PFC output slow start circuit and PFC output slow start time sequence control method

Abstract

The invention relates to a PFC output slow start circuit and a PFC output slow start time sequence control method, the circuit comprises a PFC module and a delay control module, the PFC module comprises a pre-start voltage output end, a power voltage positive phase output end, a power voltage negative phase output end and a loadable signal output end; the pre-starting voltage output end is connected to the power voltage negative phase output end through the surge suppression resistor and the energy storage capacitor in sequence, the power voltage positive phase output end is connected to the power voltage negative phase output end through the energy storage capacitor, and the delay control module is connected to the loadable signal output end; the power voltage normal phase output end is sequentially connected with a slow-start resistor and a slow-start switch. The end, away from the slow-start switch, of the slow-start resistor is connected with the end, away from the slow-start resistor, of the slow-start switch through a short-circuit switch. The power voltage negative phase output end is connected to the slow start switch through the slow start capacitor. The method has the advantage that the limitation of the driving capability of the loadable signal is relieved.

Description

technical field [0001] The present application relates to the field of power control, in particular to a PFC output slow start circuit and a PFC output slow start sequence control method. Background technique [0002] For most switching power supply devices that use commercial power as the input power supply, after rectifying and smoothing the commercial power to convert it into a DC voltage, a DC-DC converter is required to switch it, so the input current tends to become discontinuous and deviate from the sine wave. In order to prevent failures caused by the resulting harmonic currents, it is necessary to perform harmonic current limiting that classifies power supplies for electronic equipment according to applications, input power, and the like. [0003] In order to create this restriction, a circuit called a PFC (Power Factor Improvement Circuit) converter is added to a power supply of an electronic device to suppress harmonic current. Such as figure 1 as shown, figur...

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Problems solved by technology

Since the PFC module has its own surge suppression function, if it is started with load, the surge suppression part will be burned, so the subsequent DC / DC module needs to receive the loadable signal given by the loadable signal output terminal of the PFC. (that is, the external load EN signal) can start the output load

[0004] However, in actual use, it is found that the DC / DC module of the rear stage needs to receive the loadable signal of the PFC module before it can be turned on, and the front and rear module connection lines are added. When using, it is also necessary to increase the control circuit of the post-stage module

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