Power switch circuit having adaptive limit current protection

Abstract

This invention discloses a power switch circuit with adaptive current limiting protection. The power switch circuit includes a power switch and a current limiting circuit. A first terminal of the power switch is coupled to a second terminal of a sensing resistor, and the first terminal of the sensing resistor is coupled to an input voltage. The second terminal of the power switch is coupled to an output voltage. The current limiting circuit is coupled to the input voltage and connected to the first terminal, the second terminal, and a control terminal of the power switch. Based on the input voltage, the voltage at the first terminal of the power switch, and the voltage at the second terminal of the power switch, the current limiting circuit sets the current limiting delay time and the current limiting value of the power switch, and controls the current limiting turn-off time of the control terminal of the power switch based on the current limiting delay time.

Claims

1. A power switch circuit with adaptive current limiting protection, comprising: a power switch, a first terminal of the power switch coupled to an input voltage, a second terminal of the power switch coupled to an output voltage, a control terminal of the power switch coupled to a charging voltage, wherein the voltage at the second terminal of the power switch is used as the output voltage of the power switch circuit with adaptive current limiting protection. A current-limiting circuit, coupled to the input voltage and connected to the first terminal, the second terminal, and the control terminal of the power switch, is configured to: multiply the input voltage by a preset ratio to obtain a voltage value, compare it with the output voltage to generate a comparison signal; obtain the corresponding reference voltage from a plurality of reference voltages based on the comparison signal; and determine whether to start current limiting based on the obtained reference voltage and the voltage at the first terminal of the power switch. A clock signal is generated based on the input voltage; a count is performed based on the comparison signal and the clock signal to generate a count value; a current-limiting delay time is set based on the count value to perform the current limiting; and a current-limiting turn-off time point is controlled based on the current-limiting delay time to perform the current limiting on the control terminal of the power switch.

2. The adaptive current limiting protection power switch circuit as claimed in claim 1, wherein the current limiting circuit comprises: a current limiting reference voltage selection circuit coupled to the input voltage and connected to the second terminal of the power switch, configured to generate the comparison signal and thereby obtain a corresponding output from a plurality of the reference voltages; a current limiting protection circuit connected to the current limiting reference voltage selection circuit, configured to determine whether to initiate current limiting based on the voltage at the first terminal of the power switch and the received reference voltage, thereby outputting a counting indication signal; and a current limiting delay time control circuit coupled to the input voltage and connected to the current limiting reference voltage selection circuit and the current limiting protection circuit, configured to: generate the clock signal based on the input voltage; count based on the comparison signal, the clock signal, and the counting indication signal to generate the count value; set a current limiting delay time for performing the current limiting based on the count value; and control the current limiting off-time point for performing the current limiting at the control terminal of the power switch based on the current limiting delay time.

3. The adaptive current limiting protection power switch circuit as claimed in claim 2, wherein the current limiting protection circuit comprises: a current limiting control circuit connected to the current limiting reference voltage selection circuit and the control terminal of the power switch, configured to control whether to start current limiting based on the voltage at the first terminal of the power switch and the received reference voltage.

4. The adaptive current limiting protection power switch circuit as claimed in claim 3, wherein the current limiting control circuit comprises: an operational amplifier, a first input terminal of the operational amplifier being connected to the current limiting reference voltage selection circuit, a second input terminal of the operational amplifier being connected to the first terminal of the power switch; and a current limiting switch, a control terminal of the current limiting switch being connected to the output terminal of the operational amplifier, a first terminal of the current limiting switch being connected to the control terminal of the power switch, and a second terminal of the current limiting switch being grounded.

5. The adaptive current limiting protection power switch circuit as claimed in claim 3, wherein the current limiting protection circuit further comprises: a current limiting start circuit connected to the current limiting control circuit and the current limiting delay time control circuit, configured to limit current according to the current limiting control circuit and output the counting indication signal; wherein the current limiting delay time control circuit is configured to generate the count value according to the counting indication signal.

6. The adaptive current limiting protection power switch circuit as claimed in claim 5, wherein the current limiting start circuit comprises: a boost resistor, a first terminal of which is coupled to a power supply voltage; a start switch, the control terminal of which is connected to the output terminal of the current limiting control circuit, the first terminal of which is connected to a second terminal of the boost resistor, and the second terminal of which is grounded; and an inverter, the input terminal of which is connected to a node between the second terminal of the boost resistor and the first terminal of the start switch, the output terminal of which outputs the counting indication signal to the connected current limiting delay time control circuit.

