TWI796951B - Linear charger - Google Patents

Abstract

A linear charger includes a constant current charging circuit and a thermal regulation circuit. The constant current charging circuit is arranged to generate a charging current, and includes a first transconductance amplifier, wherein the first transconductance amplifier has a positive terminal, a negative terminal, and an output terminal. The thermal regulation circuit is coupled to the output terminal and the negative terminal of the first transconductance amplifier, and is arranged to generate and modulate a thermal regulation current and an amplifier reference voltage with temperature, and transmit the thermal regulation current and the amplifier reference voltage to the output terminal and the negative terminal of the first transconductance amplifier, respectively.

Description

linear charger

The present invention relates to linear chargers, and more particularly to linear chargers with thermal regulation circuits.

The linear charger can include a constant current charging circuit and a constant voltage charging circuit, and the battery can be charged in the constant current mode by the constant current charging circuit, and the battery can be charged in the constant voltage mode by the constant voltage charging circuit Charge. When the charging current for charging 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. Therefore, the thermal regulation circuit can be coupled to the constant current charging circuit to Control the temperature of the wafer.

A typical thermal regulation circuit usually only uses the zero-temperature coefficient reference voltage of the linear charger and the temperature sensing voltage to regulate the voltage at the positive terminal of the amplifier or the negative terminal of the amplifier. One of the voltages, wherein a setting resistor for setting the charging current is coupled to the positive terminal of the amplifier. However, some problems may occur. If only the temperature is used to adjust the voltage of the positive terminal of the amplifier, the shutdown temperature of the linear charger may vary with the value of the setting resistor; if only the temperature is used to adjust the voltage of the negative terminal of the amplifier , since in constant current mode the The offset voltage (offset voltage), the power supply stage (power stage) of the linear charger may not be able to be turned off at high temperature. In addition, the voltage regulation of the negative terminal of the amplifier using temperature is nonlinear, which makes it very difficult to estimate the charging current at different temperatures. Therefore, a novel linear charger with a thermal regulation mechanism is highly needed to Solve the above problems.

Therefore, one of the objectives of the present invention is to provide a linear charger with a thermal regulation circuit to solve the above problems.

According to one embodiment of the present invention, a linear charger is provided. The linear charger may include a constant current charging circuit and a thermal regulation circuit, the constant current charging circuit may be used to generate a charging current, and may include a first transconductance amplifier, wherein the first transconductance amplifier has a positive terminal, a Negative terminal and an output terminal. The thermal regulation circuit can be coupled to the output terminal and the negative terminal of the first transconductance amplifier, and can be used to use temperature to generate and modulate a thermal regulation current and an amplifier reference voltage, and transmit the thermal regulation current and the amplifier reference voltage respectively To the output terminal and the negative terminal of the first transconductance amplifier.

One of the advantages of the present invention is that the shutdown temperature of the linear charger of the present invention is constant for different values of the setting resistor used to set the charging current, wherein the setting resistor is coupled to a constant voltage of the linear charger. The positive terminal of the transconductance amplifier in the current charging circuit. By utilizing the temperature to modulate the thermally regulated current, the setting voltage modulation of the positive terminal of the transconductance amplifier in the constant current charging circuit of the linear charger using the temperature can become linear, which makes it possible to estimate the magnitude of the charging current at different temperatures becomes easier, and the charge current modulation using temperature is linear, in addition, for the charge current corresponding to different current values, the shutdown temperature of the linear charger is constant, and the power supply of the linear charger The supply stage is guaranteed to be shut down at high temperatures.

