter circuit of the type shown in FIG. 1 and that may have a magnetic attachment mechanism, according to an embodiment of the present invention.

FIG. 13 is a diagram showing how a power converter circuit output capacitor may be used as an energy storage device to power a monitor circuit, according to an embodiment of the invention.

Detailed Description

Power converters, sometimes referred to as power adapters, are used to convert power levels and types. For example, power converters may be used to raise or lower a Direct Current (DC) power level. Power converters may also be used to convert Alternating Current (AC) power to DC power. Power converters for converting AC power to DC power are sometimes described herein as examples. In general, however, the power converter circuit may include circuitry for converting any suitable input signal (e.g., AC or DC current and voltage) to any suitable output signal (e.g., raised, lowered, or otherwise converted AC or DC current and voltage). The use of a power converter, such as an AC-DC power converter that produces a regulated DC output voltage from an AC input signal, is merely illustrative.

In a typical scenario, the power converter may be plugged into an AC line power source, such as a wall outlet. The AC power source may provide 120 volts or 240 volts of power (as examples). Circuitry in the power converter may convert the received AC line power to DC power. For example, an AC-DC power converter may receive AC line power at an input and may provide DC power at a corresponding output. The output voltage level may be 12 volts, 5 volts, or any other suitable DC output level.

The circuitry in the power converter may be based on a switched-mode power supply architecture. Switched mode power supplies implement power conversion functions in relatively compact circuits using, for example, switches and associated control schemes, such as pulse width modulation control schemes or frequency modulation control schemes, for example, metal oxide semiconductor power transistors. When the switching circuit has the first configuration, power is transferred from the power source to a storage element, such as an inductor (e.g., a transformer) or a capacitor. When the switching circuit has the second configuration, power is discharged from the storage element to the load. Feedback may be used to regulate the power transfer operation and thereby ensure that the output voltage is maintained at a desired level. Examples of switched-mode power supply topologies that may be used in a power converter include buck converters, boost converters, flyback converters, and the like.

With one suitable arrangement, described herein as an example, an AC-DC power converter may be implemented with a voltage rectifier and a flyback converter. The voltage rectifier converts the AC line power to DC power at a relatively high voltage level. While the flyback converter portion of the power converter steps down the DC power to 12 volts, 5 volts, or other suitable low level at the output of the rectifier circuit to operate the circuitry in the electronic device. Other power converter architectures may be used if desired. The use of a switched mode power converter arrangement based on a flyback converter design is described herein as an example.

The AC-DC power converter may provide DC power to any suitable electronic device. Examples of electronic devices that may receive DC power from an AC-DC power converter include handheld computers, miniature or wearable devices, portable computers, desktop computers, routers, access points, backup storage devices with wireless communication capabilities, mobile phones, music players, remote controllers, global positioning system devices, and devices that combine the functionality of one or more of these devices. With one suitable arrangement, sometimes described herein as an example, the electronic device receiving DC power from the AC-DC power converter is a compact, portable device, such as a handheld electronic device (e.g., a mobile phone or a music player). However, this is merely illustrative. The AC-DC power converter may operate with any suitable electronic device.

An illustrative system environment in which a power converter may provide power to an electronic device is shown in fig. 1. As shown in fig. 1, system 8 may include an AC power source, such as AC power source 14, a power converter, such as AC-DC power converter 12, and an electronic device, such as electronic device 10.

The AC power source 14 may be, for example, a standard wall outlet that provides AC line power via a power cord. Wall outlet power is typically delivered at an AC voltage of about 110 volts to 240 volts.

Power converter 12 may include a power converter circuit such as AC-DC power converter circuit 122. AC-DC power converter circuit 122 may be based on a switched-mode power supply design, such as a flyback converter or other suitable power converter topology.

Electronic device 10 may have a battery for powering device 10 when not attached to power converter 12. When power converter 12 is plugged into AC power source 14 and when electronic device 10 is connected to power converter 12, power converter 12 may convert AC power received from AC power source 14 to DC power for device 10.

Connectors may be provided at the input and/or output of power converter 12, if desired. For example, device 10 may have a Universal Serial Bus (USB) port into which a USB cable may be plugged. The USB cable may be used to transfer DC power between power converter 12 and electronic device 10. For example, a USB cable or other cable may include a first line, such as positive power line 72, for conveying a positive DC voltage of 12 volts, 5 volts, or other suitable positive DC voltage level from converter 12 to device 10. This DC voltage level is sometimes referred to as Vbus, and line 73 of converter 12 is sometimes referred to as the power bus or output line. The USB cable or other cable may also have a second line, such as ground line 74, for transmitting a ground voltage of 0 volts or other suitable ground voltage level to device 10. A cable such as a USB cable may also contain data lines that may optionally be used to transfer information between device 10 and converter 12.

When connected to power converter 12, electronic device 10 may receive DC power through the power pins and cables of the USB connector (as an example). However, the use of a USB connector to connect power converter 12 and electronic device 10 is merely illustrative. Any suitable plug, socket, port, pin, other connector, or hardwired connection may be used to interconnect power converter 12 and electronic device 10, if desired. Similarly, a hardwired connection or a suitable plug, receptacle, port, pin structure, or other connector may be used to connect power converter 12 to power source 14.

AC-DC power converter circuit 122 may convert AC power from AC source 14 to DC power on output paths 64 and 70. Path 64 may be a positive power supply line coupled to converter output line 73 via switch SW 2. Path 70 may be a ground power line coupled to ground output 75 of converter 12 and ground line 74 in a cable or other path connecting converter 12 to device 10. The switching circuitry, such as switch SW2, may be based on any suitable electrical component that may control the flow of DC power from the output of AC-DC power converter circuit 122 to a power input line associated with electronic device 10 (e.g., the input of device 10 connected to power lines 72 and 74). For example, switching circuit SW2 may be implemented using one or more transistors, such as one or more power field effect transistors (power FETs). During normal operation, where an electronic device, such as electronic device 10, is connected to power converter 12, power converter 12 may provide a DC supply voltage on lines 64 and 70 using AC-DC power converter circuit 122. The switching circuit SW2 is normally closed during normal operation, so line 64 will be shorted to output line 73. This allows the DC supply voltage of the output of AC-DC power converter circuit 122 to be provided to the electronic device via paths 72 and 74.

AC-DC power converter circuit 122 may include control circuitry for controlling the internal switching circuitry. The control circuit may be responsive to a feedback signal. For example, the feedback path may be used to provide information to AC-DC power converter circuit 122 regarding the current level of voltage Vbus on output line 73. In response to such feedback information, the control circuitry in AC-DC power converter circuit 122 may make real-time adjustments to the amount of DC voltage provided to the AC-DC power converter circuit output. For example, if the DC voltage on output 64 has a nominal value of Vsec of 5 volts and the feedback indicates that the voltage has undesirably risen to 5.05 volts, the control circuitry in AC-DC power converter circuit 122 may make adjustments to reduce the DC output voltage back to the nominal value (Vsec).

