Switching Power Supply Voltage Detection And Control

Nowadays, the markets of the electronic mobile device are increasing, so the switching power plays an increasingly important role in the daily life of human beings, so the research of the switching power control IC(integrated circuit) are very importance.Based on 700V BCD process, this paper has designed the control chip of a flyback pulse skip modulation of the AC/DC switching power. The chip integrated a high-voltage LDMOS devices and SENSOR FET, and low-voltage transistor, low voltage MOSFET and the resistance and capacitance. The chip contains a band gap voltage reference, over-voltage under-voltage comparator, oscillator, enable / line under-voltage detection and so on, to control the status of the high voltage switching device.In the designing of the chip, this paper has studied the voltage detection and control methods of the switching power. The bypass / multi-function (BP / M) pin of the chip connected an external capacitor to provide energy to the internal control circuitry. In order to control the circuit chip to work normally, the chip detected and controled the pin voltage, this paper design a resistor divider, and then compared with the reference voltage, and then generated digital control signals to decide a capacitor charging or discharge, since controled the chip supply voltage. Oscillator generated a clock signal of 132KHz, by the frequency jitter to reduce the cost of EMI filter design, when the rising edge of every clock cycle, detected the voltage of enable / line under-voltage pin to generate control signals ,and controled the status of the power transistor in the cycle, and tested whether the chip input DC voltage line under-voltage was occurred.Based on the software HSPICE, simulated the circuit. The results show that the modules worked correctly. And then designed the module and the whole circuit layout .After all measured modules and chips.