TWI882615B - Current mode boost DC to DC converter, power management chip, display and information processing device - Google Patents

Abstract

A current mode boost type DC to DC converter is used to convert an input voltage into an output voltage to provide a driving current for a load according to the control of a PWM signal, wherein the PWM signal is generated according to a potential comparison operation of a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and its characteristics are The characteristic is that the ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current.

Description

Current mode boost DC to DC converter, power management chip, display and information processing device

The present invention relates to a DC to DC converter, and more particularly to a DC to DC converter that can respond to changes in load current.

Please refer to FIG1, which shows a circuit diagram of a conventional current mode boost DC to DC converter. As shown in FIG1, the current mode boost DC to DC converter mainly includes a power conversion unit and a control module to convert an input voltage VIN into an output voltage VOUT, wherein the power conversion unit includes an inductor 16, an NMOS transistor 17, a PMOS transistor 18a and an output capacitor 19; the control module includes a ramp signal generating unit, an error signal generating unit, a PWM signal generating unit, a voltage sensing unit and an inductive sensing unit.

The ramp signal generating unit includes a capacitor 11b, a switch 11c and a resistor 11d, and generates a periodic ramp signal VRAMP according to the current of a current source 11a, a sense current ISENSE and the periodic conduction and disconnection of the switch 11c. The amplitude of the periodic ramp signal VRAMP is proportional to the current source 11a, and its DC level can be modulated by the sense current ISENSE.

The error signal generating unit includes a transconductance amplifier 12a, a resistor 12b and a capacitor 12c, and is used to generate an average value signal VEA of the potential difference between a feedback voltage VFB and a reference voltage VREF.

The PWM signal generating unit includes a comparator 13, a latch 14 and a PWM control driver 15, and is used to generate a pulse width modulation signal PWM according to the comparison result between the periodic ramp signal VRAMP and the average value signal VEA.

The voltage sensing unit has a voltage dividing circuit composed of a resistor 19a and a resistor 19b to divide the output voltage VOUT to generate a feedback voltage VFB.

The current sensing unit has a PMOS transistor 18b, an amplifier 20 and a PMOS transistor 21, wherein the PMOS transistor 18b, the amplifier 20 and the PMOS transistor 21 are used to mirror the channel current of the PMOS transistor 18a to generate the sensing current ISENSE.

Accordingly, the duty cycle of the pulse width modulation signal PWM of the current mode boost DC-DC converter can quickly respond to changes in the load current.

However, the current mode boost DC-DC converter cannot quickly respond to changes in the input power supply VIN and cannot meet the requirements of specific applications. For example, in the power drive management chip of AMOLED, there is a test requirement: the input power supply VIN will be disturbed at intervals, and will jump 500mV up or down within 10uS, and the 500mV jump will last for at least 500uS; under this interference condition, the output voltage ripple of the boost DC-DC converter should be less than 20mV when the load is less than 200Ma, and less than 60mV when the load is less than 1A.

To solve the above problems, a novel current mode boost DC-DC converter is urgently needed in the art.

The main purpose of the present invention is to provide a current mode boost type DC to DC converter, which can adaptively adjust the duty cycle of a PWM signal by making the offset level of a ramp signal a function of the input voltage and the drive current, so as to quickly respond to the changes of the input voltage and the load current to minimize the ripple of the output voltage.

To achieve the above purpose, a current mode boost type DC to DC converter is proposed, which is used to convert an input voltage into an output voltage under the control of a PWM signal to provide a driving current for a load, wherein the PWM signal is generated by a potential comparison operation of a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, and the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and its characteristics are: The ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current.

In one embodiment, the current mode boost DC-to-DC converter has an input voltage processing unit and a first transconductance amplifier, wherein the input voltage processing unit is used to generate a first control voltage VC1 according to the input voltage, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is the average potential of the input voltage, and VINDIFF is the potential change of the input voltage; and the first transconductance amplifier is used to generate the first slot current according to the first control voltage VC1.

In one embodiment, the current mode boost DC-to-DC converter has a composite signal processing unit and a second transconductance amplifier, wherein the composite signal processing unit is used to generate a second control voltage according to the product of the potential change of the input voltage and the average current of the driving current; and the second transconductance amplifier is used to generate the second slot current according to the second control voltage.

To achieve the above-mentioned purpose, the present invention further proposes a power management chip, which has a current mode boost type DC to DC converter to convert an input voltage into an output voltage according to the control of a PWM signal to provide a driving current for a load, wherein the PWM signal is generated according to a potential comparison operation of a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and its characteristics are: The ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current.