Power converter 12 may include an energy storage circuit 50. The energy storage circuit 50 (also sometimes referred to as an energy storage element) may be based on any suitable circuitry for storing energy. By way of example, the energy storage circuit 50 may include one or more batteries, capacitors, and the like. During operation of power converter 12 when AC-DC power converter circuit 122 provides power to output path 64, a path such as path 66 may be used to transfer power to energy storage circuit 50. The power delivered to the energy storage circuit 50 in this manner may be used to supplement a battery, capacitor, or other energy storage component in the circuit 50. In the example of fig. 1, energy storage circuit 50 is coupled to AC-DC power converter circuit 122 by paths 64 and 66. However, this is merely illustrative. Any suitable transmission path may be used to provide supplemental power from AC-DC power converter circuit 122 to energy storage circuit 50, if desired.

As shown in fig. 1, power converter 12 may include a monitoring circuit such as monitor 54. Monitor 54 may monitor the state of power converter 12 using paths such as paths 66 and 60. Monitor 54 may provide control signals to AC-DC power converter circuit 122 using a path such as path 76, when appropriate. The control signal may be used to set the AC-DC power converter circuit into an appropriate operating mode. In general, any suitable number of operating modes may be supported by AC-DC power converter circuit 122, if desired.

With one suitable arrangement, sometimes described herein as an example, AC-DC power converter circuit 122 may be set to an active mode and a standby mode. In an active mode, also sometimes referred to as a high power mode or normal operating mode, AC-DC power converter 122 is on and provides DC output power for replenishing energy storage circuit 50 and for powering electronic device 10. In a standby mode, sometimes referred to as a sleep mode or a low power mode, AC-DC power converter circuit 122 is set to a state in which AC-DC power converter circuit 122 consumes little or no power (i.e., AC-DC power converter circuit 122 is turned off by inhibiting modulation of its switching mode power switch). AC-DC power converter circuit 122 may have multiple low power states (e.g., a partially off state and a fully off state), if desired. Arrangements in which AC-DC power converter 122 is set to a standby state or an active state are described herein as examples. However, this is merely illustrative. In general, power converter 12 may support any suitable number of operating modes (e.g., full on mode, partial on mode, sleep mode, deep sleep mode, etc.).

When AC-DC power converter circuit 122 is in the standby mode, AC-DC power converter circuit 122 is turned off and output 64 is allowed to float. In this case, the power that has been stored in energy storage circuit 50 may be delivered from energy storage circuit 50 to path 66. For example, if energy storage circuit 50 contains a battery or capacitor, the battery or capacitor may be used to provide a battery or capacitor voltage to path 66. The voltage provided by energy storage circuit 50 may be provided at the same voltage level as the nominal output voltage level (Vsec) that AC-DC power converter circuit 122 provides to path 64 when AC-DC power converter circuit 122 is in the active mode.

Voltage regulator 66 may receive a voltage at its input IN provided by energy storage circuit 50 via path 66, and may provide a corresponding output voltage to output path 58 via its output OUT. In the absence of a load on output line 73, the voltage provided by voltage regulator 52 to path 58 may be elevated relative to Vsec (i.e., the voltage provided by voltage regulator 52 to path 58 during standby operation may be equal to an elevated voltage Vaux that is greater than Vsec). For example, if Vsec is 5.0 volts (as an example), Vaux may be 5.1 volts (as an example).

Output line 58 may be coupled to output line 73 and path 72 by path 56. During standby mode, monitor 54 may provide a switching control signal to switching circuit SW2 via a path such as path 62. The control signal may place SW2 in an open mode, wherein lines 64 and 73 are electrically disconnected from each other. Disconnecting output line 73 from path 64 isolates output 73 from AC-DC power converter circuit 122 and energy storage circuit 50. The voltage that output line 73 presents after monitor 54 opens switching circuit SW2 depends on the state of electronic device 10.

If electronic device 10 is disconnected from power converter 12 while switching circuit SW2 is open, voltage regulator 52 will provide a boosted voltage Vaux to output line 73 via paths 58 and 56, thereby driving Vbus to Vaux. If electronic device 10 is connected to power converter 12 while monitor 54 opens switching circuit SW2, electronic device 10 will operate as a load and will draw power from the output OUT of the voltage regulator via lines 58 and 56. Voltage regulator 52 may contain a current limiting circuit that ensures that voltage regulator 52 will only be able to provide a relatively modest amount of current to electronic device 10. Thus, the power drawn from electronic device 10 will pull Vbus low.

Monitor 54 may determine the attachment status of electronic device 10 by monitoring voltage Vbus on output line 73 via paths 56 and 60. If the monitor detects a rise in voltage Vbus when switching circuit SW2 is open, monitor 54 may conclude that electronic device 10 is presently disconnected from power converter 12. If monitor 54 detects a drop in voltage Vbus when switching circuit SW2 is open, monitor 54 may conclude that electronic device 10 is presently attached to power converter 12. Whenever monitor 54 determines that electronic device 10 is attached to power converter 12, monitor 54 may set AC-DC power converter circuit 122 to an active mode to power device 10. If the presence of electronic device 10 is not detected, monitor 54 may leave the AC-DC power converter circuit in a standby mode to conserve power. If monitor 54 detects that energy storage circuit 50 has been depleted due to prolonged operation in the standby mode, monitor 54 may temporarily wake up AC-DC power converter circuit 122 to replenish energy storage circuit 50.

Power converter 12 of fig. 1 may be implemented using any suitable circuitry. An illustrative circuit that may be used to implement power converter 12 is shown in fig. 2. In the example of fig. 2, power converter circuit 122 is formed using a flyback switched mode power supply design. However, this is merely illustrative. Any suitable power converter circuit may be used for AC-DC power converter circuit 122, if desired.

As shown in fig. 2, AC source 14 may be coupled to power converter 12 at terminals L and N. AC power from terminals L and N may be provided to paths 20 and 22.

Power converter 12 may have a rectifier circuit 16. Diode 18 may convert the AC voltage on paths 20 and 22 into a rectified (positive) signal across lines 24 and 26. The AC voltage on paths 20 and 22 may be sinusoidal and the output of rectifier circuit 16 may be a rectified sinusoidal. To smooth the raw rectified output from diode 18, power converter 12 may include a capacitor 28. Capacitor 28, which may be considered part of rectifier 16, converts the rectified version of the AC signal from source 14 into a DC voltage on node 30 with a reduced amount of AC ripple.

AC-DC power converter circuitry 122 may include power converter control circuitry such as converter control circuitry 38. Ground line 56 may be used to connect the converter control circuit to ground path 24. The positive supply voltage Vb may be provided to converter control circuit 38 at input 84. By tapping the power line 26 with the bleeder circuit 82, the input 84 may have a voltage Vb. Bleeder circuit 82 may include a current limiting component such as one or more resistors.

