TWI864636B - Charger circuit with thermal regulation - Google Patents

Abstract

A charger circuit comprises a constant current charging circuit and a thermal regulation circuit. The constant current charging circuit is configured for generating a charging current, including a charger input terminal for receiving an input voltage, a charge current setting terminal, a charger output terminal for outputting the charging current, a current mirror including a reference current path between the charger input terminal and charge current setting terminal and an output current path between the charger input terminal and charger output terminal, and a feedback amplifier having a positive terminal, a negative terminal for receiving a feedback reference voltage, and a feedback output terminal coupled to the current mirror. The thermal regulation circuit is configured for generating and modulating a thermal regulation voltage with temperature, and outputting the thermal regulation voltage across the positive terminal of the feedback amplifier and the charging current setting terminal.

Description

Charger circuit with thermal regulation

The present invention relates to a charger circuit, and more particularly to a charger circuit with thermal regulation.

A charger circuit, such as a linear charger, generally includes a constant current charging circuit and a constant voltage charging circuit. A linear charger can charge a battery in a constant current mode by using the constant current charging circuit, and can charge a battery in a constant voltage mode by using the constant voltage charging circuit. As the charging current used to charge the battery becomes larger, the ambient temperature of the chip of the linear charger will increase, which may cause damage to the chip of the linear charger. A thermal regulation circuit can be coupled to the constant current charging circuit to control the temperature of the chip, and thus prevent the chip from being damaged due to high temperature.

A typical thermal regulation circuit can modulate one of the voltages at the negative or positive end of an amplifier in a constant current charging circuit through a zero temperature coefficient reference voltage of a linear charger and a temperature sensing voltage of a linear charger, wherein a setting resistor for setting the charging current is coupled to the positive end of the amplifier.

However, the above configurations for modulating the voltage of the thermal regulation circuit encounter different problems. In the configuration where the voltage at the positive terminal of the amplifier is modulated according to temperature, the shutdown temperature of the linear charger may change with different values of the set resistor. In other configurations where the voltage at the negative terminal of the amplifier is modulated according to temperature, the power stage of the linear charger may not shut down at higher temperatures.

The object of the present invention is to provide a charger circuit with thermal regulation to have a stable shutdown temperature.

In order to achieve the above-mentioned purpose, the present invention provides a charger circuit. The charger circuit includes a constant current charging circuit and a thermal regulation circuit. The constant current charging circuit is configured to generate a charging current, and the constant current charging circuit includes a charger input terminal for receiving an input voltage, a charging current setting terminal, a charger output terminal for outputting the charging current, a current mirror, and a feedback amplifier. The current mirror includes a reference current path between the charger input terminal and the charging current setting terminal and an output current path between the charger input terminal and the charger output terminal. The feedback amplifier has a positive terminal, a negative terminal for receiving a feedback reference voltage, and a feedback output terminal coupled to the current mirror. The thermal regulation circuit is coupled to the positive terminal of the feedback amplifier and the charging current setting terminal, and is configured to generate and modulate a thermal regulation voltage according to the temperature, and output the thermal regulation voltage between the positive terminal of the feedback amplifier and the charging current setting terminal.

In some embodiments of the charger circuit, the constant current charging circuit further includes: a first transistor, a second transistor, a third transistor and an operational amplifier. The first transistor has a reference current path coupled to the feedback output terminal and a control terminal. The second transistor has an output current path coupled to the feedback output terminal and a control terminal. The third transistor has a load path and a control terminal, wherein the reference current path is coupled to the charging current setting terminal through the load path of the third transistor. The operational amplifier has a negative terminal coupled to the reference current path, a positive terminal coupled to the output current path, and an output terminal coupled to the control terminal of the third transistor.

In some embodiments of the charger circuit, the constant current charging circuit further includes: a first P-type transistor, a second P-type transistor, a third P-type transistor and an operational amplifier. The first P-type transistor in the reference current path has a source terminal, a drain terminal and a gate terminal coupled to the input voltage. The second P-type transistor in the output current path has a source terminal, a drain terminal and a gate terminal coupled to the input voltage. The third P-type transistor in the reference current path has a source terminal coupled to the drain terminal of the first P-type transistor, a drain terminal and a gate terminal coupled to the charging current setting terminal. The operational amplifier has a negative terminal coupled to the source terminal of the third P-type transistor, a positive terminal coupled to the drain terminal of the second P-type transistor, and an output terminal coupled to the gate terminal of the third P-type transistor.

