Low-dropout regulator and short-circuit recovery soft-start protection circuit

Abstract

This invention provides a low-dropout linear regulator and a short-circuit recovery soft-start protection circuit. The short-circuit recovery soft-start protection circuit is applied to the low-dropout linear regulator. The short-circuit recovery soft-start protection circuit includes a clamping circuit and a soft-start reference circuit. The clamping circuit includes a voltage difference supply circuit, an operational amplifier, and a switching element. The voltage difference supply circuit provides a voltage difference between the first input terminal of the low-dropout linear regulator and the first input terminal of the operational amplifier. The second input terminal of the operational amplifier is connected to the output terminal of the low-dropout linear regulator. The first terminal of the switching element is connected to a buffer reference node. The control terminal of the switching element is connected to the output terminal of the operational amplifier. The soft-start reference circuit charges the voltage of the buffer reference node to a reference voltage.

Claims

1. A low-dropout linear regulator, comprising: an error amplifier, a first input terminal of the error amplifier connected to a buffer reference node, an output terminal of the error amplifier connected to a feedback node, and a second input terminal of the error amplifier; and a short-circuit recovery soft-start protection circuit, comprising: a clamping circuit, comprising: an operational amplifier having a first input terminal and a second input terminal, the second input terminal of the operational amplifier connected to the feedback node; and a voltage difference providing circuit connected between the buffer reference node and the first input terminal of the operational amplifier, configured to provide a voltage difference between the buffer reference node and the first input terminal of the operational amplifier; A switching element, wherein a first terminal of the switching element is connected to the buffer reference node, a second terminal of the switching element is grounded, and a control terminal of the switching element is connected to the output terminal of the operational amplifier; And a soft-start reference circuit connected to the buffer reference node, configured to charge the voltage of the buffer reference node to an equal reference voltage.

2. The low dropout linear regulator as claimed in claim 1 further comprises: a voltage divider circuit, wherein the output of the error amplifier is connected to an output node, the voltage divider circuit is connected between the output node and the feedback node, and the voltage divider circuit is configured to divide an output voltage of the output node to output a feedback voltage to the feedback node.

3. The low dropout linear regulator as claimed in claim 1, wherein the clamping circuit further comprises: a dejitter circuit connected between the feedback node and the second input of the operational amplifier, configured to receive a feedback signal from the feedback node and transmit only waveforms of the feedback signal having a frequency exceeding a frequency threshold to the second input of the operational amplifier.

4. The low-dropout linear regulator as claimed in claim 1, wherein the soft-start reference circuit comprises: a buffer reference voltage generating circuit connected to the buffer reference node; and a charging circuit connected to the buffer reference node and the buffer reference voltage generating circuit, configured to charge the buffer reference voltage generating circuit such that the buffer reference voltage generating circuit outputs a charging voltage to the buffer reference node.

5. The low dropout linear regulator as claimed in claim 4, wherein the buffer reference voltage generation circuit comprises: a reference capacitor, a first terminal of which is connected to the charging circuit and the first input terminal of the error amplifier, and a second terminal of which is grounded.

6. The low dropout linear regulator as claimed in claim 5, wherein the buffered reference voltage generation circuit further comprises: a reference current source connected to the first terminal of the reference capacitor, configured to supply a reference input current to the reference capacitor.

7. The low-dropout linear regulator of claim 5, wherein the charging circuit comprises: a first transistor, a first terminal of the first transistor being coupled to an input voltage, and a control terminal of the first transistor being connected to the buffer reference node; a second transistor, a first terminal of the second transistor being connected to a second terminal of the first transistor; a third transistor, a first terminal of the third transistor being connected to the input voltage, and a control terminal of the third transistor being coupled to the reference voltage; a fourth transistor, a first terminal of the fourth transistor being connected to the second terminal of the third transistor, and a control terminal of the fourth transistor being connected to the control terminal of the second transistor and the first terminal; and a fifth transistor, a first terminal of the fifth transistor being connected to the first terminal of the reference capacitor, a second terminal of the fifth transistor being connected to the second terminal of the third transistor and the second terminal of the fourth transistor, and a control terminal of the fifth transistor being connected to the first terminal of the fourth transistor.

8. The low dropout linear regulator as claimed in claim 7, wherein the charging circuit further comprises: an input current source, the input terminal of the input current source being coupled to the input voltage, and the output terminal of the input current source being connected to the first terminal of the first transistor and the first terminal of the third transistor.