The transformer 32 may have an input connected to the output of the rectifier 16 and an output connected to the diode 40 and the capacitor 42. The transformer 32 may have a turns ratio, such as a 10: 1 or 20: 1 turns ratio. A switching circuit SW1, such as a bipolar or mos power transistor, may be used to regulate the current Ip flowing through the primary side of the transformer 32. Switch SW1 may receive a control signal from converter control circuit 38 at control input 36. The control signal may have a frequency of about 20kHz to 100kHz (as an example). Control circuitry 38 may generate control signals on lines 36 that regulate the flow of power through converter 12. When power converter 12 operates in the active mode, the control signal is active and is varied as needed to regulate the magnitude of voltage Vbus. When power converter 12 is in the standby mode, the control signal is inactive (i.e., no time-varying control signal is present on line 36). This reduces power consumption in power converter 12 that would otherwise be caused by operation of switching circuit SW1, even in the absence of a connected load on output line 73. Standby power consumption may be further reduced by opening optional switching circuits (e.g., switches SW3 and SW4) to reduce leakage current (e.g., using control signals from converter control circuitry 38 and/or from monitor 54).

The control signal provided on line 36 to switching circuit SW1 may be a signal whose frequency is adjusted to control the amount of power flowing through the converter or may be a signal such as a Pulse Width Modulation (PWM) signal whose duty cycle is adjusted to control the amount of power flowing through the converter according to a pulse width modulation scheme.

With a typical PWM scheme, the control signal on line 36 may have a high value when it is desired to turn on switch SW1 to allow current Ip to flow, and the control signal on line 36 may have a low value when it is desired to turn off switch SW1 to prevent current Ip from flowing. The control signal on line 36 may be, for example, a square wave PWM signal whose duty cycle may be adjusted by control circuit 38 to adjust the magnitude of Vbus on output 73. A frequency modulation scheme may be used if desired. In a frequency modulation scheme, the control signal on line 36 may be a square wave or other control signal whose frequency is adjusted by control circuit 38 to adjust the magnitude of voltage Vbus. The use of PWM control signals in power converters, such as power converter 12, is sometimes described herein as an example. However, the use of a PWM signal is merely illustrative. Any suitable type of control signal may be used to control the flow of power in converter 12, if desired.

When control circuit 38 applies a control signal, such as a PWM control signal, to switch SW1, current Is on the secondary side of transformer 32 will have a frequency equal to the frequency of the control signal (e.g., approximately 20kHz to 100 kHz). Diode 40 and capacitor 42 convert the AC signal to a DC voltage at node 44. This voltage is provided to line 64 and represents the output of AC-DC power converter circuit 122 of fig. 1. The nominal power supply output voltage on line 64 (sometimes referred to herein as Vsec) may be, for example, 12 volts, 5 volts, or other suitable voltage. When electronic device 10 is connected to output line 73 during the active mode, the voltage generated at output 64 may be communicated to electronic device 10 via switching circuit SW2, output 73, and path 72 to power the circuitry of electronic device 10.

Power converter 12 may be controlled using an open loop control scheme. With this type of arrangement, power converter 12 may apply a predetermined PWM signal, frequency modulation signal, or other control signal to switching circuit SW1 to produce a desired output level on output 64 and output line 73. If desired, a closed loop control scheme may be used by providing a feedback path FB, such as the feedback path formed by lines 48 and 49. Control circuit 38 may receive feedback of the current voltage level across nodes 44 and 46 (i.e., the output voltage on line 64) using lines 48 and 49. If the currently monitored value of the output voltage on node 44 is below the desired target level (i.e., below the desired Vsec level), the duty cycle of the PWM signal, or the frequency of the control signal in the frequency modulation scheme, may be increased to increase the output voltage accordingly. If control circuit 38 determines that the output voltage on output 64 and node 44 of AC-DC power converter circuit 122 is too high, the duty cycle of the PWM signal or the frequency of the control signal may be decreased to decrease the output voltage toward its desired target level.

Circuitry such as converter control circuitry 38 may be located on the primary side of transformer 32. Circuits such as the monitor circuit 54, the energy storage element 50, the switching circuit SW2 and the voltage regulator 52 may be located on the secondary side of the transformer 32. If desired, an isolation stage, such as isolation stage 51, may be included in feedback path FB to help electrically isolate the circuits of the primary and secondary sides of transformer 32. Similarly, an isolation stage, such as isolation stage 78, may be included in control path 76 between supervisory controller 54 and converter control circuit 38. The isolation stages 51 and 78 may be formed by signal transformers, optical isolation devices, and the like.

As shown in fig. 2, the energy storage circuit 50 may be formed of an energy storage element such as a capacitor 80. Capacitor 80 may be coupled between path 66 and ground (e.g., node 46). During standby operation, the capacitor 80 may be used to power the monitor 54 and the voltage regulator 52. Monitor 54 may monitor the output voltage on path 66 from capacitor 80 to determine when capacitor 80 is sufficiently depleted to require replenishment. When replenishment of capacitor 80 energy is desired, monitor 54 may issue a wake-up control signal to converter control circuitry 38 via control path 76. In response, converter control circuit 38 may transition to the active mode by resuming generation of the control signal on control line 36. This will result in the generation of a DC output voltage on line 64 which can be transmitted via path 66 to capacitor 80 to recharge capacitor 80. When the battery-based energy storage elements are depleted, they may also be recharged in this manner. The battery-based energy storage element 50 may have, for example, a charging circuit connected between path 66 and the battery.

Voltage regulator circuit 52 may be formed from a DC-DC power converter, such as DC-DC boost converter 52A, and a current limiting circuit, such as current limiting circuit 52B. The current limiting capability of current limiting circuit 52B may be combined with the voltage regulating capability of power converter circuit 52A, if desired. In the example of fig. 2, the voltage regulation and current limiting functions are implemented using separate circuits. This is merely illustrative. The circuitry, such as power converters 52A and 52B, may be formed from one, two, or more than two integrated circuits and, if desired, may include discrete components.

Power converter 52A may be, for example, a switched mode power supply for a boost circuit formed by control circuitry (e.g., control circuitry 38), a storage element (capacitor and/or inductor), and other components (e.g., diodes). electronic components such as these may be implemented as part of a single integrated circuit, hi operation, boost converter 52A may receive power (e.g., DC voltage Vstore from capacitor 80) on input IN and may provide a corresponding output voltage on output OUT, the output voltage on output OUT of power converter 52A may be lower or higher than voltage Vstore, IN the example of fig. 2, converter 52A is a boost converter that produces a nominal output voltage Vaux on output OUT, where Vaux is greater than the nominal output voltage vsec produced on output 64 of power converter circuit 122. for example, if Vsec is 5.0 volts, Vaux may be 5.1 volts (as an example). The voltage Vstore can range from 5.0 volts when the capacitor 80 is fully charged to a lower value (e.g., a voltage in the range of about 1-4.5 volts) when the capacitor 80 is depleted.