In some embodiments of the charger circuit, the thermal regulation circuit includes: a voltage-to-current converter and a thermal regulation voltage generating circuit. The voltage-to-current converter is configured to generate and modulate a thermal regulation current according to a temperature sensing voltage and a temperature reference voltage along with the temperature, and has a positive terminal coupled to the temperature sensing voltage, a negative terminal coupled to the temperature reference voltage, and an output terminal to output the thermal regulation current. The thermal regulation voltage generating circuit is configured to generate a thermal regulation voltage according to the thermal regulation current along with the temperature, and has a regulation input terminal coupled to the voltage-to-current converter, a first output terminal coupled to the positive terminal of the feedback amplifier, and a second output terminal coupled to the charging current setting terminal.

In some embodiments of the charger circuit, the voltage-to-current converter includes a transconductance amplifier to receive a temperature sensing voltage and a temperature reference voltage, and output a thermally regulated current based on the difference between the temperature sensing voltage and the temperature reference voltage.

In some embodiments of the charger circuit, the thermal regulation voltage generating circuit includes a first current source circuit, a second current source circuit, and an output resistor. The first current source circuit is configured to provide a current according to a thermal regulation current received from a regulation input terminal. The second current source circuit is configured to provide a current according to a thermal regulation current received from a regulation input terminal. The output resistor is coupled between the first current source circuit and the second current source circuit, wherein the output resistor has two ends, which are respectively coupled to a first output terminal and a second output terminal, wherein when a current flows through the output resistor, a cross-voltage generated by the output resistor is a thermal regulation voltage.

In some embodiments of the charger circuit, the thermal regulation circuit generates a thermal regulation voltage based on the difference between a temperature sensing voltage and a temperature reference voltage.

In some embodiments of the charger circuit, when the temperature sensing voltage is greater than the temperature reference voltage and the temperature represented by the temperature sensing voltage is less than a shutdown temperature for the charger circuit, the voltage at the charging current setting end is obtained based on the feedback reference voltage minus the thermal regulation voltage.

In some embodiments of the charger circuit, when the temperature represented by the temperature sensing voltage is equal to or greater than a shutdown temperature of the charger circuit, the thermal regulation voltage generated by the thermal regulation circuit is greater than the feedback reference voltage, so that the voltage at the charging current setting end is zero.

In some embodiments of the charger circuit, when the thermal regulation voltage generated by the thermal regulation circuit is greater than the feedback reference voltage, the feedback amplifier turns off the current mirror and the voltage at the charge current setting terminal is zero, so that the current mirror does not generate a charge current.

In some embodiments of the charger circuit, the charger circuit has a shutdown temperature that is independent of the value of the setting resistor coupled to the charging current setting terminal.

10: Charger circuit

10A: Charger circuit

90:Battery

100: Constant current charging circuit

102: Feedback amplifier

104: Operational amplifier

200: Thermal regulation circuit

200A: Thermal regulation circuit

210: Voltage-to-current converter

210A: Voltage-to-current converter

211: Transduction amplifier

220: Thermal regulation voltage generating circuit

220A: Thermal regulation voltage generating circuit

221: First current source circuit

223: Second current source circuit

I _BAT :Battery current

I _CS : Reference current

I _CT : Thermal Regulation Current

I _PS :Charging current

I _TM : Current

M _CS : First transistor

M _PS : Second transistor

M _CM : The third transistor

N _IN : Charger input terminal

N _ISET : Charging current setting terminal

N _OUT : Charger output terminal

R _ISET : Set resistance

_RT : Output resistance

TR: Temperature range

TR1: Temperature range

T _SD : Shutdown temperature

V _BAT :Battery voltage

V _{CA_REF} : Feedback reference voltage

V _DD : Supply voltage

V _G : Gate voltage

V _IN : Input voltage

V _MOD : Thermal Regulation Voltage

V _ISET : Setting voltage

V _{SEN_T} : Temperature sensing voltage

T _SD1 : Shutdown temperature

V _{TEMP_REF} : Temperature reference voltage

△V: Thermal regulation voltage

FIG1 is a schematic diagram illustrating a charger circuit with thermal regulation according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating thermal regulation of voltage in the charger circuit of FIG. 1 according to an embodiment of the present invention.