10,30: Linear Charger

100,300: constant current charging circuit

101,301: battery

102,200,302: thermal regulation circuit

104,202,208,304,308,314: transconductance amplifier

106, 306: operational amplifiers

V _{SEN_T} : temperature sensing voltage

V _{TEMP_REF} : temperature reference voltage

V _REF : amplifier reference voltage

V _IN : input voltage

V _G : gate voltage

GND: ground voltage

I ₁ : charging current

I ₂ : thermal regulation current

R _ISET : set resistance

P1, P2, P3: P-type transistors

204,310: Amplifier reference voltage generation circuit

206,312: Voltage source

R ₁ , R ₂ : resistance

V _ISET : set voltage

FIG. 1 is a schematic diagram of a linear charger according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a thermal regulation circuit according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a linear charger with the thermal regulation circuit shown in FIG. 2 according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing the relationship between the offset voltage and the setting voltage of the linear charger shown in FIG. 3 and the modulation of the reference voltage of the amplifier using temperature according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of modulation of relative current and voltage of the linear charger shown in FIG. 3 using temperature according to an embodiment of the present invention.

FIG. 1 is a schematic diagram of a linear charger 10 according to an embodiment of the present invention. As shown in Figure 1, the linear charger 10 may include a constant current charging circuit 100 and a thermal regulation circuit 102. In fact, the linear charger 10 may additionally include a constant voltage charging circuit (not shown), because the focus of the present invention It is for the thermal regulation design of the constant current charging circuit, therefore, for the sake of brevity, the content about the constant voltage charging circuit will not be described here.

The constant current charging circuit 100 may include a plurality of P-type transistors P1 , P2 and P3 , a transconductance amplifier 104 , an operational amplifier 106 and a setting resistor R _ISET . The P-type transistor P1 has a source terminal coupled to a first reference voltage (such as the input voltage V _IN ), the P-type transistor P2 has a source terminal coupled to the first reference voltage (such as the input voltage V _IN ), and A gate terminal coupled to the gate terminal of the P-type transistor P1, wherein the gate voltage V _G is the voltage of a node between the gate terminal of the P-type transistor P1 and the gate terminal of the P-type transistor P2, and charging The current _I1 is output by a drain terminal of the P-type transistor P2. The P-type transistor P3 has a source coupled to the drain of the P-type transistor P1.

The transconductance amplifier 104 has a positive terminal (+) coupled to the drain terminal of the P-type transistor P3, a negative terminal (-) coupled to the amplifier reference voltage V _REF , and a gate terminal coupled to the gate terminal of the P-type transistor P1. an output terminal. The operational amplifier 106 has a positive terminal (+) coupled to the source terminal of the P-type transistor P3, a negative terminal (-) coupled to the drain terminal of the P-type transistor P2 and the battery 101, and a negative terminal (-) coupled to the P-type transistor P3. An output terminal of the gate terminal of the crystal P3. The setting resistor R _ISET has a first terminal coupled to the positive terminal of the transconductance amplifier 104 and a second terminal coupled to a second reference voltage (such as the ground voltage GND), and can be used to set the charging current _I1 of the battery 101 .

The thermal regulation circuit 102 can be coupled to the output terminal and the negative terminal of the transconductance amplifier 104, and can be used to generate and adjust the thermal regulation current I ₂ and the amplifier reference voltage V _REF using temperature, and to connect the thermal regulation current I ₂ to the amplifier The reference voltage V _RE is sent to the output terminal and the negative terminal of the transconductance amplifier 104 respectively. In addition, the thermal regulation circuit 102 can receive the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} , and according to the temperature sensing voltage V _{SEN_T} and the temperature reference The voltage V _{TEMP_REF} is used to adjust the thermal regulation current I ₂ and the amplifier reference voltage V _REF , wherein the temperature reference voltage V _{TEMP_REF} is close to the zero-temperature coefficient reference voltage (zero-temperature coefficient reference voltage), and the temperature sensing voltage V _{SEN_T} is related to temperature dependent voltage. For example, the temperature sensing voltage V _{SEN_T} increases as the temperature increases and decreases as the temperature decreases.

