Drain-source voltage detection circuit and drain-source voltage detection method

Abstract

The invention relates to the field of voltage detection, and discloses a drain-source voltage detection circuit and a drain-source voltage detection method. The detection circuit comprises a clamping circuit and a first controller. The clamping circuit is electrically connected with a gate electrode of a main switch tube, and the first controller is electrically connected with the clamping circuit. When the main switch tube is turned off, the clamping circuit limits the gate voltage of the main switch tube within a positive clamping voltage or a negative clamping voltage, wherein the positive clamping voltage is smaller than the conduction threshold voltage of the main switch tube. Therefore, the drain-source voltage of the main switch tube is directly coupled to the clamping circuit through a gate-drain capacitor to form a first coupling signal, and the first controller detects the drain voltage of the main switch tube according to the first coupling signal. The detection circuit does not need to be additionally provided with an external assembly for sensing the drain voltage, so that noise coupling can be reduced, the detection accuracy is improved, the circuit structure is simplified, and the circuit cost is reduced.

Description

technical field [0001] The invention relates to the field of voltage detection, in particular to a drain-source voltage detection circuit and a drain-source voltage detection method. Background technique [0002] In various converters, soft switching technology is generally used to control the turn-on and turn-off of the main switch, that is, it is necessary to detect when the inductor current becomes zero, so that another energy transmission cycle can start, and the inductor and the main switch drain The capacitors on the electrodes form a resonance together, and it is necessary to detect the bottom of the resonance, so as to control the conduction of the main switch when the drain voltage reaches the bottom of the resonance waveform, so as to maximize the efficiency. [0003] Generally, a drain-source voltage detection circuit is used to detect when the inductor current and the drain voltage reach the bottom of the resonance valley, but in the current traditional drain-sou...

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Problems solved by technology

[0003] Generally, a drain-source voltage detection circuit is used to detect when the inductor current and the drain voltage reach the bottom of the resonance valley, but in the current traditional drain-source voltage detection technology, a resistor divider or a capacitor or an auxiliary winding is generally used to sense the voltage of the main switch tube. Drain voltage, but the traditional drain-source voltage detection technology needs to add external components to realize the detection of the drain voltage of the main switching tube. Since the sensing needs to be carried out in a noisy PCB environment, the external components may be in the normal switching time. It is easy to generate noise coupling with other traces, thereby reducing the accuracy of detection, and adding additional external components will make the entire circuit structure complicated and the circuit cost increased

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