FIG3 is a diagram illustrating the structure of a thermal regulation circuit according to some embodiments of the present invention.

FIG4 is a schematic diagram illustrating a charger circuit with a thermal regulation circuit based on FIG1 and FIG3 according to an embodiment of the present invention.

FIG. 5 is an example diagram illustrating the thermal modulation of the associated voltage and current of the charger circuit shown in FIG. 4 according to an embodiment of the present invention.

In order to make it easier to understand the purpose, technical features and effects of the present invention, diagrams and embodiments are provided to illustrate the present invention in detail.

Please refer to FIG. 1 for an explanation of a charger circuit 10 with thermal regulation according to an embodiment of the present invention. As shown in FIG. 1 , the charger circuit 10 includes a constant current charging circuit 100 and a thermal regulation circuit 200.

The constant current charging circuit 100 is configured to generate a charging current to charge the battery 90. The constant current charging circuit 100 includes a charger input terminal N _IN for receiving an input voltage V _IN , a charging current setting terminal N _ISET for coupling to a setting resistor R _ISET , a charger output terminal N _OUT for outputting a charging current I _PS , a current mirror (e.g., formed using two or more transistors), and a feedback amplifier 102. The current mirror includes a reference current path for a reference current I _CS and a current mirror (e.g., formed using two or more transistors) for an output current path of the charging current I _PS . The feedback amplifier 102 has a positive terminal (e.g., represented by "+") for receiving a feedback reference voltage V _{CA_REF} , a negative terminal (e.g., represented by "-"), and a feedback output terminal coupled to the current mirror to control the current mirror. The reference current path is coupled between the charger input terminal N _IN and the charging current setting terminal N _ISET , and the output current path is coupled between the charger input terminal N _IN and the charger output terminal N _OUT .

In practical applications, the charger circuit 10 is implemented by a linear charger circuit and may further include a constant voltage charging circuit (not shown). In this way, the battery 90 is charged with a battery voltage V _BAT and a battery current I _BAT . Since the present invention focuses on thermal regulation for a constant current charging circuit, the constant voltage charging circuit is not described in detail herein.

In some embodiments of the charger circuit 10, the constant current charging circuit 100 further includes: a first transistor M _CS , a second transistor M _PS , a third transistor M _CM, and an operational amplifier 104. The first transistor M _CS is set in the reference current path. The second transistor M _PS is set in the output current path. The control end of the first transistor M _CS and the control end of the second transistor M _PS are coupled to the feedback output end. The third transistor M _CM is set in the reference current path and coupled between the first transistor M _CS and the charging current setting end N _ISET . The operational amplifier 104 has an output end coupled to the negative end of the reference current path, the positive end of the output current path, and the control end of the third transistor M _CM .

For example, as shown in Figure 1, the first transistor M _CS is implemented by using a first P-type transistor such as a PMOS transistor in a reference current path, and the first transistor M _CS has a source terminal, a drain terminal and a gate terminal, wherein the source terminal is coupled to the input voltage V _IN (or the charger input terminal N _IN ), the drain terminal is in the reference current path, and the gate terminal serves as the control terminal of the first transistor M _CS . For example, as shown in Figure 1, the second transistor _MPS is implemented by using a second P-type transistor such as a PMOS transistor in the output current path, and the second transistor _MPS has its source, drain and gate terminals, wherein the source terminal is coupled to the input voltage V _IN (or the charger input terminal N _IN ), the drain terminal is in the output current path, and the gate terminal serves as the control terminal of the second transistor _MPS coupled to the control terminal of the first transistor M _CS . For example, as shown in FIG. 1 , the third transistor M _CM is implemented by using a third P-type transistor such as a PMOS transistor in the reference current path, and the third transistor M _CM has a source terminal, a drain terminal, and a gate terminal, wherein the source terminal is coupled to the drain terminal of the first transistor M _CS , and the drain terminal is coupled to the charge current setting terminal N _ISET . For example, the operational amplifier 104 has a negative terminal coupled to the source terminal of the third transistor M _CM , a positive terminal coupled to the drain terminal of the second transistor M _PS , and an output terminal coupled to the gate terminal of the third transistor M _CM .

