AC signal detector and the method thereof

Patent metadata

Field	Value
Publication number	US-9201102-B2
Application number	US-201313931749-A
Country	US
Kind code	B2
Filing date	Jun 28, 2013
Priority date	Jul 16, 2012
Publication date	Dec 1, 2015
Grant date	Dec 1, 2015

Abstract

An AC signal detector having: a rectify circuit having a first input terminal and a second input terminal configured to receive an AC signal, and an output terminal configured to provide a rectified signal based on the AC signal; a detecting circuit having an input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal, and an output terminal configured to provide a square signal based on the rectified signal; and an unplug indicate circuit having an input terminal coupled to the detecting circuit to receive the square signal, and an output terminal configured to provide an unplug indicate signal based on the square signal.

First claim

We claim:

1. An AC signal detector, comprising:
a rectify circuit having a first input terminal and a second input terminal configured to receive an AC signal, and an output terminal configured to provide a rectified signal based on the AC signal;
a detecting circuit having an input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal, and an output terminal configured to provide a square signal based on the rectified signal; and
an unplug indicate circuit having an input terminal coupled to the detecting circuit to receive the square signal, and an output terminal configured to provide an unplug indicate signal based on the square signal.

2. The AC signal detector of claim 1 , wherein the detecting circuit comprises:
a delay circuit having an input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal and an output terminal configured to provide a delayed rectified signal based on the rectified signal; and
a detecting comparator, having a first input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal, a second input terminal coupled to the output terminal of the delay circuit to receive the delayed rectified signal, and an output terminal configured to provide the square signal based on the rectified signal and the delayed rectified signal.

3. The AC signal detector of claim 1 , wherein the unplug indicate circuit comprises:
a rising edge flip-flop having an input terminal coupled to the output terminal of the detecting circuit to receive the square signal and an output terminal configured to provide a rising edge pulse signal based on the square signal;
a falling edge flip-flop having an input terminal coupled to the output terminal of the detecting circuit to receive the square signal, and an output terminal configured to provide a falling edge pulse signal at the falling edge of the square signal;
an signal adding circuit having a first input terminal coupled to the output terminal of the rising edge flip-flop to receive the rising edge pulse signal, a second input terminal coupled to the output terminal of the falling edge flip-flop to receive the falling edge pulse signal, and an output terminal configured to provide an pulse added signal based on the rising edge pulse signal and the falling edge pulse signal; and
a counting circuit having an input terminal coupled to the output terminal of the signal adding circuit to receive the pulse added signal and an output terminal configured to provide an unplug indicate signal based on the pulse added signal;
wherein the counting circuit counts interval time between adjacent pulses of the pulse added signal, and the unplug indicate signal is invalid when the interval time between adjacent pulses of the pulse added signal is smaller than or equal to a first preset value, and is valid when the interval time between the adjacent pulses of the pulse added signal is larger than the first preset value.

4. The AC signal detector of claim 3 , wherein the counting circuit comprises:
a charging current source having a first terminal coupled to an internal power and a second terminal configured to provide a current;
a capacitor having a first terminal coupled to the second terminal of the charging current source to receive the current and a second terminal connected to a ground;
a counting switch having a first terminal coupled to the first terminal of the capacitor, a second terminal connected to the ground and a control terminal configured to receive the pulse added signal, wherein based on the pulse added signal, the counting switch is turned ON and OFF; and
a counting comparator having a first input terminal coupled to the first terminal of the capacitor, a second input terminal configured to receive a reference signal, and an output terminal configured to provide the unplug indicate signal based on a voltage across the capacitor and the reference signal.

5. The AC signal detector of claim 1 , wherein the unplug indicate circuit comprises:
a rising edge flip-flop having an input terminal coupled to the output terminal of the detecting circuit to receive the square signal and an output terminal configured to provide a rising edge pulse signal at a rising edge of the square signal; and
a counting circuit having an input terminal coupled to the output terminal of the rising edge flip-flop to receive the rising edge pulse signal, and an output terminal configured to provide an unplug indicate signal based on the rising edge pulse signal;
wherein the counting circuit counts an interval time between adjacent pulses of the rising edge pulse signal, and the unplug indicate signal is invalid when the interval time between the adjacent pulses of the rising edge pulse signal is smaller than or equal to a second preset value, and is valid when the interval time between the adjacent pulses of the rising edge pulse signal is larger than the second preset value.

6. The AC signal detector of claim 5 , wherein the counting circuit comprises:
a charging current source having a first terminal coupled to an internal power and a second terminal configured to provide a current;
a capacitor having a first terminal coupled to the second terminal of the charging current source to receive the current and a second terminal connected to a ground;
a counting switch having a first terminal coupled to the first terminal of the capacitor, a second terminal connected to the ground and a control terminal configured to receive the rising edge pulse signal, wherein based on the rising edge pulse signal, the counting switch is turned ON and OFF; and
a counting comparator having a first input terminal coupled to the first terminal of the capacitor, a second input terminal configured to receive a reference signal, and an output terminal configured to provide the unplug indicate signal based on a voltage across the capacitor and the reference signal.

7. The AC signal detector of claim 1 , wherein the unplug indicate circuit comprises:
a falling edge flip-flop having an input terminal coupled to the output terminal of the detecting circuit to receive the square signal and an output terminal configured to provide a falling edge pulse signal at a rising edge of the square signal; and
a counting circuit having an input terminal coupled to the output terminal of the falling edge flip-flop to receive the falling edge pulse signal, and an output terminal configured to provide an unplug indicate signal based on the falling edge pulse signal;
wherein the counting circuit counts interval time between adjacent pulses of the falling edge pulse signal, and the unplug indicate signal is invalid when the interval time between the adjacent pulses of the falling edge pulse signal is smaller than or equal to a second preset value, and is valid when the interval time between the adjacent pulses of the falling edge pulse signal is larger than the second preset value.

8. The AC signal detector of claim 7 , wherein the counting circuit comprises:
a charging current source having a first terminal coupled to an internal power and a second terminal configured to provide a current;
a capacitor having a first terminal coupled to the second terminal of the charging current source to receive the current and a second terminal connected to a ground;
a counting switch having a first terminal coupled to the first terminal of the capacitor, a second terminal connected to the ground and a control terminal configured to the receive the falling edge pulse signal, wherein based on the falling edge pulse signal, the counting switch is turned ON and OFF; and
a counting comparator having a first input terminal coupled to the first terminal of

Assignees

• Chengdu Monolithic Power Sys

Inventors

• Wang Siran
• Li Yike
• Yi Kun
• Ren Yuancheng
• Zhang Junming
• Li En

Classifications

• G01R19/175 Primary

  Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero · CPC title

• G01R31/42

  AC power supplies · CPC title