Current limiting circuit 52B may be implemented with one or more resistors or other suitable circuitry for limiting the maximum amount of current that may be drawn from power converter 52A when a load is connected to output line 73.

When power converter circuit 122 is in the standby mode, switch SW2 will be open. In the absence of a load on output line 73, current limiting circuit 52B may pass the voltage on output OUT of boost converter 52A to line 58, which voltage varies in magnitude negligibly. In this case, if the rated output voltage from the boost converter 52A is Vaux, the DC voltage Vbus on the output line 73 will rise to Vaux.

When a load, such as electronic device 10, is connected to power converter 12, the voltage Vbus on output line 73 will be pulled low. In this case, boost converter 52A will not be able to maintain Vbus at Vaux because current limiting circuit 52B is used to limit the amount of current that can be provided to device 10. This causes the voltage Vbus to drop under load.

Therefore, monitor 54 can monitor the attachment state of electronic device 10 by measuring voltage Vbus and observing the change occurring in Vbus while controlling switching circuit SW 2.

Fig. 3 shows how the voltage Vbus on output line 73 develops when the user disconnects the electronic device from power converter 12. At a time prior to t0, electronic device 10 is attached to power converter 12 and receives DC power on lines 72 and 74. Power converter circuit 122 is in active mode and provides a DC output voltage at nominal output voltage Vsec on output 64. Switching circuit SW2 is closed during active mode so voltage Vsec on output 64 of power converter circuit 122 is passed to power converter output line 73. Thus, at a time prior to t0, the voltage Vbus on line 73 is equal to Vsec. At time t0, the user disconnects the electronic device 10 from the output line 73. Voltage Vbus is maintained at voltage Vsec because output line 73 is coupled to output 64 and output 64 provides voltage Vsec. At time t1, monitor 54 opens switching circuit SW2 to isolate output line 73 from power converter circuit 122. The monitor 54 may open the switching circuit SW2 once every few seconds or every few minutes or at other suitable times in this manner in order to check the attachment state of the electronic device 10.

At a time after time t0, electronic device 10 is no longer attached to output line 73. Therefore, when the switching circuit SW2 is opened at time t1, the electronic apparatus 10 no longer supplies a load to the output line 73. This causes Vbus to rise to the level of voltage Vaux, which is provided at the output OUT of voltage regulator 52, as indicated by the ramp segment 87 of curve 86. Monitor 54 may monitor this rise in voltage Vbus using path 60. When a predetermined threshold voltage, such as threshold voltage Vth2, is reached at time t2, monitor 54 may conclude that electronic device 10 has been removed from power converter 12. Thus, monitor 54 may issue a power-down command to power converter circuit 122 over control path 76 to place AC-DC power converter circuit 122 and power converter 12 in a standby power consumption mode. In this mode, the switching circuit SW2 remains open, and thus the voltage Vbus may rise to Vaux at time t between times t2 and t 3.

Line 88 in the graph of fig. 4 shows how the voltage Vstore on path 66 of the output of capacitor 80 may develop over time when electronic device 10 is disconnected from power converter 12. At time ti, power converter 12 is in a standby mode. In standby mode, power converter circuit 122 is off (i.e., switch SW1 is not actively being switched) and monitor 54 is powered by the energy stored in capacitor 80. Initially, at time ti, capacitor 80 has a voltage Vstore of Vsec (i.e., the nominal output voltage on output 64 generated by power converter circuit 122 when power converter circuit 122 is active).

During times ti through td, monitor 54 is operative to detect a change in the attachment state of electronic device 10. This consumes power and energy drains the capacitor 80, causing the voltage Vstore to drop from Vsec to Vth4, as indicated by curve segment 90.

At time td, Vstore falls below a predetermined threshold voltage Vth 4. When monitor 54 detects that Vstore has fallen below Vth4, monitor 54 may issue an activate control command on path 76 that turns on power converter circuit 122. Once the power converter circuit 122 is set to the active mode at time td, the output voltage on output 64 will rise to the nominal output value Vsec, as indicated by segment 92 of curve 88.

Monitor 54 may monitor the replenishment process represented by segment 92 to confirm when Vstore returns to its fully charged state or may indicate that power converter circuit 122 remains active for a given period of time (e.g., a period of several seconds sufficient to recharge capacitor 80). At time tr, after capacitor 80 is replenished, monitor 54 may place power converter circuit 122 in a standby mode. The depletion process of line segment 90 repeats, as indicated by line segment 94. Monitor 54 may turn power converter circuit 122 on and off for a desired length as shown in fig. 4 (i.e., until electronic device 10 is attached).

The diagram of fig. 5 shows how voltage Vbus may develop during the attachment of electronic device 10 to power converter 12. At time ts, electronic device 10 is not attached to power converter 12. In the absence of a load on output line 73, voltage Vbus rises to Vaux to match the no-load output voltage of voltage regulator 54, as indicated by segment 98 of curve 96. At time ta, a user attaches electronic device 10 to power converter 12 (e.g., by connecting a USB cable or other cable between device 10 and power converter 12). Once the device 10 is connected to the output line 73, the device 10 begins to act as a load on the output line 73.

Current limiting circuit 52B prevents voltage regulator 52 from providing a sufficient amount of current required by electronic device 10. This causes the voltage Vbus to drop from Vaux at time ta to a predetermined threshold voltage, e.g., Vth3, at time tb, as indicated by the segment 100. When monitor 54 detects that voltage Vbus has dropped to Vth3, monitor 54 may conclude that electronic device 10 has been attached to power converter 12. Thus, monitor 54 may issue a command to power converter circuit 122 on path 76 to set power converter circuit 122 to its active mode.

Once power converter circuit 122 is activated, the output voltage from power converter circuit 122 may power electronic device 10 such that voltage Vbus can rise to its nominal value Vsec, as indicated by segment 102 in fig. 5. At a time (e.g., along line segment 104) after time tc, Vbus may be held at voltage Vsec by converter control circuitry 38.

Fig. 6 shows how Vbus may develop when monitor 54 opens switching circuit SW2 while electronic device 10 remains attached. At time tbg, power converter 12 is active and powers electronic device 10 by providing a voltage Vbus of Vsec. At time top, the monitor opens the switching circuit SW 2. Because electronic device 10 is connected to power converter 12, voltage Vbus drops. When a predetermined threshold voltage Vth1 is reached at time tcl, monitor 54 may conclude that electronic device 10 is still connected to power converter 12, and may close switching circuit SW 2. Voltage Vbus is preferably maintained above voltage Vmin (e.g., approximately 4.5 volts) to prevent electronic device 10 from erroneously inferring that electronic device 10 has been disconnected from power converter 12. Once switching circuit SW2 is closed, power is restored to output line 73 and voltage Vbus will rise, reaching nominal output voltage level Vsec at time tfn.