As shown in FIG. 1 , the thermal regulation circuit 200 is coupled to the positive terminal of the feedback amplifier 102 and the charge current setting terminal N _ISET , and is configured to generate and modulate the thermal regulation voltage V _MOD according to temperature, and output the thermal regulation voltage V _MOD between the positive terminal of the feedback amplifier 102 and the charge current setting terminal N _ISET . In addition, the thermal regulation circuit 200 can be implemented to receive a temperature sensing voltage V _{SEN_T} and a temperature reference voltage V _{TEMP_REF} and modulate the thermal regulation voltage V _MOD according to the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} , wherein the temperature reference voltage V _{TEMP_REF} is close to a zero temperature coefficient reference voltage and the temperature sensing voltage V _{SEN_T} is a temperature-dependent voltage. For example, the temperature sensing voltage V _{SEN_T} increases as the temperature increases and decreases as the temperature decreases, wherein the temperature may represent the ambient temperature of the charger circuit.

其中，V_ISET為在充電電流設定端N_ISET的設定電壓，並且V_MOD表示為△V。上述方程式可以如下的方程式(記作Eq.2)來表示：

根據上述方程式，可以隨著溫度藉由熱調節電壓V_MOD的調變來將在充電電流設定端N_ISET的設定電壓V_ISET降低或減少至零。然後，參考電流I_CS以及充電電流I_PS也可以降低或減少至零。 For the positive and negative terminals of the feedback amplifier 102, the voltage at the positive terminal (e.g., the sum of the voltage at the charge current setting terminal N _ISET and the thermal regulation voltage V _MOD ) is approximately equal to the voltage at the negative terminal (e.g., the feedback reference voltage V _{CA — REF} ), as shown in the following equation (denoted as Eq. 1):

Wherein, V _ISET is the set voltage at the charging current setting terminal N _ISET , and V _MOD is represented by △V. The above equation can be represented by the following equation (denoted as Eq. 2):

According to the above equation, the setting voltage V _ISET at the charging current setting terminal N _ISET can be reduced or decreased to zero by adjusting the thermal regulation voltage V _MOD along with the temperature. Then, the reference current I _CS and the charging current I _PS can also be reduced or decreased to zero.

Accordingly, the thermal regulation circuit 200 can be implemented to generate and modulate the thermal regulation voltage V _MOD according to the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} , so that when the temperature rises, the set voltage V _ISET can be reduced from the voltage level of the feedback reference voltage V _{CA_REF} , and can be reduced to zero according to the required stable shutdown temperature.

Please refer to FIG. 2 , which illustrates the thermal regulation of the thermal regulation voltage V _MOD of the charger circuit of FIG. 1 according to one embodiment of the present invention. As shown in FIG. 2 , the relationship between the feedback reference voltage V _{CA_REF} , the set voltage V _ISET , and the thermal regulation voltage V _MOD (or also expressed as ΔV) relative to the temperature is shown. When the temperature is less than the temperature range TR relative to the shutdown temperature T _SD , the thermal regulation voltage V _MOD (or expressed as ΔV) is zero and the set voltage V _ISET is approximately equal to the feedback reference voltage V _{CA_REF} . As the temperature increases and enters the temperature range TR, the thermal regulation voltage V _MOD starts to rise from zero and the set voltage V _ISET starts to fall. When the temperature is equal to the shutdown temperature T _SD , the set voltage V _ISET is equal to zero. When the temperature is greater than the shutdown temperature T _SD , the set voltage V _ISET remains zero and the feedback amplifier 102 outputs an output voltage (e.g., a high level voltage) to turn off the first transistor M _CS and the second transistor M _PS . In this way, the reference current I _CS and the charging current I _PS can be reduced to zero when the shutdown temperature is required to be stable.

