Flyback PWM controller at 100 kHz
The Texas Instruments UC2572DTR is a current-mode PWM controller built for flyback topologies, switching at 100 kHz fixed frequency. It drives an external transistor in a negative output configuration — the regulation loop references the output below ground, which suits isolated flyback supplies where the secondary side floats relative to the primary return. Supply range spans 4.75 V to 30 V on Vcc/Vdd, and the internal oscillator hits a 92 % maximum duty cycle before cycle-skipping. The controller includes current-limit sensing and a ramp-compensation pin for slope compensation — both needed to prevent subharmonic oscillation when the duty cycle exceeds 50 % in continuous-conduction mode.
Housed in an 8-pin SOIC with 0.154-inch body width and 3.90 mm pitch — the standard narrow SO-8 footprint that places without tombstoning risk on a 0.062-inch board. Tape & Reel packaging (also available as Cut Tape) feeds straight into a pick-and-place machine with no special handling. No synchronous rectification on die, so the secondary-side rectifier is external; the controller drives a single transistor on the primary side.