Leading edge blanking circuit

Abstract

According to a leading edge blanking circuit, an input signal processing module is used for acquiring and processing a first input signal to obtain a first control signal which is higher than the first input signal in voltage value and changes along with the first input signal; the potential of each node is determined by using bias current and a triode current mirror, and a steady-state point is provided for the whole circuit; the first control signal controls the conduction of a third PNP type triode so as to control the conduction of a third NPN type triode, and an RC network is combined to realize time delay so as to obtain a second control signal; meanwhile, a logic processing module is used for carrying out logic processing on the second input signal and the second control signal to generate a leading edge blanking circuit output signal, only when the second input signal is in the first state and the second control signal is in the low level, an effective leading edge blanking circuit output signal is generated, and otherwise, an invalid leading edge blanking circuit output signal is generated. The circuit is applied to a primary side feedback flyback converter, and the effects of accurately controlling primary side current sampling enabling and shielding oscillation waveforms can be achieved.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits and relates to a leading edge blanking circuit. Background technique [0002] When the primary-side feedback flyback converter is turned on, due to the influence of parasitic parameters such as leakage inductance and parasitic capacitance, usually at the moment when the power switch is turned on, the current of the power switch rises from 0 in the early stage, and there will be a current peak oscillation, the current sampling resistor R used to sample the primary current in the primary feedback flyback converter SENSE Both ends will also synchronously generate voltage spike oscillations, resulting in current sampling errors. [0003] In addition, in a switching cycle, the energy stored in the equivalent leakage inductance of the primary side of the transformer in the primary side feedback flyback converter also increases with the rise of the primary side current. When the power switch...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem of complex structure and high cost of the traditional frontier blanking circuit, and in order to solve the problem that in the primary side flyback converter, the primary side current waveform oscillates when the power switch tube is turned on, which leads to the problem of sampling error of the primary side current, the present invention A leading edge blanking circuit is proposed, the main structure is realized by a triode, and a simple digital circuit is used for logic control, which reduces the cost and complexity of circuit design

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