FIG. 2 is a schematic diagram of a thermal regulation circuit 200 according to an embodiment of the present invention. For example, the thermal regulation circuit 102 shown in FIG. 1 can be realized by the thermal regulation circuit 200 shown in FIG. 2 , but the present invention is not limited thereto. As shown in FIG. 2, the thermal regulation circuit 200 may include a transconductance amplifier 202 and an amplifier reference voltage generating circuit 204. The transconductance amplifier 202 may be used to generate and utilize temperature according to the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} . To adjust the thermal regulation current I ₂ , in addition, the transconductance amplifier 202 has a positive terminal (+) coupled to the temperature sensing voltage V _{SEN_T} and a negative terminal (-) coupled to the temperature reference voltage V _{TEMP_REF} , therefore, The modulation of the thermal regulation current I ₂ using temperature can be expressed by the following equation: I ₂ =Max[0 , (V _{SEN_T} −V _{TEMP_REF} )G ₂ ] where G ₂ is the transconductance value of the transconductance amplifier 202 .

其中G₃係跨導放大器208的跨導值，R1係電阻R₁的電阻值，以及R2係電阻R₂的電阻值。 The amplifier reference voltage generating circuit 204 can be used to generate and modulate the amplifier reference voltage V _REF according to the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} , and can include a voltage source 206 , a transconductance amplifier 208 and a plurality of resistors R ₁ and R ₂ . The voltage source 206 has a first end coupled to a second reference voltage (such as the ground voltage GND), and is used to provide the voltage V _CC . The resistor _R1 has a first terminal coupled to a second terminal of the voltage source 206, wherein the amplifier reference voltage V _REF is output from a second terminal of the resistor _R1 . The resistor _R2 has a first terminal coupled to the second terminal of the resistor _R1 and a second terminal coupled to a second reference voltage (such as the ground voltage GND). The transconductance amplifier 208 has a positive terminal (+) coupled to the reference voltage V _{TEMP_REF} , a negative terminal (-) coupled to the temperature sensing voltage V _{SEN_T} , and an output terminal coupled to the second terminal of the resistor _R1 , and can be used to generate and modulate the amplifier _reference voltage V REF according to the temperature sensing voltage V _{SEN_T} and the temperature reference voltage V _{TEMP_REF} , the modulation of the amplifier reference voltage V _REF using temperature can be expressed by the following equation:

Where G ₃ is the transconductance value of the transconductance amplifier 208 , R1 is the resistance value of the resistor R ₁ , and R2 is the resistance value of the resistor R ₂ .

FIG. 3 is a schematic diagram of a linear charger 30 with the thermal regulation circuit 200 shown in FIG. 2 according to an embodiment of the present invention. As shown in FIG. 3, the linear charger 30 can include a constant current charging circuit 300 and a thermal regulation circuit 302, wherein the constant current charging circuit 300 and the thermal regulation circuit 302 can be respectively controlled by the constant current charging circuit 100 shown in FIG. and the thermal regulation circuit 200 shown in FIG. 2 to realize. The constant current charging circuit 300 may include a plurality of P-type transistors P1, P2, and P3, a transconductance amplifier 304, an operational amplifier 306, and a setting resistor R _ISET . For the sake of brevity, details of this embodiment will not be repeated here. Similar description. The thermal regulation circuit 302 may include a transconductance amplifier 308 and an amplifier reference voltage generating circuit 310, wherein the output terminal of the transconductance amplifier 308 may be coupled to the gate terminal of the P-type transistor P1 (that is, coupled to the gate terminal of the transconductance amplifier 304 output terminal). The amplifier reference voltage generating circuit 310 may include a voltage source 312, a transconductance amplifier 314, and a plurality of resistors R ₁ and R ₂ , wherein a node between the resistors R ₁ and R ₂ may be coupled to the transconductance amplifier 314 The output terminal and the negative terminal of the transconductance amplifier 304, for the sake of brevity, the similar description of this embodiment will not be repeated here.