A diagram showing how power converter 12 and device 10 operate in system 8 of fig. 1 when a user attaches device 10 to power converter 12 and disconnects device 10 from power converter 12 is shown in fig. 7.

In active mode 106, power converter 12 operates normally as an AC-DC power converter and provides power from AC source 14 to attached electronic device 10. In a typical scenario, electronic device 10 contains a rechargeable battery that may be recharged when electronic device 10 is connected to power converter 12. During operation in mode 106, monitor 54 primarily keeps switching circuit SW2 closed to allow power to be delivered from line 64 to output line 73 and electronic device 10. At an appropriate time (e.g., once every few seconds, every few minutes, etc.), the monitor 54 temporarily opens the switching circuit SW2 to check whether the electronic device 10 is still attached. If voltage Vbus does not rise while switching circuit SW2 is open (e.g., if voltage Vbus falls to Vth1, as described in connection with fig. 6), monitor 54 may conclude that electronic device 10 is still attached to power converter 12. Thus, as indicated by line 108, operation of active mode 106 may continue uninterrupted.

However, if the voltage Vbus rises to the threshold Vth2 at the time the switching circuit SW2 is opened as described in connection with fig. 3, the monitor 54 can conclude that the device 10 has been disconnected. Monitor 54 may then place power converter circuit 122 and power converter 12 in standby mode 114, as indicated by line 110.

In standby mode 114, power converter circuit 122 is not active, and thus power converter circuit 122 cannot deliver power to power monitor 54. Instead, power is provided from the energy storage circuit 50. IN particular, the energy storage circuit 50 may provide a voltage Vstore (fig. 2) to the monitor 54 and to the input IN of the boost converter 52A. The energy storage circuit 50 may be used to power the monitoring circuit 54 and the voltage regulator 52 as long as the voltage level of the voltage Vstore is sufficient (i.e., above Vth 4). During this time, monitor 54 may periodically check the attachment status of electronic device 10. If voltage Vbus falls below Vth3 in one of these checks, as described in connection with fig. 5, monitor 54 may return power converter circuit 122 and power converter 12 to active mode 106, as indicated by line 112. If monitor 54 determines that voltage Vstore falls below Vth4, as described in connection with fig. 4, monitor 54 may temporarily activate power converter circuit 122 (active mode 118). In the active mode 118, the power converter circuit 122 is active and supplements the energy storage element 50 (e.g., by recharging the capacitor 80 on path 66). In operation in mode 118, device 10 remains off.

After the voltage Vstore recovers (line segment 92 of fig. 4), monitor 54 may return power converter circuit 122 and power converter 12 to standby mode 144 to conserve power, as indicated by line 120.

If desired, Vaux may be provided at different levels (e.g., a level greater than the minimum operating voltage of device 10 or other such load but not greater than Vsec). In the examples of fig. 4, 5, 6, and 7, the use of a Vaux value greater than Vsec helps facilitate detecting the attachment state of device 10 when switch SW2 is open. In situations where Vaux is not greater than Vsec, the presence of device 10 or other such load may be detected by determining that voltage Vbus has not dropped (e.g., Vbus has not dropped beyond a particular threshold voltage). Configurations in which Vaux is greater than Vsec are sometimes described herein as examples. However, this is merely illustrative.

As shown in fig. 8, the circuitry of system 8 may be incorporated into all or part of an electronic device, such as device 300. Device 300 may be a portable computer, a handheld computing device, a desktop computer, a consumer electronic device such as a television or stereo, a computer display, a game controller, or any other suitable electronic device. During normal operation, device 300 may be powered by the circuitry of power converter 12. This allows the circuitry of device 300 to be fully powered. The circuit components in device 300 are schematically illustrated in fig. 8 as device circuitry 210 and may include electronic components such as user interface components (e.g., a touch screen, touch pad, mouse, keys, buttons, circuitry for receiving wireless user commands such as infrared receiver circuitry for monitoring signals from a remote controller, radio frequency wireless communication circuitry for monitoring user signals, processing and storage circuitry, sensors, etc.).

The energy storage circuit 50 may be charged during normal operation. When power savings are desired, the circuit 122 may be set to a reduced power (standby) mode of operation. In standby mode, device circuitry 210 may wait for an action that indicates that device 300 should resume normal operation. For example, the device circuitry 210 may include infrared receiver circuitry or other user input circuitry that monitors for user input actions or other suitable events. When a user provides an infrared command or other action that is detected by the device circuitry 210, the resulting behavior of the device circuitry 210 may cause a change in the voltage on the line 72. Monitor 54 may sense this change in voltage and may issue a corresponding wake-up command to converter circuit 122 via path 76. Monitor 54 may also periodically wake up converter circuit 122 to supplement energy storage circuit 50, as described in connection with fig. 1.

If desired, circuit 210 may utilize other types of signaling mechanisms to notify monitor 54 that a user input or other monitored action has been detected. As an example, consider the arrangement of fig. 9. As shown in fig. 9, the electronic device 300 may have a power supply, such as the AC-DC power converter circuit 122, that charges an energy storage and power (voltage) regulator circuit 302. The circuit 302 may be, for example, a circuit that includes an energy storage circuit such as the energy storage circuit 50 of fig. 8, and optionally includes a voltage regulator or other circuit that helps regulate the output of the energy storage circuit when the circuit 210 is powered.

The processor 304 may include storage and processing circuitry, such as one or more microprocessors and other control circuitry (e.g., integrated circuits, etc.). Processor 304 may be used to control the operation of device 300 and circuitry 210.

During normal operation of the device 300 of fig. 9, the power supply 122 may power the circuit 302, and thus may charge the energy storage circuit 302. The circuit 210 and the processor 304 may be powered and may operate normally. When power savings are desired, the power supply 122 may be set (e.g., by the processor 304, monitor 210, or other control circuitry) to a standby state. In the standby state, the energy storage circuit may be used to power circuit 210 on path 306 and may be used to power monitor 54 on path 308.

Circuitry 210 may wait for user input such as an infrared remote control command or other suitable event indicating that device 300 should be brought out of standby mode. When such an event is detected, circuit 210 may notify monitor 54 of the occurrence of the event by sending a signal on path 310. Path 310 may be an analog or digital path having one or more associated lines for carrying communications between circuit 210 and monitor 54.

Once monitor 54 determines that it is appropriate to wake power supply 122 to process the user input command or other event, monitor 54 may issue an appropriate wake control command for power supply circuit 122 on path 76. The monitor 54 may also periodically wake the power supply 122 when it is desired to replenish the energy storage circuit in the energy storage and power regulator circuit 302 via path 210.

