Flyback power supply circuit and its primary side control circuit and method

Abstract

A flyback power converter circuit and a primary side controller circuit and a method thereof are disclosed. The flyback power converter circuit includes a transformer, a power switch, a primary side controller circuit, and a secondary side controller circuit. The transformer converts an input voltage to a first, a second and a third output voltages. The primary side controller circuit and the secondary side control are powered by the second voltage and a third voltage, respectively. In a burst mode, when the second output voltage is lower than a first threshold, a power regulation mode is triggered to control the power switch, such that the second output voltage is between the first threshold and a second threshold. After a predetermined delay time period, the power regulation mode stops and the flyback power converter circuit enters a reboot procedure, wherein the power switch is OFF such that the third voltage is lower than a secondary side reboot threshold, whereby the secondary side controller circuit is reboot.

Description

technical field [0001] The invention relates to a flyback power supply circuit, in particular to a flyback power supply circuit with a power regulation mode. The present invention also relates to a primary-side control circuit and method used in a flyback power supply circuit. Background technique [0002] figure 1 A prior art flyback power supply circuit (flyback power supply circuit 1) is shown, wherein the flyback power supply circuit 1 includes a transformer 10, a power switch N1, a primary side control circuit 30 and a secondary side control circuit 20. Please also see figure 2 , figure 2 show corresponding to figure 1 The operating waveform schematic diagram of the flyback power supply circuit 1 is in a burst mode (burst mode), when the output voltage VDD1 (used as the power supply of the primary side control circuit 30) is lower than the first voltage threshold VTH1, the primary side The control circuit 30 is triggered to enter a power regulation mode to contr...

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Problems solved by technology

[0003] figure 1 and figure 2 The disadvantage of the prior art shown in , is that since the above-mentioned power regulation mode will continue continuously, when the secondary side control circuit 20 triggers, for example but not limited to, the protection mode, and the secondary side control circuit 20 is to be restarted , because VDD1 is controlled by the above-mentioned power regulation mode, the switching of the power switch N1 cannot be stopped by controlling the coupling element 40 to pull down the feedback compensation signal COMP, so VDD2 (used as the power supply of the secondary side control circuit 20) may stay at figure 2 The voltage level VHP shown in (in some cases may be higher than the restart voltage threshold VPR2 of the secondary side control circuit 20), so that the secondary side control circuit 20 cannot be restarted, the above situation may occur especially in some output The level of the voltage VOUT, so in the situation where the output voltage VOUT is variable (such as but not limited to the VBUS voltage of the USB PD specification), it is particularly easy to encounter the above-mentioned problems

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