In order to achieve a stable shutdown temperature, the thermal regulation circuit 200 can be implemented by generating and modulating the thermal regulation voltage V _MOD in various ways according to the voltage relationship illustrated in FIG2 . Some embodiments of the thermal regulation circuit 200 are described below.

3, the structure of the thermal regulation circuit 200 is illustrated according to some embodiments of the present invention. In some embodiments, the thermal regulation circuit 200 includes a voltage-to-current converter 210 and a thermal regulation voltage generating circuit 220. The voltage-to-current converter 210 is configured to generate and modulate the thermal regulation current according to the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} along with the temperature, and has a positive terminal coupled to the temperature sensing voltage V _{SEN_T} , a negative terminal coupled to the temperature reference voltage V _{TEMP_REF} , and an output terminal for outputting the thermal regulation current. The thermal regulation voltage generating circuit 220 is configured to generate a thermal regulation voltage V _MOD according to the temperature based on the thermal regulation current, and has a regulation input terminal coupled to the voltage-to-current converter 210, the first output terminal, and the second output terminal. The thermal regulation voltage generating circuit 220 outputs the thermal regulation voltage V _MOD through the first output terminal and the second output terminal. The first output terminal and the second output terminal of the thermal regulation voltage generating circuit 220 serve as output terminals of the thermal regulation circuit 200, and are respectively coupled to the positive terminal of the feedback amplifier 102 and the charging current setting terminal N _ISET .

In some embodiments of the charger circuit of FIG. 1 or FIG. 3 , the thermal regulation circuit 200 generates the thermal regulation voltage V _MOD according to the difference between the temperature sensing voltage V _{SEN — T} and the temperature reference voltage V _{TEMP — REF} .

In some embodiments of the charger circuit based on FIG. 1 or FIG. 3 , when the temperature sensing voltage V _{SEN_T} is greater than the temperature reference voltage V _{TEMP_REF} and the temperature indicated by the temperature sensing voltage V _{SEN_T} is less than the shutdown temperature T _SD of the charger circuit, the set voltage V _ISET at the charging current setting terminal N _ISET is obtained according to the feedback reference voltage V _{CA_REF} minus the thermal regulation voltage V _MOD .

In some embodiments of the charger circuit based on FIG. 1 or FIG. 3 , when the temperature represented by the temperature sensing voltage V _{SEN_T} is equal to or greater than the shutdown temperature T _SD of the charger circuit 10 , the thermal regulation voltage V _MOD generated by the thermal regulation circuit 200 is greater than the feedback reference voltage V _{CA — REF} , so that the set voltage V _ISET at the charging current setting terminal N _ISET is zero.

In some embodiments of the charger circuit based on FIG. 1 or FIG. 3 , when the thermal regulation voltage V _MOD generated by the thermal regulation circuit 200 is greater than the feedback reference voltage V _{CA — REF} , the feedback amplifier 102 turns off the current mirror of the fixed current charging circuit 100, and the set voltage V _ISET at the charging current setting terminal N _ISET is zero, so that the current mirror does not generate a charging current.

In some embodiments of the charger circuit based on FIG. 1 or FIG. 3 , the charger circuit 10 has a shutdown temperature that is independent of the value of the setting resistor R _ISET coupled to the charging current setting terminal N _ISET .

Please refer to FIG. 4, which illustrates a charger circuit 10A with thermal regulation based on FIG. 1 and FIG. 3 according to an embodiment of the present invention. In FIG. 4, the charger circuit 10A includes a constant current charging circuit 100 as shown in FIG. 1 and a thermal regulation circuit 200A based on the structure shown in FIG. 3. The thermal regulation circuit 200A includes a voltage-current converter 210A and a thermal regulation voltage generating circuit 220A.

As shown in FIG4 , the voltage-to-current converter 210A includes a transconductance amplifier 211 to receive the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} and output the thermal regulation current I _CT . For example, the transconductance amplifier 211 can be configured to output the thermal regulation current I _CT based on the gain (such as represented by G _TM ) of the transconductance amplifier ₂₁₁ multiplied by the difference between the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} when the temperature sensing voltage V SEN_T is greater than the temperature reference voltage V _{TEMP_REF} . The thermal regulation current I _CT can be expressed by the following equation (denoted as Eq. 3): I _CT =(V _{SEN_T} -V _{TEMP_REF} )G _TM (Eq. 3) Conversely, when the temperature sensing voltage V _{SEN_T} is less than or equal to the temperature reference voltage V _{TEMP_REF} , the thermal regulation current I _CT is zero or has a small value that can be omitted.

