UCC2884

The UCC3884 is a high performance current mode PWM controller intended or single ended switch mode power supplies. The chip implements  frequency foldback scheme that decreases the oscillator frequency as he output voltage falls below a programmed value. This technique decreases he average output current sourced into a low impedance load hich can occur during an output short circuit or overload condition. Excessive hort circuit current is more prevalent in high frequency converters here the propagation delay and switch turn-off time forces a minimum attainable uty cycle. An accurate volt-second clamp limits the duty cycle uring line or load transient conditions which could otherwise saturate the ransformer. The volt-second clamp may also be used with an external vervoltage protection circuit to handle fault conditions such as current ense disconnect or current transformer saturation. The frequency  oldback, volt-second clamp, cycle-by-cycle current limit, and overcurrent hutdown provide a rich set of protection features for use in peak current ode pulse width modulators.