Battery protection circuit and system
Techniques pertaining to battery protection circuits are disclosed. According to one embodiment of the present invention, the battery protection circuit includes a power button, a power detection circuit, a first switch coupled between the power button and the power detection circuit, the power detection circuit configured to output a power-off signal when either the first switch or the power button is in a switch-off state, a low-voltage detection circuit coupled with a battery and configured to detect whether a voltage of the battery is lower than a low-voltage detection threshold or not, and switch off the first switch to cut off an electric leakage path of the battery when the voltage of the battery is determined to be lower than the low-voltage detection threshold, and a power management circuit coupled with the power detection circuit and configured to cut off an electric discharge path of the battery to prohibit the battery from discharging when receiving the power-off signal.
1. A battery protection circuit, comprising:
a power button;
a power detection circuit;
a first switch coupled between the power button and the power detection circuit, the power detection circuit configured to output a power-off signal when either the first switch or the power button is in a switch-off state;
a low-voltage detection circuit coupled with a battery and configured to detect whether a voltage of the battery is lower than a low-voltage detection threshold or not, and switch off the first switch to cut off an electric leakage path of the battery when the voltage of the battery is determined to be lower than the low-voltage detection threshold; and
a power management circuit coupled with the power detection circuit and configured to cut off an electric discharge path of the battery to prohibit the battery from discharging when receiving the power-off signal.
2. The battery protection circuit according to claim 1 , wherein the low-voltage detection circuit comprises a first resistor, a second resistor, a current source, a switching transistor, a trigger and an inverter.
3. The battery protection circuit according to claim 2 , wherein the first resistor and the second resistor re coupled in series between a positive terminal and a negative terminal of the battery, the switching transistor has a control terminal coupled to an intermediate node between the first resistor and the second resistor, a collector terminal coupled with an output terminal of the current source and an input terminal of the trigger, an input terminal of the current source is coupled with the positive terminal of the battery, an output terminal of the trigger is coupled to an input terminal of the inverter, and the inverter outputs a voltage detection result, and the low-voltage detection threshold is determined by a ratio of a resistance value of the first resistor to a resistance value of the second resistor.
4. The battery protection circuit according to claim 1 , wherein the low-voltage detection circuit comprises a first resistor, a second resistor, a current source, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a fifth switching transistor, a third resistor, a fourth resistor and a trigger, wherein
the first resistor and the second resistor are coupled in series between a positive terminal and a negative terminal of the battery;
an intermediate node between the first resistor and the second resistor is coupled to control terminals of the fourth switching transistor and the fifth switching transistor,
the first switching transistor and the second switching transistor, form a matched current mirror with gates thereof coupled with each other;
the fourth switching transistor and the fifth switching transistor form a common-source amplification circuit,
the third switching transistor has a drain coupled to one terminal of the current source, and a gate coupled to a drain of the fifth switching transistor, and
the drain of the third switching transistor is coupled to an input terminal of the trigger, and an output terminal of the trigger outputs a voltage detection result.
5. The battery protection circuit according to claim 1 , further comprising:
a charging switching transistor having a first terminal coupled to a positive terminal of the battery, a second terminal coupled to a power terminal for coupling to a charging power supply, and a control terminal; and
a charging management circuit coupled with the positive terminal of the battery and the power terminal respectively, and configured to control the charging switching transistor to switch on to charge the battery when the charging power supply is coupled to the power terminal and a voltage of the charging power supply is higher than the voltage of the battery.
6. The battery protection circuit according to claim 5 , wherein the charging switching transistor is an insulated gate type of field-effect transistor.
7. The battery protection circuit according to claim 5 , further comprising:
a body selection circuit coupled with a body of the charging switching transistor and configured for selectively coupling the body of the charging switching transistor to one of the first terminal of the charging switching transistor and the second terminal of the charging transistor based on which one of the terminals has a voltage higher than the other terminal.
8. The battery protection circuit according to claim 5 , further comprising:
a high-voltage detection circuit coupled with the positive terminal of the battery and configured to detect whether the voltage of the battery is higher than a high-voltage detection threshold, and output a charging-off signal when the voltage of the battery is determined to be higher than the high-voltage detection threshold; and
a high-voltage control circuit configured to switch off the charging switching transistor to stop charging the battery when the high-voltage detection circuit outputs the charging-off signal.
9. The battery protection circuit according to claim 8 , wherein the high-voltage control circuit comprises an inverter, a second switch and a third switch, and wherein
an input terminal of the inverter is coupled with an output terminal of the high-voltage detection circuit, the second switch is coupled between an output terminal of the charging management circuit and the control terminal of the charging switching transistor, and a control terminal of the second switch is coupled with an output terminal of the inverter, and
the third switch is coupled between the control terminal of the charging switching transistor and a body of the charging switching transistor, and a control terminal of the third switch is coupled with the output terminal of the high-voltage detection circuit.
