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US 2026/0213650 A1Published application
Totem pole pfc circuit with emi reduction
AssigneeChengdu Monolithic Power Systems Co., Ltd.
InventorsGuangzhuo Li, Youtu Lin, Jicheng Wang
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Abstract
A control circuit for a totem pole PFC circuit. The totem pole PFC circuit has a first half-bridge and a second half-bridge both coupled between an output terminal and a reference ground and converts an AC input voltage to an output voltage. The control circuit turns on a first switch or a second switch of the first half-bridge multiple times during a zero-crossing interval of the AC input voltage to gradually charge or discharge a switch node of the second half bridge.
Claims20
A control circuit for a totem pole PFC (power factor correction) circuit, the control circuit comprising:
- an input voltage sampling terminal configured to receive a sampling signal indicative of an AC (alternating current) input voltage of the totem pole PFC circuit;
- a zero-crossing detection circuit configured to determine whether the AC input voltage is in a zero-crossing interval based on the sampling signal and configured to generate a zero-crossing indication signal to indicate whether the AC input voltage crosses zero;
- a control signal generator configured to receive the zero-crossing indication signal and configured to generate a first control signal;
- and
- a first drive output terminal configured to provide the first control signal to a first switch of the totem pole PFC circuit;
- wherein
- during a first time period after the AC input voltage crosses zero, the first control signal is configured to turn on the first switch multiple times with a first on time;
- and wherein
- during a second time period after the AC input voltage crosses zero, the first control signal is configured to turn on the first switch multiple times with a second on time, wherein the second time period is after the first time period, and the second on time is longer than the first on time.
6 more elements
A control circuit for a totem pole PFC circuit, the control circuit comprising:
- an input voltage sampling terminal configured to receive a sampling signal indicative of an AC input voltage of the totem pole PFC circuit;
- a zero-crossing detection circuit configured to determine whether the AC input voltage is in a zero-crossing interval based on the sampling signal and configured to generate a zero-crossing indication signal to indicate whether the AC input voltage crosses zero;
- a control signal generator configured to receive the zero-crossing indication signal and configured to generate a first control signal;
- and
- a first drive output terminal configured to provide the first control signal to a first switch of the totem pole PFC circuit;
- wherein
- during a first time period after the AC input voltage crosses zero, the first control signal is configured to turn on the first switch multiple times with a first switching frequency;
- and wherein
- during a second time period after the AC input voltage crosses zero, the first control signal is configured to turn on the first switch multiple times with a second switching frequency, wherein the second time period is after the first time period, and the second switching frequency is lower than the first switching frequency.
6 more elements
A totem pole PFC circuit, comprising:
- a first half-bridge and a second half-bridge both coupled between an output terminal and a reference ground, wherein the first half-bridge includes a first switch and a second switch, and the second half-bridge includes a third switch and a fourth switch;
- an inductor coupled between a switch node of the first half-bridge and a first input terminal of the totem pole PFC circuit;
- a zero-crossing detection circuit configured to determine whether an AC input voltage of the totem pole PFC circuit is in a zero-crossing interval based on a sampling signal indicative of the AC input voltage and configured to generate a zero-crossing indication signal to indicate whether the AC input voltage crosses zero;
- and
- a control signal generator configured to receive the zero-crossing indication signal and configured to generate a first control signal and a second control signal to control the first switch and the second switch respectively;
- wherein
- during a first time period after the AC input voltage crosses zero, the first control signal is configured to turn on the first switch multiple times with a first on time;
- and wherein
- during a second time period after the AC input voltage crosses zero, the first control signal is configured to turn on the first switch multiple times with a second on time, wherein the second time period is after the first time period, and the second on time is longer than the first on time.
6 more elements
Dependencies are inferred from the claim text.