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US 9,431,845 B2Granted
Switching charger, the control circuit and the control method thereof
AssigneeChengdu Monolithic Power Systems Co., Ltd.
InventorsMin Xu, Zhengui Bai, Xiaoqing Li, Yuancheng Ren
Life of this patent
Estimating the term…
Abstract
A switching charger having a control circuit configured to provide a control signal; a power stage turned ON and OFF by the control signal; an inductor coupled between the power stage and a load; and an output capacitor coupled in parallel with the load; a current sense circuit integrated to the control circuit to sense a current flowing through the power stage.
Claims17
A switching charger, comprising:
- a control circuit configured to provide a control signal;
- a power stage having a high-side power switch and a low-side power switch coupled in series, the high-side power switch and the low-side power switch turned ON and OFF alternatively by the control signal;
- an inductor having a first terminal coupled to the connection of the high-side power switch and the low-side power switch, and a second terminal coupled to a load;
- and
- an output capacitor having a first terminal coupled to the second terminal of the inductor, and a second terminal coupled to a reference ground;
- a current sense circuit integrated to the control circuit, wherein the current sense circuit has a first input terminal coupled to the high-side power switch, a second input terminal coupled to the low-side power switch, a first output terminal configured to generate a high-side current sense signal indicating the current flowing through the high-side power switch, and a second output terminal configured to generate a low-side current sense signal indicating the current flowing through the low-side power switch;
- wherein the control circuit comprises:
- a feedback amplifier having a first input terminal configured to receive a feedback signal indicating the charging voltage, a second input terminal configured to receive a feedback reference signal, and an output terminal configured to generate a amplified feedback signal based on the feedback signal and the feedback reference signal;
- a select circuit having a first input terminal configured to receive a current reference signal, a second input terminal coupled to the feedback amplifier to receive the amplified feedback signal, and an output terminal configured to generate a current control signal based on the current reference signal and the amplified feedback signal, wherein the current control signal is the lower value of the current reference signal and the amplified feedback signal;
- a hysteretic control circuit having a first input terminal coupled to the output terminal of the select circuit to receive the current control signal, a second input terminal configured to receive the input voltage, a third input terminal configured to receive the charging voltage, a fourth input terminal coupled to the output terminal of the control circuit to receive the control signal, and a fifth input terminal configured to receive a frequency control signal having pulses at moment when the high-side power switch is turned ON, wherein based on the current control signal, the input voltage, the charging voltage, the control signal and the frequency control signal, the hysteretic control circuit provides a lower limit signal via a first output terminal, and a higher limit signal via a second output terminal;
- a comparison circuit having a first input terminal coupled to the first output terminal of the hysteretic control circuit to receive the lower limit signal, a second input terminal coupled to the second output terminal of the hysteretic control circuit to receive the higher limit signal, a third input terminal coupled to the first output terminal of the current sense circuit to receive the high-side current sense signal, a fourth input terminal coupled to the second output terminal of the current sense circuit to receive the low-side current sense signal, and based on the lower limit signal, the higher limit signal, the high-side current sense signal and the low-side current sense signal, the comparison circuit provides a set signal via a first output terminal, and a reset signal via a second output terminal;
- and
- a logic circuit having a set terminal coupled to the comparison circuit to receive the set signal, a reset terminal coupled to the comparison circuit to receive the reset signal, and an output terminal configured to generate the control signal based on the set signal and the reset signal.
10 more elements
A control circuit for a switching charger, wherein the switching charger has a high-side power switch and a low-side power switch, the control circuit comprising:
- a feedback amplifier having a first input terminal configured to receive a feedback signal indicating the charging voltage, a second input terminal configured to receive a feedback reference signal, and an output terminal configured to generate a amplified feedback signal based on the feedback signal and the feedback reference signal;
- a select circuit having a first input terminal configured to receive a current reference signal, a second input terminal coupled to the feedback amplifier to receive the amplified feedback signal, and an output terminal configured to generate a current control signal based on the current reference signal and the amplified feedback signal, wherein the current control signal is the lower value of the current reference signal and the amplified feedback signal;
- a hysteretic control circuit having a first input terminal coupled to the output terminal of the select circuit to receive the current control signal, a second input terminal configured to receive the input voltage, a third input terminal configured to receive the charging voltage, a fourth input terminal coupled to the output terminal of the control circuit to receive the control signal, and a fifth input terminal configured to receive a frequency control signal having pulses at moment when the power stage is turned ON, wherein based on the current control signal, the input voltage, the charging voltage, the control signal and the frequency control signal, the hysteretic control circuit provides a lower limit signal via a first output terminal, and a higher limit signal via a second output terminal;
- a current sense circuit having a first input terminal coupled to the high-side power switch, a second input terminal coupled to the low-side power switch, a first output terminal configured to generate a high-side current sense signal indicating a current flowing through the high-side power switch, and a second output terminal configured to generate a low-side current sense signal indicating a current flowing through the low-side power switch;
- a comparison circuit having a first input terminal coupled to the first output terminal of the hysteretic control circuit to receive the lower limit signal, a second input terminal coupled to the second output terminal of the hysteretic control circuit to receive the higher limit signal, a third input terminal coupled to the first output terminal to receive the high-side current sense signal, a fourth input terminal coupled to the second output terminal to receive the low-side current sense signal, and based on the lower limit signal, the higher limit signal, the high-side current sense signal and the low-side current sense signal, the comparison circuit provides a set signal via a first output terminal, and a reset signal via a second output terminal;
- and
- a logic circuit having a set terminal coupled to the comparison circuit to receive the set signal, a reset terminal coupled to the comparison circuit to receive the reset signal, and an output terminal configured to generate the control signal based on the set signal and the reset signal.
4 more elements
A control method for a switching charger, wherein the switching charger has a high-side power switch and a low-side power switch, the control method comprising:
- generating a higher limit signal and a lower limit signal;
- sensing a current flowing through the high-side power switch to generate a high-side current sense signal;
- sensing a current flowing through the low-side power switch to generate a low-side current sense signal;
- and
- turning OFF the high-side power switch when the high-side current sense signal is higher than the higher limit signal, and turning ON the high-side power switch when the low-side current sense signal is lower than the lower limit signal;
- wherein the step of generating a higher limit signal and a lower limit signal comprises:
- amplifying an error between a feedback signal indicating an output voltage of the switching charger and a feedback reference signal to generate an amplified feedback signal;
- selecting the smaller value of the amplified feedback signal and a current reference signal to be a current control signal;
- generating a hysteretic window signal;
- and
- generating the higher limit signal and the lower limit signal based on the current control signal and the hysteretic window signal.
8 more elements
Dependencies are inferred from the claim text.