FAN7621SJ

FAN7621SJ application field and working principle

The FAN7621SJ is an AC/DC converter and offline switcher from the FAN7621 series of power management integrated circuits from Fairchild Semiconductor. It can be either directly mounted onto a PCB or placed on a heat sink, and is able to withstand voltages up to 700V. It is a highly reliable, ultra-low standby power converter with integrated features such as under voltage lockout, over voltage protection, over temperature protection and an auto restart function.

The FAN7621SJ is best suited for applications such as lighting, uninterruptible power supplies (UPS), air conditioners, automotive, domestic appliances and industrial control. Its wide range of features makes it an ideal fit for applications that require reliable and cost effective power solutions.

Working Principle

The FAN7621SJ works by combining an integrated flyback transformer and an external power MOSFET with frequency transformer control. It contains a power stage, a power-on reset circuit, an over-voltage protection circuit and an over-temperature protection circuit.

The power stage consists of the combination of an external power MOSFET and its drive circuit. The power-on reset circuit provides a low power reset signal to the drive circuit and system after startup. The over-voltage protection circuit controls the voltage of the output voltage sense pin, RVS, to limit the upper limit of the output voltage. The over-temperature protection circuit controls the die temperature of the FAN7621SJ by monitoring the temperature of the die package.

The FAN7621SJ also has an integrated active burst mode, which is used to reduce its standby power consumption. During normal operation, it operates in Pulse Width Modulation (PWM) mode. During an off period, it operates in active burst mode to reduce power consumption. The operating frequency is set by the external clock source and the maximum switching frequency is 500kHz.

Conclusion

In conclusion, the FAN7621SJ is an AC/DC converter and offline switcher with integrated features such as under voltage lockout, over voltage protection, over temperature protection and an auto restart function. Its wide range of features makes it an ideal fit for applications that require reliable and cost effective power solutions.