Switching mode power supply providing an over current protection with anti-surge function
AssigneeChengdu Monolithic Power Systems Co., Ltd.
InventorsYuedong Chen, Yiqing Jin, Zhiheng Hu
Life of this patent
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Abstract
A switching mode power supply preventing false triggering of an over current protection due to a surge pulse. The switching mode power supply has a switch and an inductor. An inductor current flows through the inductor. The switching mode power supply turns off the switch and meanwhile starts timing for a preset period of time when the inductor current is larger than a preset value. The switch is kept off during the preset period of time and is then turned on when the preset period of time expires.
Claims17
A driving circuit in a switching mode power supply, wherein the switching mode power supply comprises an inductor and a switch, and wherein an inductor current flows through the inductor, the driving circuit comprising:
- an over current comparison circuit configured to receive an over current threshold signal and a first current detecting signal representative of the inductor current generated during a period when the switch is on, wherein the over current comparison circuit is configured to generate an over current comparison signal to control a turning-off moment of the switch based on comparing the first current detecting signal with the over current threshold signal;
- a watch-dog circuit configured to receive a watch-dog triggering signal indicating the turning-off moment of the switch, wherein the watch-dog circuit is configured to generate a watch-dog signal based on the watch-dog triggering signal to trigger a turning-on operation of the switch after a preset period of time expires, and wherein the preset period of time is timed beginning from the turning-off moment of the switch;
- an on moment control circuit configured to receive a second current detecting signal representative of the inductor current generated during a period when the switch is off and to receive an on threshold signal, wherein the on moment control circuit is configured to generate an on signal to control a turning-on moment of the switch based on comparing the second current detecting signal with the on threshold signal, and wherein the on moment control circuit is enabled or disable by the over current comparison signal;
- and
- a switching control circuit configured to generate a switching control signal based on the over current comparison signal, the watch-dog signal and the on signal to control the turning-on moment and the turning-off moment of the switch.
A switching mode power supply, comprising:
- an inductor, wherein an inductor current flows through the inductor;
- a switch;
- and
- a driving circuit, comprising:
- an over current comparison circuit configured to receive an over current threshold signal and a first current detecting signal representative of the inductor current generated during a period when the switch is on, wherein the over current comparison circuit is configured to generate an over current comparison signal to control a turning-off moment of the switch based on comparing the first current detecting signal with the over current threshold signal;
- a watch-dog circuit configured to receive a watch-dog triggering signal indicating the turning-off moment of the switch, wherein the watch-dog circuit is configured to generate a watch-dog signal based on the watch-dog triggering signal to trigger a turning-on operation of the switch after a preset period of time expires, and wherein the preset period of time is timed beginning from the turning-off moment of the switch;
- an on moment control circuit configured to receive a second current detecting signal representative of the inductor current generated during a period when the switch is off and to receive an on threshold signal, wherein the on moment control circuit is configured to generate an on signal to control a turning-on moment of the switch based on comparing the second current detecting signal with the on threshold signal, and wherein the on moment control circuit is enabled or disable by the over current comparison signal;
- and
- a switching control circuit configured to generate a switching control signal based on the over current comparison signal, the watch-dog signal and the on signal to control the turning-on moment and the turning-off moment of the switch.
Dependencies are inferred from the claim text.