9. The low dropout linear regulator as claimed in claim 7, wherein the charging circuit further comprises: an input resistor, a first end of which is connected to the control terminal of the fifth transistor; and an input capacitor, a first end of which is connected to a second end of the input resistor, and a second end of which is connected to the second terminal of the fifth transistor.

10. A short-circuit recovery soft-start protection circuit, applicable to a low-dropout linear regulator, wherein a first input terminal of the low-dropout linear regulator is connected to a buffer reference node, an output terminal of the low-dropout linear regulator is connected to a feedback node and a second input terminal of the low-dropout linear regulator, the short-circuit recovery soft-start protection circuit comprising: a clamping circuit comprising: an operational amplifier having a first input terminal and a second input terminal, the second input terminal of the operational amplifier being connected to the feedback node; and a voltage difference providing circuit connected between the buffer reference node and the first input terminal of the operational amplifier, configured to provide a voltage difference between the buffer reference node and the first input terminal of the operational amplifier; A switching element, wherein a first terminal of the switching element is connected to the buffer reference node, a second terminal of the switching element is grounded, and a control terminal of the switching element is connected to the output terminal of the operational amplifier; And a soft-start reference circuit connected to the buffer reference node, configured to charge the voltage of the buffer reference node to an equal reference voltage.

11. The short-circuit recovery soft-start protection circuit as claimed in claim 10, wherein the low-dropout linear regulator includes an error amplifier, a first input of the error amplifier being connected to a buffer reference node, and an output of the error amplifier being connected to the feedback node and a second input of the error amplifier.

12. The short-circuit recovery soft-start protection circuit as claimed in claim 10, wherein the low-dropout linear regulator further comprises: a voltage divider circuit, wherein the output of the low-dropout linear regulator is connected to an output node, the voltage divider circuit is connected between the output node and the feedback node, the voltage divider circuit being configured to divide an output voltage of the output node to output a feedback voltage to the feedback node.

13. The short-circuit recovery soft-start protection circuit as claimed in claim 10, wherein the clamping circuit further comprises: a debouncing circuit connected between the feedback node and the second input of the operational amplifier, configured to receive a feedback signal from the feedback node and transmit only waveforms of the feedback signal having a frequency exceeding a frequency threshold to the second input of the operational amplifier.

14. The short-circuit recovery soft-start protection circuit as claimed in claim 10, wherein the clamping circuit further comprises: a buffer reference voltage generating circuit connected to the buffer reference node; and a charging circuit connected to the buffer reference node and the buffer reference voltage generating circuit, configured to charge the buffer reference voltage generating circuit such that the buffer reference voltage generating circuit outputs a charging voltage to the buffer reference node.

15. The short-circuit recovery soft-start protection circuit as claimed in claim 14, wherein the buffer reference voltage generating circuit comprises: a reference capacitor, a first terminal of which is connected to the charging circuit and the first input terminal of the low-dropout linear regulator, and a second terminal of which is grounded.

16. The short-circuit recovery soft-start protection circuit as claimed in claim 15, wherein the buffered reference voltage generating circuit comprises: a reference current source connected to the first terminal of the reference capacitor and configured to supply a reference input current to the reference capacitor.

17. The short-circuit recovery soft-start protection circuit as claimed in claim 16, wherein the charging circuit comprises: a first transistor, a first terminal of the first transistor being coupled to an input voltage, and a control terminal of the first transistor being connected to the buffer reference node; a second transistor, a first terminal of the second transistor being connected to a second terminal of the first transistor; a third transistor, a first terminal of the third transistor being connected to the input voltage, and a control terminal of the third transistor being coupled to the reference voltage; a fourth transistor, a first terminal of the fourth transistor being connected to the second terminal of the third transistor, and a control terminal of the fourth transistor being connected to the control terminal of the second transistor and the first terminal; and a fifth transistor, a first terminal of the fifth transistor being connected to the first terminal of the reference capacitor, a second terminal of the fifth transistor being connected to the second terminal of the third transistor and the second terminal of the fourth transistor, and a control terminal of the fifth transistor being connected to the first terminal of the fourth transistor.

18. The short-circuit recovery soft-start protection circuit as claimed in claim 17, wherein the charging circuit further comprises: an input current source, the input terminal of the input current source being coupled to the input voltage, and the output terminal of the input current source being connected to the first terminal of the first transistor and the first terminal of the third transistor.

19. The short-circuit recovery soft-start protection circuit as claimed in claim 17, wherein the charging circuit further comprises: an input resistor, a first end of which is connected to the control terminal of the fifth transistor; and an input capacitor, a first end of which is connected to a second end of the input resistor, and a second end of which is connected to the second terminal of the fifth transistor.

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