10. The battery protection circuit according to claim 1 , wherein the battery management circuit comprises at least one of a direct current to direct current converter, a voltage regulator, a power switch and a charge pump.
11. A battery protection system, comprising:
a battery;
a battery protection circuit comprising:
a power button;
a power detection circuit;
a first switch coupled between a power button and the power detection circuit, the power detection circuit configured to output a power-off signal when either the first switch or the power button is in a switch-off state;
a low-voltage detection circuit coupled with the battery and configured to detect whether a voltage of the battery is lower than a low-voltage detection threshold or not, and switch off the first switch to cut off an electric leakage path of the battery when the voltage of the battery is determined to be lower than the low-voltage detection threshold; and
a power management circuit coupled with the power detection circuit and configured to cut off an electric discharge path of the battery to prohibit the battery from discharging when receiving the power-off signal.
12. The battery protection system according to claim 11 , wherein the low-voltage detection circuit comprises a first resistor, a second resistor, a current source, a switching transistor, a trigger and an inverter; and wherein
the first resistor and the second resistor are coupled in series between a positive terminal and a negative terminal of the battery;
the switching transistor has a control terminal coupled to an intermediate node between the first resistor and the second resistor, and a collector terminal coupled with an output terminal of the current source and an input terminal of the trigger;
an input terminal of the current source is coupled with the positive terminal of the battery, an output terminal of the trigger is coupled to an input terminal of the inverter, and the inverter outputs a voltage detection result, and
the low-voltage detection threshold is determined by a ratio of a resistance value of the first resistor to a resistance value of the second resistor.
13. The battery protection system according to claim 12 , wherein the low-voltage detection circuit comprises a first resistor, a second resistor, a current source, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a fifth switching transistor, a third resistor, a fourth resistor and a trigger, and wherein
the first resistor and the second resistor are coupled in series between a positive terminal and a negative terminal of the battery;
an intermediate node between the first resistor and the second resistor is coupled to control terminals of the fourth switching transistor and the fifth switching transistor,
the first switching transistor and the second switching transistor, form a matched current mirror with gates thereof coupled with each other;
the fourth switching transistor and the fifth switching transistor form a common-source amplification circuit,
the third switching transistor has a drain coupled to one terminal of the current source, and a gate coupled to a drain of the fifth switching transistor, and
the drain of the third switching transistor is coupled to an input terminal of the trigger, and an output terminal of the trigger outputs a voltage detection result.
14. The battery protection system according to claim 11 , wherein the battery protection circuit further comprising:
a charging switching transistor having a first terminal coupled to a positive terminal of the battery, a second terminal coupled to a power terminal for coupling to a charging power supply, and a control terminal; and
a charging management circuit coupled with the positive terminal of the battery and the power terminal respectively, and configured to control the charging switching transistor to switch on to charge the battery when the charging power supply is coupled to the power terminal and a voltage of the charging power supply is higher than the voltage of the battery.
15. The battery protection system according to claim 14 , wherein the charging switching transistor is an insulated gate type of field-effect transistor.
16. The battery protection circuit according to claim 14 , wherein the battery protection circuit further comprising:
a body selection circuit coupled with a body of the charging switching transistor and configured for selectively coupling the body of the charging switching transistor to one of the first terminal of the charging switching transistor and the second terminal of the charging transistor based on which one of the terminals has a voltage higher than the other terminal.
17. The battery protection system according to claim 14 , wherein the battery protection circuit further comprising:
a high-voltage detection circuit coupled with the positive terminal of the battery and configured to detect whether the voltage of the battery is higher than a high-voltage detection threshold, and output a charging-off signal when the voltage of the battery is determined to be higher than the high-voltage detection threshold; and
a high-voltage control circuit configured to switch off the charging switching transistor to stop charging the battery when the high-voltage detection circuit outputs the charging-off signal.
18. The battery protection system according to claim 17 , wherein the high-voltage control circuit comprises an inverter, a second switch and a third switch, and wherein
an input terminal of the inverter is coupled with an output terminal of the high-voltage detection circuit, the second switch is coupled between an output terminal of the charging management circuit and the control terminal of the charging switching transistor, and a control terminal of the second switch is coupled with an output terminal of the inverter, and
the third switch is coupled between the control terminal of the charging switching transistor and a body of the charging switching transistor, and a control terminal of the third switch is coupled with the output terminal of the high-voltage detection circuit.
19. The battery proctection system according to claim 11 , wherein the power management circuit comprises at least one of a direct current to direct current converter, a voltage regulator, a power switch and a charge pump.