The BiCMOS design allows operation at high frequencies that were not feasible in the predecessor bipolar devices. First, the output stage has been redesigned to drive the external power switch in approximately half the time of the earlier devices. Second, the internal oscillator is more robust, with less variation as frequency increases. This faster oscillator makes this device suitable for high speed applications and the trimmed discharge current enables precise programming of the maximum duty cycle and dead-time limit. In addition, the current sense to output delay is kept the same 45 ns (typical) as the UCC28C4x-Q1. Such a delay time in the current sense results in superior overload protection at the power switch. The reduced start-up current of this device minimizes steady state power dissipation in the startup resistor, and the low operating current maximizes efficiency while running, increasing the total circuit efficiency, whether operating off-line, DC input, or battery operated circuits. These features combine to provide a device capable of reliable, high-frequency operation.