Fig. 10 shows how the device 300 may have multiple power supply circuits 122. In the example of fig. 10, the device 300 has a power supply circuit PS1 and a power supply circuit PS 2. Power supply PS1 may be a high power (primary) power supply providing tens or hundreds of watts of power, while power supply PS2 may be a low power (secondary) power supply providing less power (e.g., ten or less watts of power). In standby mode, each power supply consumes only a portion (e.g., 1-10%) of its available power capacity (as an example). These are merely illustrative examples. The primary power supply PS1 and the secondary power supply PS2 may have any suitable power supply capacity, if desired.

During normal operation, power supply PS1 may be in an active state and may provide power to circuitry 210, processor 304, and other components in device 300. To save power, power supply PS1 may be set to a low power standby state when full power is not required. Likewise, when no active operation is required, the power supply PS2 is also set to a standby state in order to save power. In the standby state, the energy storage and voltage regulator circuit 302 may supply power to the circuit 210, as described in connection with fig. 9. From time to time, the energy storage circuitry in circuit 302 may need to be replenished. As described in connection with the circuit of fig. 1, the monitor 54 may monitor the state of the energy storage circuit. When replenishment is desired, monitor 54 may issue a replenishment control signal on path 314 to power supply PS 2. In response, the power supply PS2 may be awakened from its standby state. Because power supply PS2 uses less energy than power supply PS1, and because not the entire device 300 needs to be powered during supplemental operations with respect to power supply PS2, supplementing the energy storage circuit with power supply PS2 while power supply PS1 remains in the standby state can help conserve power.

If circuit 210 detects a user input or other action that indicates that device 300 should enter its active state, circuit 210 may instruct monitor 54 to wake up power supply PS1 via path 316. Monitor 54 may also wake up power supply PS 2. The circuit 210 may also use the processor 304 to issue wake-up commands and other control commands, if desired. The processor 304 may wake up the power supply PS1, for example, each time a user input is received with the circuit 210, while the monitor 54 may be used to wake up the power supply PS2 (as an example).

An illustrative configuration of a power adapter 12, such as the power adapter 12 of FIG. 1, is shown in FIG. 11. As shown in fig. 11, the power adapter may have a housing, such as housing 318, in which circuitry, such as circuitry 12 of fig. 1, may be mounted. The conductive pins 320 may be used to connect the power adapter to AC line power. Cable 322 may be used to transmit the output signal from adapter 12 to connector 324. The connector 324 may be used to connect the power adapter to the electronic device 10. Connector 324 may be, for example, a 30 pin connector of the type sometimes used to couple music players and telephone devices to computers and power supplies. In general, the connector 324 may have any suitable number of contacts. The use of a 30 pin arrangement is merely illustrative.

FIG. 12 shows another illustrative power adapter arrangement. In the arrangement of fig. 12, the power adapter circuit of fig. 1 is mounted in a housing 326. The connector 328 in the example of FIG. 12 may be, for example, from Apple Inc. of Cupertino, CalifMagnetic connector of connector. This type of connector uses magnetic attraction to help secure the connector 328 to the mating device. For example, there may be a magnet in the portion 330 of the connector 328. Plug type connectors may also be used in the power adapter 12 if desired.

As shown in fig. 13, energy storage circuit 50 may form part of AC-DC power converter circuit 122. For example, converter circuit 122 may be a type of converter circuit having a capacitor across its positive and ground output lines (e.g., for filtering). In this type of arrangement, energy used to power the monitor 54 and to power circuitry such as the circuit 210 (the device 10 in the example of fig. 13) can be stored in such a filter capacitor without the need for an additional energy storage device. In general, the energy storage circuit 50 may be formed from any number of suitable components (capacitors, batteries, etc.) and these components may form a stand-alone circuit or, if desired, may be combined into other circuits in the system 8. Examples such as the illustrative configurations of fig. 1 and 13 are illustrative only.

According to one embodiment, there is provided an Alternating Current (AC) to Direct Current (DC) power converter to which an electronic device may be connected when it is desired to power the electronic device with the power converter, the power converter comprising: a power converter circuit that generates a DC voltage from an AC voltage; an output line to which the electronic device can be connected; a switching circuit coupled between the power converter circuit and the output line to periodically disconnect the power converter circuit from the output line; and a determination circuit that determines whether the electronic device is attached to the output line by monitoring a voltage level on the output line when the power converter circuit is disconnected from the output line by the switching circuit.

According to another embodiment, the power converter comprises a control circuit, and the determination circuit comprises a monitor that instructs the control circuit to set the power converter circuit in a standby mode upon determining that the electronic device has been disconnected from the output line.

According to another embodiment, the power converter further comprises an energy storage element storing energy for powering the monitor when the power converter circuit is in the standby mode, wherein the monitor is configured to instruct the control circuit to temporarily set the power converter circuit in the active mode instead of the standby mode when the monitor determines that the energy storage element is to be replenished.

According to another embodiment, the monitor is configured to instruct the control circuit to set the power converter circuit to the active mode upon determining that the electronic device has been attached to the output line when operating the power converter circuit in the standby mode.

According to another embodiment, the energy storage element comprises a capacitor.

According to another embodiment, the power converter further comprises a voltage regulator that receives the energy storage element voltage from the energy storage element and provides a corresponding altered version of the energy storage element voltage on a voltage regulator output when the voltage regulator output is not loaded by the electronic device.

According to another embodiment, the power converter further includes a path electrically coupling the voltage regulator output to the output line, and the altered version of the energy storage element voltage is greater than the DC voltage generated by the power converter circuit

According to another embodiment, the power converter further comprises a current limiting circuit inserted into a path electrically coupling the voltage regulator output to the output line.

According to another embodiment, the voltage regulator includes a DC-DC switched mode power converter that generates an altered version of the energy storage element voltage, and the altered version of the energy storage element voltage is greater than the energy storage element voltage.

According to another embodiment, the defined power converter further comprises a path electrically coupling the voltage regulator output to the output line, and the altered version of the energy storage element voltage is no greater than the DC voltage generated by the power converter circuit.

According to another embodiment, the monitor is configured to instruct the control circuit to set the power converter circuit to the active mode upon determining that the electronic device is attached to the output line when operating the power converter circuit in the standby mode.

According to one embodiment, there is provided an Alternating Current (AC) to Direct Current (DC) power converter to which an electronic device may be connected when it is desired to power the electronic device with the power converter, the power converter comprising: a switched mode power converter circuit that generates a DC voltage from an AC voltage and is operable in an active mode in which the DC voltage is generated and a standby mode in which the DC voltage is not generated; an output line to which the electronic device may be connected to receive an output line voltage equal to the DC voltage generated by the switched mode power converter circuit to power the electronic device; a switching circuit coupled between the switched mode power converter circuit and the output line; an energy storage element generating an energy storage element voltage; a voltage regulator receiving the energy storage element voltage and having a voltage regulator output coupled to the output line; and a monitor monitoring the energy storage element voltage and the output line voltage and controlling the switching circuit and the switched mode power converter circuit.

