Uc3842 Power Supply Circuit Diagram. Normally whenever the power fet shorted chances are very high that the uc3842 pulse width modulation pwm ic may shorted too. Figure 6 shows supply current requirements.
The uvlo circuit insures that vcc is adequate to make the uc3842 3 4 5 fully operational before enabling the output stage. U 100a uc3842 3 4 5 provides low cost current mode. After uc3842 stops working the potential of pin 1 disappears and tl431 does not turn on.
Figure 6 shows supply current requirements.
The 6 v hysteresis prevents vcc oscillations during power sequencing. I created this switching power supply for analogue semiconductor oscilloscope. Feedback to control voltage is taken from the auxiliary winding. Figure 6 shows supply current requirements.