In one embodiment, the current mode boost DC-to-DC converter has an input voltage processing unit and a first transconductance amplifier, wherein the input voltage processing unit is used to generate a first control voltage VC1 according to the input voltage, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is the average potential of the input voltage, and VINDIFF is the potential change of the input voltage; and the first transconductance amplifier is used to generate the first slot current according to the first control voltage VC1.

In one embodiment, the current mode boost DC-to-DC converter has a composite signal processing unit and a second transconductance amplifier, wherein the composite signal processing unit is used to generate a second control voltage according to the product of the potential change of the input voltage and the average current of the driving current; and the second transconductance amplifier is used to generate the second slot current according to the second control voltage.

To achieve the above-mentioned purpose, the present invention further proposes a display having a power management chip, the power management chip having a current mode boost type DC to DC converter to convert an input voltage into an output voltage under the control of a PWM signal to provide a driving current for a load, wherein the PWM signal is generated according to a potential comparison operation of a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and its characteristics are: The ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current.

In one embodiment, the current mode boost DC-to-DC converter has an input voltage processing unit and a first transconductance amplifier, wherein the input voltage processing unit is used to generate a first control voltage VC1 according to the input voltage, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is the average potential of the input voltage, and VINDIFF is the potential change of the input voltage; and the first transconductance amplifier is used to generate the first slot current according to the first control voltage VC1.

In one embodiment, the current mode boost DC-to-DC converter has a composite signal processing unit and a second transconductance amplifier, wherein the composite signal processing unit is used to generate a second control voltage according to the product of the potential change of the input voltage and the average current of the driving current; and the second transconductance amplifier is used to generate the second slot current according to the second control voltage.

In a possible embodiment, the display may be a liquid crystal display, a sub-millimeter light emitting diode display, a micro-light emitting diode display, a quantum dot light emitting diode display or an organic light emitting diode display.

To achieve the above object, the present invention further proposes an information processing device having a central processing unit and the display as described above, wherein the central processing unit is used to communicate with the display.

In a possible embodiment, the information processing device may be a portable computer, a car computer, a smart watch, a smart bracelet or a smart phone.

In order to enable the Review Committee to further understand the structure, features, purpose, and advantages of the present invention, the following are attached with drawings and detailed descriptions of preferred specific embodiments.

Please refer to FIG. 2, which shows a block diagram of an embodiment of the current mode boost DC-DC converter of the present invention. As shown in FIG. 2, a current mode boost DC-DC converter 100 includes a power conversion unit and a control module to convert an input voltage VIN into an output voltage VOUT, wherein the power conversion unit includes an inductor 116, an NMOS transistor 117, a PMOS transistor 118a and an output capacitor 119; the control module includes a ramp signal generating unit, an error signal generating unit, a PWM signal generating unit, a voltage sensing unit, an inductive current sensing unit and an average inductive current sensing unit 120.

The ramp signal generating unit includes a capacitor 111b, a switch 111c and a resistor 111d, and generates a periodic ramp signal VRAMP according to the current of a current source 111a, an offset control current ISENSE and the periodic conduction and disconnection of the switch 111c. The amplitude of the periodic ramp signal VRAMP is proportional to the current source 111a, and its DC level can be modulated by the offset control current ISENSE.

The error signal generating unit includes a transconductance amplifier 112a, a resistor 112b and a capacitor 112c, and is used to generate an error average signal VEA. The error average signal VEA is generated by an average value of a difference between a feedback voltage VFB and a reference voltage VREF.

The PWM signal generating unit includes a comparator 113, a latch 114 and a PWM control driver 115, and is used to generate a pulse width modulation signal PWM according to the comparison result between the periodic ramp signal VRAMP and the average value signal VEA.

The voltage sensing unit has a voltage dividing circuit composed of a resistor 119a and a resistor 119b to divide the output voltage VOUT to generate a feedback voltage VFB.

The current sensing unit has a PMOS transistor 118b, an amplifier 118c and a PMOS transistor 118d, wherein the PMOS transistor 118b, the amplifier 118c and the PMOS transistor 118d are used to mirror the channel current of the PMOS transistor 118a to generate a load mirror current ILM.

The average current sensing unit 120 is used to sense an average current of the load current to generate a control voltage VCTL.

In addition, the offset control current ISENSE is generated by an input voltage processing unit 121, a complex signal processing unit 122, a first transconductance amplifier 123 and a second transconductance amplifier 124.

