Flyback power converter device and its constant current controller

Abstract

The invention provides a flyback power converter device and a constant current controller thereof. The constant current controller includes a demagnetization time detection module which is configured to detect the demagnetization time TR of a secondary coil after a switch tube is switched off, a primary coil current detection module which is configured to detect a voltage rise time TF when voltage at two ends of a sampling resistor rises to preset voltage after the switch tube is switched on, a switch-on time calculation module which calculates switch switch-on time of a next switching period according to the demagnetization time TR and the voltage rise time TF of a current switching period, and a pulse width modulation signal generating module which generates pulse width modulation signals according to the switch switch-on time of the next switching period and the duration of the switching period so as to control the switching on / switching off of the switch tube. With the flyback power converter device and the constant current controller thereof adopted, cost reduction can be benefitted, and control accuracy can be improved.

Description

technical field [0001] The invention relates to a flyback power converter device and a constant current controller thereof. Background technique [0002] Flyback power converters are widely used in household appliances, battery chargers, and other products. The research direction of the flyback power converter is focused on smaller size, lower cost, stable and accurate output, and the digital power supply can just solve the above problems, and it has many characteristics that the analog power supply does not have. Some passive components are removed from the digital power supply, thereby eliminating component tolerance and aging problems; at the same time, using data to calculate the control response in the digital domain makes the control faster and more accurate, and improves the stability of the switching power supply , reliability, controllability and anti-interference. Therefore, digital power is one of the mainstream development trends of high-performance power manag...

AI Technical Summary

Problems solved by technology

[0006] but, figure 2 The circuit shown has obvious deficiencies

First, it is necessary to accurately detect the moment when the secondary coil current is zero, that is, the knee point (knee) on the curve of the feedback voltage, and it is difficult to accurately determine this moment; second, a digital-to-analog converter (DAC) is required , the cost and area of ​​the chip are relatively large; third, the PWM waveform is obtained by comparing the peak current, and there are glitches on the peak current, and a leading edge blanking circuit needs to be added, which increases the area and cost of the peripheral circuit of the chip

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