Switching power supply controller and switching power supply

Abstract

The invention discloses a controller of a switching power supply and a switching power supply, which are applied to the field of power supplies. The output end of the transconductance amplifier is connected to the first end of the first capacitor connected to the COMP pin outside the switching power supply controller, and the control module generates the switch tube according to the second voltage output by the voltage detection module or the fourth voltage output by the current detection module The control signal is used to control the switching tube, and then control the switching power supply to work in the constant voltage output mode or constant current output mode. In addition, the first capacitor makes the change of the second voltage or the fourth voltage relatively slow, which can be considered to be constant within a period of a power frequency half-wave, and then the control signal for controlling the switch tube changes relatively slowly, making the conduction of the primary coil relatively slow. The change of the pass time is slow and approximately fixed, and a higher PF (Power Factor) can be achieved. Compatible with constant voltage output mode and constant current output mode under the condition of achieving higher PF to meet the needs of more systems.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to a controller of a switching power supply and a switching power supply. Background technique [0002] PFC (Power Factor Correction, power factor modulation) achieves a higher PF (Power Factor, power factor) by fixing the on-time of the primary coil of the transformer. In the prior art, a large capacitor is often connected outside the controller of the switching power supply, and the controller adjusts the conduction time of the primary coil of the transformer according to the voltage of the pin connected to the capacitor and the controller, and the conduction time of the primary coil of the transformer is adjusted. The time is the conduction time of the switching tube of the switching power supply. The voltage of the pin changes slowly through the capacitor. In a cycle of a power frequency half-wave, the voltage of the pin can be regarded as constant, and the on-time of the primary ...

AI Technical Summary

Problems solved by technology

However, the voltage of the pin can only reflect one of the output voltage of the secondary side of the transformer or the primary current of the transformer, that is, the controller can only adjust the conduction time of the primary coil according to the output voltage or the primary current to achieve constant voltage output. A kind of control or constant current output control, not compatible with constant voltage output control and constant current output control

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