The thermal regulation voltage generating circuit 220A includes a first current source circuit 221, a second current source circuit 223, and an output resistor _RT . The first current source circuit 221 is configured to provide a current according to the thermal regulation current I _CT received from the regulation input terminal. For example, the first current source circuit 221 is a current-controlled current source, which is coupled between a first reference voltage (e.g., a supply voltage V _DD ) and a first output terminal of the thermal regulation voltage generating circuit 220A and is controlled according to the thermal regulation current I _CT . The second current source circuit 223 is configured to provide a current according to the thermal regulation current I _CT received from the regulation input terminal. For example, the second current source circuit 223 is a current-controlled current source, which is coupled between the second output terminal of the thermal regulation voltage generating circuit 220A and a second reference voltage (e.g., a ground voltage), and is controlled according to the thermal regulation current I _CT . The output resistor _RT is coupled between the first current source circuit 221 and the second current source circuit 223. For example, the output resistor _RT has two ends, which are respectively coupled to the first output terminal and the second output terminal of the thermal regulation voltage generating circuit 220A. The first output terminal and the second output terminal of the thermal regulation voltage generating circuit 220A serve as output terminals of the thermal regulation circuit 200A, and are respectively coupled to the positive terminal of the feedback amplifier 102 and the charging current setting terminal N _ISET . Thus, when the current (represented by I _TM ) flows through the output resistor _RT , the voltage across the output resistor _RT is the thermal regulation voltage V _MOD .

For illustration, assuming that in an example, the first current source 221 and the second current source 223 generate the same current by the thermal regulation current I _CT , the thermal regulation voltage V _MOD can be expressed by the following equation (denoted as Eq. 4) according to equation Eq. 3: V _MOD = (V _{SEN_T} - V _{TEMP_REF} ) G _TM R _T (Eq. 4) By equations Eq. 2 and Eq. 4, for this example, when the temperature is less than the shutdown temperature, the set voltage V _ISET at the charging current setting terminal N _ISET and its corresponding reference current I _CS (which is the current mirrored by the charging current I _PS ) can be expressed by the following equations (Eq. 5 and Eq. 6): V _ISET = V _{CA_REF} - (V _{SEN_T} - V _{TEMP_REF} ) G _TM R _T (Eq.5)

I _CS =V _ISET /R _ISET (Eq.6)

The above equations Eq.5 and Eq.6 indicate that when the temperature sensing voltage V _{SEN_T} is greater than the temperature reference voltage V _{TEMP_REF} , if the temperature is less than the shutdown temperature of the charger circuit 10A, the set voltage V _ISET at the charging current setting terminal N _ISET can be adjusted according to the temperature in a linear manner. In addition, when the temperature is equal to or greater than the shutdown temperature of the charger circuit 10A, the set voltage V _ISET can be set to zero to achieve the design requirements of the charger circuit 10A. For example, the parameter values V _{CA_REF} , V _{SEN_T} , V _{TEMP_REF} , G _TM and _RT can be designed according to equations Eq.5 and Eq.6 to achieve the adjustment of the design requirements of the charger circuit 10A and stabilize the shutdown temperature. For example, the charger circuit 10A can be configured to modulate the charging current _IPs with temperature and can operate according to the voltage relationship shown in FIG2. Accordingly, thermal regulation of a stable shutdown temperature can be achieved regardless of different values of the set resistor, and the circuit complexity of the control architecture of the thermal regulation is reduced.

