The UCCx808A devices are a family of BiCMOS push-pull, high-speed, low-power,
pulse-width modulators. The UCCx808A contains all of the control and drive circuitry required for
off-line or DC-to-DC fixed frequency current-mode switching power supplies with minimal external
The UCCx808A dual-output drive stages are arranged in a push-pull configuration. Both
outputs switch at half the oscillator frequency using a toggle flip-flop. The dead time between the
two outputs is typically 60 ns to 200 ns depending on the values of the timing capacitor and
resistors, thus limiting each output stage duty cycle to less than 50%.
The UCCx808A family offers a variety of package options, temperature range options, and
choice of undervoltage lockout levels. The family has UVLO thresholds and hysteresis options for
off-line and battery-powered systems.
The UCCx808A is an enhanced version of the UCC3808 family. The significant difference is
that the A versions feature an internal discharge transistor from the CS pin to ground, which is
activated each clock cycle during the oscillator dead time. The feature discharges any filter
capacitance on the CS pin during each cycle and helps minimize filter capacitor values and current