Consider a case where the thermal regulation circuit 302 is modified to include only the amplifier reference voltage generation circuit 310 (that is, the thermal regulation circuit 302 only utilizes temperature to generate and modulate the amplifier reference voltage V _REF , and transmits the amplifier reference voltage V _REF to The case of the negative terminal of the transconductance amplifier 304), the modulation of the set voltage V _ISET at the positive terminal of the transconductance amplifier 304 is non-linear by using the temperature, wherein the modulation of the set voltage V _ISET is modulated by the amplifier reference voltage V _REF controlled by. In order to solve this problem, the thermal regulation circuit 302 can be configured to have a transconductance amplifier 308 and an amplifier reference voltage generating circuit 310 at the same time, and before the modulation of the amplifier reference voltage V _REF using temperature becomes non-linear, the thermal regulation can Current I ₂ to apply an offset voltage △V to the transconductance amplifier 304, so that the modulation of the set voltage V _ISET using the temperature becomes linear, wherein the voltage value of the offset voltage △V is equal to that of the amplifier at the same temperature The voltage value generated by subtracting the set voltage V _ISET from the reference voltage V _REF (ie ΔV=V _REF −V _ISET ).

其中(V_{SEN_T}-V_{TEMP_REF})

0，G₁係跨導放大器304的跨導值，以及G₂係跨導放大器308的跨導值。 FIG. 4 is a schematic diagram showing the relationship between the offset voltage ΔV and the setting voltage of the linear charger shown in FIG. 3 and the modulation of the reference voltage of the amplifier using temperature according to an embodiment of the present invention. As shown in Figure 4, the dotted line A is the modulation of the amplifier reference voltage V _REF using the temperature, and the solid line B is the modulation of the setting voltage V _ISET using the temperature, and the thermal regulation current I ₂ is modulated by using the temperature Before the modulation of the amplifier reference voltage V _REF using temperature becomes nonlinear (for example, before the temperature of the linear charger 30 reaches the temperature T0 shown in FIG. 4 ), an offset voltage can be applied to the transconductance amplifier 304 ΔV, and at the temperature T0, the set voltage V _ISET is equal to zero. The offset voltage △V can be calculated by the following equation:

where (V _{SEN_T} -V _{TEMP_REF} )

0, _G1 is the transconductance value of the transconductance amplifier 304, and _G2 is the transconductance value of the transconductance amplifier 308.

FIG. 5 is a schematic diagram of modulation of relative current and voltage of the linear charger 30 shown in FIG. 3 using temperature according to an embodiment of the present invention. Assuming that the input voltage V _IN coupled to the source terminal of the P-type transistor P1 and the source terminal of the P-type transistor P2 is equal to 5V, as shown in Figure 5, by using the temperature to adjust the thermal regulation current I ₂ , using The modulation of the temperature setting voltage V _ISET can become linear, which makes it easier to estimate the magnitude of the charging current _I1 at different temperatures, and the modulation of the charging current _I1 using the temperature is linear. In addition, for Corresponding to the charging current I ₁ of different current values (for example, 500 mA, 200 mA, 100 mA and 50 mA), the shutdown temperature of the linear charger 30 is constant. That is, for different values of the setting resistor _RISET , the shutdown temperature of the linear charger 30 is constant. For the gate voltage V _G corresponding to different current values of the charging current I ₁ (for example, 500 mA, 200 mA, 100 mA, and 50 mA), the power stage of the linear charger 30 It can be guaranteed to be turned off at high temperature (for example, at high temperature, the gate voltage V _G is equal to the input voltage V _IN ).

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

100: Constant current charging circuit

101: battery

102: Thermal regulation circuit

104: Transconductance amplifier

106: Operational amplifier

V _{SEN_T} : temperature sensing voltage

V _{TEMP_REF} : temperature reference voltage

V _REF : amplifier reference voltage

V _IN : input voltage

V _G : gate voltage

GND: ground voltage

I ₁ : charging current

I ₂ : thermal regulation current

R _ISET : set resistance

P1, P2, P3: P-type transistors

Claims (10)