Please refer to FIG. 5 , which illustrates an example of thermal modulation of voltage and current associated with the charger circuit 10A shown in FIG. 4 according to some embodiments of the present invention. Assume that the charger input terminal N _IN is coupled to the input voltage V _IN of 5V. As shown in FIG. 5 , by using the thermal regulation voltage V _MOD to modulate with temperature, when the temperature is within the temperature range TR1, the set voltage V _ISET becomes linear with the temperature modulation, the temperature range TR1 helps the charging current I _PS to modulate with temperature, and when the temperature is within the temperature range TR1, the charging current I _PS is also linear with the temperature modulation. In addition, when the charging current I _PS is configured to have different initial current values (e.g., 500 mA, 200 mA, 100 mA, and 50 mA) by using the setting resistor R _ISET having different resistance values, the shutdown temperature T _SD1 of the charger circuit 10A can be stabilized and remain unchanged. That is, regardless of the different resistance values of the setting resistor R _ISET , the shutdown voltage of the charger circuit 10A remains unchanged. For different gate voltages V _G corresponding to different initial current values of the charging current I _PS (e.g., 500 mA, 200 mA, 100 mA, and 50 mA), the current mirror (or power stage) of the charger circuit 10A is turned off at a higher temperature than the shutdown temperature (e.g., the gate voltage V _G is approximately equal to the input voltage V _IN at high temperature), resulting in the charging current I _PS being zero.

In some embodiments, the charging circuit (e.g., FIG. 1, FIG. 4, or any of the above examples) may have a constant current charging circuit with other configurations or implementations. For example, the reference current path and the output current path of the constant current charging circuit may be implemented as transistors including other types of transistors or by using different types of transistors (e.g., N-type transistors; or both P-type transistors and N-type transistors), and the thermal regulation circuit may be adjusted or configured to conform to the voltage relationship shown above (e.g., FIG. 2 or an example based on FIG. 2) when appropriate.

In other embodiments, for example, a charger circuit according to FIG. 1 , FIG. 4 , or any of the above examples may be implemented as a chip or implemented inside a chip for charging an energy storage device such as a battery. For example, the chip may include a setting resistor R _ISET or a circuit for providing a feedback reference voltage V _{CA_REF} (such as implemented by a voltage source), or both. In some examples, the chip may be implemented with one or more specific terminals, such as a terminal connected to the charging current setting terminal N _ISET and/or a terminal connected to the negative terminal of the feedback amplifier 102. In this way, the chip can exclude the setting resistor R _ISET or exclude the circuit for providing the feedback reference voltage V _{CA — REF} , or exclude both, wherein the setting resistor R _ISET or the circuit for providing the feedback reference voltage V _{CA — REF} is an environmental element or an external element that can be coupled to the corresponding terminal of the chip.

Although the present invention has been described through various embodiments, a person having ordinary knowledge in the field to which the present invention belongs can make many modifications and changes to it without departing from the scope and spirit of the patent application scope of the present invention.

10: Charger circuit

90:Battery

100: Constant current charging circuit

102: Feedback amplifier

104: Operational amplifier

200: Thermal regulation circuit

I _BAT :Battery current

I _CS : Reference current

I _PS :Charging current

M _CS : First transistor

M _PS : Second transistor

M _CM : The third transistor

N _IN : Charger input terminal

N _ISET : Charging current setting terminal

N _OUT : Charger output terminal

R _ISET : Set resistance

V _BAT :Battery voltage

V _{CA_REF} : Feedback reference voltage

V _IN : Input voltage

V _MOD : Thermal Regulation Voltage

V _G : Gate voltage

V _ISET : Setting voltage

V _{SEN_T} : Temperature sensing voltage

V _{TEMP_REF} : Temperature reference voltage

Claims (11)