According to another embodiment, the monitor is configured to: temporarily open the switching circuit when the power converter circuit is in an active mode to isolate the output line from the switching mode power converter circuit; monitoring whether the output line voltage rises while the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is disconnected from the power converter; and monitoring whether the output line voltage drops when the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is attached to the power converter.

According to another embodiment, the voltage regulator includes a boost converter that provides a voltage regulator output voltage at a voltage regulator output, the voltage regulator output voltage having a voltage level greater than a DC voltage generated by the switched mode power converter circuit when the electronic device is disconnected from the output line and not loaded by the output line.

According to another embodiment, the voltage regulator further comprises a current limiting circuit that ensures output line voltage droop when the electronic device is attached to an output line power converter and the switched mode power converter circuit is isolated from the output line by opening the switching circuit.

According to another embodiment, the monitor is configured to: temporarily opening the switching circuit when the switching mode power converter circuit is in an active mode to isolate the output line from the switching mode power converter circuit; monitoring whether the output line voltage does not drop above a given threshold while the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is disconnected from the power converter; and monitoring whether the output line voltage drops more than a given threshold when the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is attached to the power converter.

According to one embodiment, a method of operating an Alternating Current (AC) to Direct Current (DC) power converter having output lines to which electronic devices may be connected when it is desired to power the electronic devices with the power converter is provided, wherein the power converter has a switched mode power converter circuit operable in an active mode in which a DC voltage is generated and a standby mode in which no DC voltage is generated. The method comprises the following steps: temporarily isolating the switched mode power converter circuit from the output line; monitoring a voltage level on the output line; and controlling whether the switched mode power converter circuit operates in an active mode or a standby mode in response to the monitored voltage level.

According to another embodiment, wherein monitoring the voltage level includes determining whether the monitored voltage level of the output line rises when temporarily isolating the switched mode power converter circuit from the output line, which indicates that the electronic device is disconnected from the output line. The method further comprises the following steps: setting the switched mode power converter circuit to a standby mode upon determining that the electronic device has been disconnected from the output line.

According to another embodiment, wherein monitoring the voltage level comprises determining whether the monitored voltage level of the output line drops when temporarily isolating the switched mode power converter circuit from the output line, indicating that the electronic device has been attached to the output line. The method further comprises the following steps: setting the switched mode power converter circuit to an active mode upon determining that the electronic device has been attached to the output line.

According to another embodiment, wherein monitoring the voltage level comprises monitoring the voltage level with a monitor, the method further comprising: when the switched-mode power converter circuit is in a standby mode, the monitor is powered with a capacitor.

According to another embodiment, the method further comprises: temporarily setting the switched mode power converter to an active mode when the electronic device is disconnected from the output line, so as to temporarily generate a DC output voltage to charge a capacitor.

According to an embodiment, there is provided a circuit system comprising: a first power supply circuit; a second power supply circuit; an energy storage circuit; and a circuit powered by an energy storage device when the first power supply circuit and the second power supply circuit are set to a standby state for power saving.

According to another embodiment, the circuitry powered by the energy storage circuit includes circuitry to monitor user actions.

According to another embodiment, the circuitry powered by the energy storage circuit comprises an infrared receiver, and wherein the circuitry comprises at least a portion of a television.

According to another embodiment, the circuitry further includes a monitor circuit that receives a signal from the circuitry powered by the energy storage circuit when the circuitry powered by the energy storage circuit detects an action, and wakes up the first power supply circuit to power the circuitry when a signal from the circuitry powered by the energy storage circuit is received.

According to another embodiment, the circuitry further includes a monitor circuit configured to determine when the energy storage circuit is depleted and configured to wake the second power supply circuit to replenish the energy storage circuit without waking the first power supply.

According to another embodiment, the monitor circuit receives a signal from a circuit powered by the energy storage circuit when the circuit powered by the energy storage circuit detects an action indicating that the circuitry should operate in a normal operating mode, and the monitor circuit is configured to wake up the first power supply circuit to power the circuitry in response to the signal from the circuit powered by the energy storage circuit.

According to another embodiment, the energy storage circuit includes a capacitor.

According to another embodiment, the energy storage circuit includes a capacitor, and the capacitor and the second power supply circuit form part of an Alternating Current (AC) to Direct Current (DC) power converter circuit.

According to one embodiment, there is provided an electronic device comprising: a first switched mode Alternating Current (AC) to Direct Current (DC) power supply circuit operating in an active mode and a standby mode; a second AC-DC power supply circuit operating in an active mode and a standby mode; an energy storage circuit at least occasionally charged by the second AC-DC power supply circuit when the first switched mode AC-DC power supply circuit is in its standby mode; and at least one circuit for powering the energy storage circuit when the first switched-mode AC-DC power supply circuit and the second switched-mode AC-DC power supply circuit are operating in their standby modes.

According to another embodiment, the electronic device further comprises a monitor circuit in communication with the at least one circuit and configured to change the first switched-mode AC-DC power supply circuit from its standby mode to its active mode in response to a signal received from the at least one circuit.

The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Claims (31)

1. An Alternating Current (AC) to Direct Current (DC) power converter to which an electronic device may be connected when it is desired to power the electronic device with the power converter, the power converter comprising:

a power converter circuit that generates a DC voltage from an AC voltage;

an output line to which the electronic device can be connected;

a switching circuit coupled between the power converter circuit and the output line to periodically disconnect the power converter circuit from the output line;

a determination circuit that determines whether the electronic device is attached to the output line by monitoring a voltage level on the output line when the power converter circuit is disconnected from the output line by the switching circuit; and

a voltage regulator electrically coupled to the output line and configured to provide a regulated voltage to the output line when the power converter circuit is disconnected from the output line by the switching circuit.

2. The power converter of claim 1, wherein the power converter circuit comprises a control circuit, and wherein the determination circuit comprises a monitor that instructs the control circuit to place the power converter circuit in a standby mode upon determining that the electronic device has been disconnected from the output line.

3. The power converter of claim 2, further comprising an energy storage element that stores energy used to power the monitor when the power converter circuit is in the standby mode, wherein the monitor is configured to instruct the control circuit to temporarily place the power converter circuit in the active mode instead of the standby mode when the monitor determines that the energy storage element is to be replenished.

4. The power converter of claim 3, wherein the monitor is configured to instruct the control circuit to place the power converter circuit in an active mode upon determining that the electronic device has been attached to the output line when operating the power converter circuit in a standby mode.

5. The power converter of claim 3, wherein the energy storage element comprises a capacitor.

6. The power converter of claim 3, wherein the voltage regulator receives an energy storage element voltage from the energy storage element, and wherein the regulated voltage is based in part on the energy storage element voltage.

7. The power converter of claim 6, further comprising a path electrically coupling the voltage regulator to the output line, and wherein the regulated voltage is greater than a DC voltage generated by the power converter circuit.

8. The power converter of claim 7, further comprising a current limiting circuit inserted into a path that electrically couples the voltage regulator to the output line.