7. The adaptive current limiting protection power switch circuit as claimed in claim 2, wherein the current limiting reference voltage selection circuit comprises: a selection comparator circuit coupled to the input voltage and the output voltage, configured to compare the input voltage with the output voltage to output the comparison signal; and a reference voltage selection circuit connected to the selection comparator circuit, configured to select a corresponding one from a plurality of the reference voltages based on the comparison signal and output it to the current limiting protection circuit.

8. The adaptive current limiting protection power switch circuit as claimed in claim 7, wherein the selection comparator circuit comprises: a plurality of proportional circuits coupled to the input voltage and configured to multiply the input voltage by a plurality of sub-preset ratios to output a plurality of input comparison voltages, wherein the preset ratios include a plurality of the sub-preset ratios; and a plurality of comparators, each corresponding to a plurality of the proportional circuits, wherein a first input terminal of each comparator is connected to a second terminal of the power switch, a second input terminal of each comparator is connected to a corresponding proportional circuit to receive the input comparison voltage, and an output terminal of each comparator outputs the comparison signal to the connected reference voltage selection circuit.

9. The power switch circuit with adaptive current limiting protection as claimed in claim 7, wherein the reference voltage selection circuit comprises: a reference voltage generation circuit configured to output a plurality of different reference voltages; and a selection circuit connected to the reference voltage generation circuit and the selection comparison circuit, configured to select, based on the comparison signal, the corresponding one from the plurality of reference voltages and output it to the current limiting protection circuit.

10. The adaptive current limiting protection power switch circuit of claim 2, wherein the current limiting delay time control circuit comprises: a voltage-to-current conversion circuit coupled to the input voltage and configured to convert the input voltage into a ratio current; a delay switch, a first terminal of the delay switch being connected to the control terminal of the power switch and a second terminal of the delay switch being grounded; and a time control circuit connected to the voltage-to-current conversion circuit, the current limiting protection circuit, the current limiting reference voltage selection circuit and the control terminal of the delay switch, configured to output a reset signal to the delay switch based on the count indication signal, the ratio current and the comparison signal.

11. The adaptive current limiting protection power switch circuit of claim 10, wherein the time control circuit comprises: a clock generation circuit connected to the voltage-to-current conversion circuit, configured to output the clock signal based on the ratio current; a current limiting delay time counting circuit connected to the clock generation circuit, the current limiting protection circuit, and the current limiting reference voltage selection circuit, configured to output the count value based on the comparison signal, the clock signal, and the count indication signal, and to set the current limiting delay time based on the count value to output a timeout signal; and a reset counting circuit connected to the current limiting delay time counting circuit, configured to output the reset signal to the control terminal of the delay switch and the current limiting delay time counting circuit based on the timeout signal and a preset time; wherein the current limiting delay time counting circuit is configured to reset the timeout signal based on the reset signal.

12. The adaptive current limiting protection power switch circuit as claimed in claim 1 further comprises: a charging circuit connected to the control terminal of the power switch, configured to supply the charging voltage to the control terminal of the power switch.

13. The adaptive current limiting protection power switch circuit as described in claim 12 further includes: a soft-start control circuit connected to the control terminal of the power switch, configured to control the charging circuit to gradually increase the charging voltage to the control terminal of the power switch.

14. The adaptive current limiting protection power switch circuit as claimed in claim 12 further comprises: an oscillation circuit connected to the charging circuit and configured to output an oscillation signal to the charging circuit, the charging circuit supplying the charging voltage to the control terminal of the power switch according to the frequency of the oscillation signal.

15. The adaptive current limiting protection power switch circuit as claimed in claim 1 further comprises: an over-temperature protection circuit connected to the control terminal of the power switch, configured to detect the temperature of the power switch and shut down the power switch when the temperature exceeds a temperature threshold value.

16. The power switch circuit with adaptive current limiting protection as claimed in claim 1 further comprises: a sensing resistor, a first terminal of which is coupled to the input voltage, and a second terminal of which is connected to the first terminal of the power switch.

17. The power switch circuit with adaptive current limiting protection as claimed in claim 1 further comprises: an output capacitor connected between the second terminal of the power switch and ground.

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