The input voltage processing unit 121 is used to generate a first control voltage VC1 according to the input voltage VIN, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is an average potential of the input voltage VIN, and VINDIFF is a potential change of the input voltage VIN; and the first transconductance amplifier 123 is used to generate the first slot current ISINK1 according to the first control voltage VC1.

The complex signal processing unit 122 is used to generate a second control voltage VC2 according to the product of the potential change of the input voltage VIN and an average current of the load current; and the second transconductance amplifier 124 is used to generate a second sink current ISINK2 according to the second control voltage VC2.

From the above, it can be known that the offset control current ISENSE = ILM-(ISINK1+ISINK2). Accordingly, the present invention can change the duty cycle of the pulse width modulation signal PWM to minimize the ripple of VOUT when VIN and/or VCTL change.

According to the above description, the present invention further proposes a power management chip. Please refer to FIG. 3, which shows a block diagram of an embodiment of the power management chip of the present invention. As shown in FIG. 3, a power management chip 200 has a current mode boost type DC to DC converter 210 to provide a stable DC supply voltage for an electronic device, and the current mode boost type DC to DC converter 210 is implemented by the current mode boost type DC to DC converter 100.

According to the above description, the present invention further proposes a display. Please refer to FIG. 4, which shows a block diagram of an embodiment of the display of the present invention. As shown in FIG. 4, a display 300 has a power management chip 310, a control circuit 320 and a display panel 330, wherein the power management chip 310 is implemented by the power management chip 200 to provide a stable DC supply voltage for the control circuit 320 to drive the display panel 330.

In addition, the display 300 may be a liquid crystal display, a sub-millimeter light emitting diode display, a micro light emitting diode display, a quantum dot light emitting diode display or an organic light emitting diode display.

In addition, according to the above description, the present invention further proposes an information processing device. Please refer to FIG. 5, which shows a block diagram of an embodiment of the information processing device of the present invention. As shown in FIG. 5, an information processing device 400 has a central processing unit 410 and a display 420, wherein the display 420 is implemented by the display 300 and the central processing unit 410 is used to communicate with the display 420.

In addition, the information processing device 400 may be a portable computer, a car computer, a smart watch, a smart bracelet, or a smart phone.

According to the above design, the present invention has the following advantages: The current mode boost DC-DC converter of the present invention can adaptively adjust the duty cycle of a PWM signal by making the offset level of a ramp signal a function of the input voltage and the drive current, thereby quickly responding to the changes of the input voltage and the load current to minimize the ripple of the output voltage.

The invention disclosed in this case is a preferred embodiment. Any partial changes or modifications that are derived from the technical concept of this case and are easily inferred by people familiar with the art do not deviate from the scope of the patent rights of this case.

In summary, this case shows that it is very different from the known technology in terms of purpose, means and effect, and it is the first invention that is practical and indeed meets the patent requirements for invention. We sincerely request the review committee to examine this carefully and grant a patent as soon as possible to benefit the society. This is our utmost prayer.

11a: Current source 11b: Capacitor 11c: Switch 11d: Resistor 12a: Transconductance amplifier 12b: Resistor 12c: Capacitor 13: Comparator 14: Latch 15: PWM control driver 16: Inductor 17: NMOS transistor 18a: PMOS transistor 18b: PMOS transistor 19: Output capacitor 19a: Resistor 19b: Resistor 20: Amplifier 21: PMOS transistor 100: Current mode boost DC-DC converter 111a: Current source 111b: Capacitor 111c: switch 111d: resistor 112a: transconductance amplifier 112b: resistor 112c: capacitor 113: comparator 114: latch 115: PWM control driver 116: inductor 117: NMOS transistor 118a: PMOS transistor 118b: PMOS transistor 118c: amplifier 118d: PMOS transistor 119: output capacitor 119a: resistor 119b: resistor 120: average current sensing unit 121: input voltage processing unit 122: complex signal processing unit 123: First transconductance amplifier 124: Second transconductance amplifier 200: Power management chip 210: Current mode boost DC to DC converter 300: Display 310: Power management chip 320: Control circuit 330: Display panel 400: Information processing device 410: Central processing unit 420: Display

FIG. 1 shows a circuit diagram of a conventional current-mode boost DC-DC converter; FIG. 2 shows a block diagram of an embodiment of the current-mode boost DC-DC converter of the present invention; FIG. 3 shows a block diagram of an embodiment of the power management chip of the present invention; FIG. 4 shows a block diagram of an embodiment of the display of the present invention; and FIG. 5 shows a block diagram of an embodiment of the information processing device of the present invention.