9. The power converter of claim 7, wherein the voltage regulator comprises a DC-DC switching mode power converter that generates the regulated voltage, and wherein the regulated voltage is greater than the energy storage element voltage.

10. The power converter of claim 6, further comprising a path electrically coupling the voltage regulator to the output line, and wherein the regulated voltage is no greater than a DC voltage generated by the power converter circuit.

11. The power converter of claim 2, wherein the monitor is configured to instruct the control circuit to place the power converter circuit in an active mode upon determining that the electronic device is attached to the output line when operating the power converter circuit in a standby mode.

12. An Alternating Current (AC) to Direct Current (DC) power converter to which an electronic device may be connected when it is desired to power the electronic device with the power converter, the power converter comprising:

a switched mode power converter circuit that generates a DC voltage from an AC voltage and is operable in an active mode in which the DC voltage is generated and a standby mode in which the DC voltage is not generated;

an output line to which the electronic device may be connected to receive an output line voltage equal to the DC voltage generated by the switched mode power converter circuit to power the electronic device;

a switching circuit coupled between the switched mode power converter circuit and the output line;

an energy storage element generating an energy storage element voltage;

a voltage regulator receiving the energy storage element voltage and having a voltage regulator output coupled to the output line; and

a monitor that monitors the energy storage element voltage and the output line voltage and controls the switching circuit and a switched mode power converter circuit.

13. The power converter of claim 12, wherein the monitor is configured to:

temporarily open the switching circuit when the power converter circuit is in an active mode to isolate the output line from the switching mode power converter circuit;

monitoring whether the output line voltage rises while the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is disconnected from the power converter; and

monitoring whether the output line voltage drops while the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is attached to the power converter.

14. The power converter of claim 13, wherein the voltage regulator includes a boost converter that provides a voltage regulator output voltage at a voltage regulator output, the voltage regulator output voltage having a voltage level greater than a DC voltage generated by the switched mode power converter circuit when the electronic device is disconnected from the output line and not loaded by the output line.

15. The power converter of claim 14, wherein the voltage regulator further comprises a current limiting circuit that ensures output line voltage droop when the electronic device is attached to an output line and the switched mode power converter circuit is isolated from the output line by opening the switching circuit.

16. The power converter of claim 12, wherein the monitor is configured to:

temporarily opening the switching circuit when the switching mode power converter circuit is in an active mode to isolate the output line from the switching mode power converter circuit;

monitoring whether the output line voltage does not drop above a given threshold while the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is disconnected from the power converter; and

monitoring whether the output line voltage drops more than a given threshold when the output line is isolated from the switched mode power converter circuit, which indicates that the electronic device is attached to the power converter.

17. A method of operating an Alternating Current (AC) to Direct Current (DC) power converter, wherein the power converter has an output line to which an electronic device may be connected when it is desired to power the electronic device with the power converter, wherein the power converter has a switched mode power converter circuit operable in an active mode in which a DC voltage is generated and a standby mode in which no DC voltage is generated, wherein a switch is interposed between an energy storage element and the output line, the method comprising:

temporarily isolating the switched mode power converter circuit from the output line by opening the switch interposed between the energy storage element and the output line;

monitoring a voltage level on the output line; and

controlling whether the switched-mode power converter circuit operates in an active mode or a standby mode in response to the monitored voltage level.

18. The method of claim 17, wherein monitoring the voltage level comprises determining whether the monitored voltage level of the output line rises when temporarily isolating the switched mode power converter circuit from the output line, indicating that the electronic device is disconnected from the output line, the method further comprising:

setting the switched mode power converter circuit to a standby mode upon determining that the electronic device has been disconnected from the output line.

19. The method of claim 18, wherein monitoring the voltage level comprises determining whether the monitored voltage level of the output line has dropped when temporarily isolating the switched mode power converter circuit from the output line, indicating that the electronic device has been attached to the output line, the method further comprising:

setting the switched mode power converter circuit to an active mode upon determining that the electronic device has been attached to the output line.

20. The method of claim 19, wherein monitoring the voltage level comprises monitoring the voltage level with a monitor, and the energy storage element comprises a capacitor, the method further comprising:

powering the monitor with the capacitor when the switched-mode power converter circuit is in a standby mode.

21. The method of claim 20, further comprising:

temporarily setting the switched-mode power converter circuit to an active mode when the electronic device is disconnected from the output line, so as to temporarily generate a DC output voltage to charge a capacitor.

22. A circuit system, comprising:

a first power supply circuit;

a second power supply circuit;

an energy storage circuit; and

circuitry powered by an energy storage device when the first power supply circuit and the second power supply circuit are set to a standby state for power conservation.

23. The circuitry defined in claim 22 wherein the circuitry that is powered by the energy storage circuitry comprises circuitry that monitors user activity.

24. The circuitry defined in claim 22 wherein the circuitry that is powered by the energy storage circuitry comprises an infrared receiver and wherein the circuitry comprises at least part of a television.

25. The circuitry defined in claim 22 further comprising a monitor circuit that receives a signal from the circuitry that is powered by the energy storage circuit when the circuitry that is powered by the energy storage circuit detects an action and that wakes up the first power circuit to power the circuitry when a signal is received from the circuitry that is powered by the energy storage circuit.

26. The circuitry defined in claim 22 further comprising a monitor circuit that is configured to determine when the energy storage circuit is depleted and to wake the second power supply circuit to replenish the energy storage circuit without waking the first power supply circuit.

27. The circuitry defined in claim 26 wherein the monitor circuit receives a signal from the circuitry that is powered by the energy storage circuit when the circuitry that is powered by the energy storage circuit detects an action that indicates that the circuitry should operate in a normal operating mode, and wherein the monitor circuit is configured to wake up the first power supply circuit to power the circuitry in response to the signal from the circuitry that is powered by the energy storage circuit.

28. The circuitry defined in claim 22 wherein the energy storage circuitry comprises a capacitor.

29. The circuitry defined in claim 22 wherein the energy storage circuitry comprises a capacitor and wherein the capacitor and the second power supply circuitry form part of an Alternating Current (AC) to Direct Current (DC) power converter circuit.

30. An electronic device, comprising:

a first switched mode Alternating Current (AC) to Direct Current (DC) power supply circuit operating in an active mode and a standby mode;

a second switched-mode AC-DC power supply circuit operating in an active mode and a standby mode;

an energy storage circuit at least occasionally charged by the second switched mode AC-DC power supply circuit when the first switched mode AC-DC power supply circuit is in its standby mode; and

at least one circuit that uses the energy storage circuit to supply power when the first switched-mode AC-DC power supply circuit and the second switched-mode AC-DC power supply circuit are operating in their standby modes.

31. The electronic device defined in claim 30 further comprising a monitor circuit in communication with the at least one circuit and configured to change the first switched-mode AC-DC power supply circuit from its standby mode to its active mode in response to a signal received from the at least one circuit.