A charger circuit includes: a constant current charging circuit for generating a charging current, the constant current charging circuit including a charger input terminal for receiving an input voltage, a charging current setting terminal, a charger output terminal for outputting the charging current, a current mirror, and a feedback amplifier, the current mirror including a reference current path between the charger input terminal and the charging current setting terminal and a reference current path between the charger input terminal and the charger. An output current path between the positive terminal and the output terminal of the feedback amplifier, the feedback amplifier having a positive terminal, a negative terminal for receiving a feedback reference voltage, and a feedback output terminal coupled to the current mirror; and a thermal regulation circuit coupled to the positive terminal of the feedback amplifier and the charging current setting terminal, the thermal regulation circuit is used to generate and modulate a thermal regulation voltage with temperature, and output the thermal regulation voltage between the positive terminal of the feedback amplifier and the charging current setting terminal. A charger circuit as described in claim 1, wherein the constant current charging circuit further comprises: a first transistor, arranged in the reference current path; a second transistor, arranged in the output current path, wherein a control terminal of the first transistor and a control terminal of the second transistor are coupled to the feedback output terminal; a third transistor, arranged in the reference current path and coupled between the first transistor and the charging current setting terminal; and an operational amplifier having a negative terminal coupled to the reference current path, a positive terminal coupled to the output current path, and an output terminal coupled to a control terminal of the third transistor. A charger circuit as described in claim 1, wherein the constant current charging circuit further comprises: a first P-type transistor, which is in the reference current path, wherein a source terminal of the first P-type transistor is coupled to the input voltage; a second P-type transistor, which is in the output current path, wherein a source terminal of the second P-type transistor is coupled to the input voltage, a drain terminal of the second P-type transistor is coupled to the charger output terminal, and a gate terminal of the second P-type transistor is coupled to the first a gate terminal of a P-type transistor; a third P-type transistor in the reference current path, wherein a source terminal of the third P-type transistor is coupled to a drain terminal of the first P-type transistor, and a drain terminal of the third P-type transistor is coupled to the charging current setting terminal; and an operational amplifier having a negative terminal coupled to the source terminal of the third P-type transistor, a positive terminal coupled to the drain terminal of the second P-type transistor, and an output terminal coupled to a gate terminal of the third P-type transistor. A charger circuit as described in claim 1, wherein the thermal regulation circuit comprises: a voltage-to-current converter configured to generate and modulate a thermal regulation current according to a temperature sensing voltage and a temperature reference voltage along with the temperature, and the voltage-to-current converter has a positive terminal coupled to the temperature sensing voltage, a negative terminal coupled to the temperature reference voltage, and an output terminal for outputting the temperature sensing voltage. Output the thermal regulation current; and a thermal regulation voltage generating circuit, configured to generate the thermal regulation voltage according to the thermal regulation current along with the temperature, and the thermal regulation voltage generating circuit has a regulation input terminal coupled to the voltage-to-current converter, a first output terminal coupled to the positive terminal of the feedback amplifier, and a second output terminal coupled to the charging current setting terminal. A charger circuit as described in claim 4, wherein the voltage-to-current converter includes a transconductance amplifier, the transconductance amplifier is used to receive the temperature sensing voltage and the temperature reference voltage, and is used to output the thermal regulation current based on the difference between the temperature sensing voltage and the temperature reference voltage. A charger circuit as described in claim 4, wherein the thermal regulation voltage generating circuit comprises: a first current source circuit for providing current according to the thermal regulation current received from the regulation input terminal; a second current source circuit for providing current according to the thermal regulation current received from the regulation input terminal; and an output resistor coupled between the first current source circuit and the second current source circuit, wherein the output resistor has two ends, the two ends are respectively coupled to the first output terminal and the second output terminal, wherein when the current flows through the output resistor, the cross-voltage generated by the output resistor is the thermal regulation voltage. A charger circuit as described in claim 1, wherein the thermal regulation circuit generates the thermal regulation voltage based on the difference between a temperature sensing voltage and a temperature reference voltage. A charger circuit as described in claim 7, wherein when the temperature sensing voltage is greater than the temperature reference voltage and the temperature represented by the temperature sensing voltage is less than a shutdown temperature for the charger circuit, the voltage at the charging current setting end is obtained by subtracting the thermal regulation voltage from the feedback reference voltage. A charger circuit as described in claim 7, wherein when the temperature represented by the temperature sensing voltage is equal to or greater than a shutdown temperature of the charger circuit, the thermal regulation voltage generated by the thermal regulation circuit is greater than the feedback reference voltage, so that the voltage at the charging current setting end is zero. A charger circuit as described in claim 7, wherein when the thermal regulation voltage generated by the thermal regulation circuit is greater than the feedback reference voltage, the feedback amplifier turns off the current mirror, and the voltage at the charging current setting end is zero, so that the current mirror does not generate a charging current. A charger circuit as described in claim 7, wherein the charger circuit has a shutdown temperature that is independent of the value of a setting resistor coupled to the charging current setting terminal.