100: Current mode boost DC to DC converter

111a: Current source

111b: Capacitor

111c: Switch

111d:Resistance

112a: transduction amplifier

112b:Resistance

112c: Capacitor

113: Comparator

114: latch lock

115:PWM controlled driver

116: Inductor

117:NMOS transistor

118a:PMOS transistor

118b:PMOS transistor

118c:Amplifier

118d:PMOS transistor

119: Output capacitor

119a:Resistance

119b:Resistance

120: Average current measurement unit

121: Input voltage processing unit

122: Composite signal processing unit

123: First transduction amplifier

124: Second transduction amplifier

Claims (9)

A current mode boost type DC to DC converter is used to convert an input voltage into an output voltage under the control of a PWM signal to provide a driving current for a load, wherein the PWM signal is generated by a potential comparison operation of a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and is characterized in that: The ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current; and The current mode boost DC-DC converter has an input voltage processing unit and a first transconductance amplifier, wherein the input voltage processing unit is used to generate a first control voltage VC1 according to the input voltage, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is the average potential of the input voltage, and VINDIFF is the potential variation of the input voltage; and the first transconductance amplifier is used to generate the first tank current according to the first control voltage VC1. A current-mode boost DC-to-DC converter as described in claim 1, which has a composite signal processing unit and a second transconductance amplifier, wherein the composite signal processing unit is used to generate a second control voltage according to the product of the potential change of the input voltage and the average current of the driving current; and the second transconductance amplifier is used to generate the second slot current according to the second control voltage. A power management chip having a current mode boost type DC to DC converter to convert an input voltage into an output voltage under the control of a PWM signal to provide a driving current for a load, wherein the PWM signal is generated by a potential comparison operation between a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and is characterized in that: The ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current; and The current mode boost type DC to DC converter has an input voltage processing unit and a first transconductance amplifier, wherein the input voltage processing unit is used to generate a first control voltage VC1 according to the input voltage, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is the average potential of the input voltage, and VINDIFF is the potential variation of the input voltage; and the first transconductance amplifier is used to generate the first tank current according to the first control voltage VC1. A power management chip as described in claim 3, wherein the current mode boost DC-to-DC converter has a composite signal processing unit and a second transconductance amplifier, wherein the composite signal processing unit is used to generate a second control voltage according to the product of the potential change of the input voltage and the average current of the driving current; and the second transconductance amplifier is used to generate the second slot current according to the second control voltage. A display having a power management chip having a current mode boost type DC to DC converter to convert an input voltage into an output voltage under the control of a PWM signal to provide a driving current for a load, wherein the PWM signal is generated by a potential comparison operation between a ramp signal and an error signal, the ramp signal has an amplitude and a DC offset, the error signal is generated according to the average value of the difference between the output voltage and a reference voltage, and is characterized in that: The ramp signal has a fixed amplitude, a preset offset level and a variable offset level, and the variable offset level is inversely proportional to the sum of a first slot current and a second slot current, wherein the first slot current is determined by an average potential of the input voltage and a potential change of the input voltage in a predetermined period, and the second slot current is determined by the product of the potential change and an average current of the driving current; and The current mode boost type DC to DC converter has an input voltage processing unit and a first transconductance amplifier, wherein the input voltage processing unit is used to generate a first control voltage VC1 according to the input voltage, which is represented by the following formula: VC1=(A-VINAVG)+VINDIFF, wherein A is an initial potential, VINAVG is the average potential of the input voltage, and VINDIFF is the potential variation of the input voltage; and the first transconductance amplifier is used to generate the first tank current according to the first control voltage VC1. A display as described in claim 5, wherein the current mode boost DC to DC converter has a composite signal processing unit and a second transconductance amplifier, wherein the composite signal processing unit is used to generate a second control voltage according to the product of the potential change of the input voltage and the average current of the driving current; and the second transconductance amplifier is used to generate the second slot current according to the second control voltage. The display as described in claim 5 is selected from the group consisting of a liquid crystal display, a sub-millimeter light-emitting diode display, a micro-light-emitting diode display, a quantum dot light-emitting diode display and an organic light-emitting diode display. An information processing device having a central processing unit and a display as described in any one of claims 5 to 7, wherein the central processing unit is used to communicate with the display. The information processing device as described in claim 8 is selected from the group consisting of a portable computer, a car computer, a smart watch, a smart bracelet and a smart phone.

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