CR6842

The CR6842 is a low startup current , low cost, current mode PWM controller with Green-Power & burst-mode power-saving operation. The integrated functions such as the leading-edge blanking of the current sensing, internal slope compensation provide the users a high efficiency, low external component counts, and low cost solution for AC/DC power applications. The special Green-Power function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. And under zero-load conditions, the power supply enters burst-mode to further reduce power consumption by shutting off PWM output. When the output of power supply is short or over loaded, the FB voltage will increase ,and if the FB voltage is higher than 5.2V for longer than 56msec the PWM output will be turned off. A external NTC resistor connected from pin RT to ground can be applied to over-temperature protection. Pulse by pulse current limit ensures a constant output current even under short circuit. PWM output will be disabled as long as VDD exceeds a threshold. When internal latch circuit CR6842 is used to latch-off the controller, the latch will be reset when the power supply VDD is disabled.