A linear charger comprising: a constant current charging circuit for generating a charging current, wherein the constant current charging circuit comprises: a first transconductance amplifier having a positive terminal, a negative terminal and an output terminal; and a thermal regulation circuit, coupled to the output terminal and the negative terminal of the first transconductance amplifier, and used to use temperature to generate and adjust a thermal regulation current and an amplifier reference voltage, and respectively the thermal regulation The current and the amplifier reference voltage are sent to the output terminal and the negative terminal of the first transconductance amplifier. As the linear charger described in item 1 of the scope of patent application, wherein the constant current charging circuit further includes: a first P-type transistor having a source terminal coupled to a first reference voltage; a second P A type transistor having a source terminal coupled to the first reference voltage and a gate terminal coupled to a gate terminal of the first P-type transistor; a third P-type transistor having a gate terminal coupled to the first P-type transistor A source end of a drain end of a P-type transistor; an operational amplifier having a positive end coupled to the source end of the third P-type transistor and a drain end coupled to the second P-type transistor a negative terminal and an output terminal coupled to a gate terminal of the third P-type transistor; and a setting resistor having a first terminal coupled to the positive terminal of the first transconductance amplifier and coupled to a A second end of the second reference voltage; wherein the positive end of the first transconductance amplifier is coupled to a drain end of the third P-type transistor, and the negative end of the first transconductance amplifier is coupled to At the second reference voltage, the output terminal of the first transconductance amplifier is coupled to the gate terminal of the first P-type transistor. As for the linear charger described in item 2 of the scope of the patent application, wherein by using the thermal regulation circuit to adjust the thermal regulation current, for different values of the setting resistance, a shutdown temperature of the linear charger is different. changing. The linear charger as described in item 2 of the scope of the patent application, wherein the charging current is output from the sink end of the second P-type transistor, and the thermal regulation current is adjusted by utilizing the thermal regulation circuit, For the charging current corresponding to different current values, the shutdown temperature of one of the linear chargers is constant. The linear charger as described in item 4 of the scope of the patent application, wherein the modulation of the charging current by temperature is linear by using the thermal regulation circuit to modulate the thermal regulation current. The linear charger as described in Item 1 of the scope of the patent application, wherein the thermal regulation circuit includes: a second transconductance amplifier, which is used to generate and modulate the heat by using temperature according to a sensing voltage and a temperature reference voltage regulating current, and having a positive terminal coupled to the sensing voltage, a negative terminal coupled to the temperature reference voltage and an output terminal coupled to the output terminal of the first transconductance amplifier; and an amplifier reference The voltage generating circuit is coupled to the negative terminal of the first transconductance amplifier, and is used for generating and modulating the amplifier reference voltage by temperature according to the sensing voltage and the temperature reference voltage. The linear charger as described in item 6 of the patent application, wherein the reference voltage of the amplifier is The generating circuit includes: a voltage source having a first terminal coupled to a reference voltage; a first resistor having a first terminal coupled to a second terminal of the voltage source and coupled to the first a second terminal of the negative terminal of the transconductance amplifier; a second resistor having a first terminal coupled to the second terminal of the first resistor and a second terminal coupled to the reference voltage; and a first The three-transconductance amplifier is used to adjust the amplifier reference voltage by temperature according to the sensing voltage and the temperature reference voltage, and has a positive terminal coupled to the temperature reference voltage and a positive terminal coupled to the sensing voltage. a negative terminal and an output terminal coupled to the second terminal of the first resistor. The linear charger as described in item 1 of the scope of the patent application, wherein an offset voltage is applied to the first transconductance amplifier by using the thermal regulation current, and the utilization temperature of the positive end of the first transconductance amplifier is different A modulation of the set voltage is linear. In the linear charger described in claim 8 of the patent application, a voltage value of the offset voltage is equal to a voltage value generated by subtracting the set voltage from the reference voltage of the amplifier. In the linear charger described in claim 8 of the patent application, a current value of the thermal regulation current is equal to a current value generated by multiplying a gain of the first transconductance amplifier by the offset voltage.

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