UC3845BNG 8 Pin PWM IC

UC3845BNG Current Mode PWM Controller 8-Pin SOIC/SOT-8 Package

The UC3845BNG is a fixed-frequency, current-mode PWM controller optimized for offline and DC/DC converter designs. Operating at up to 500 kHz, it includes an internally trimmed voltage reference, undervoltage lockout with hysteresis, totem-pole output capable of driving external MOSFETs, and cycle-by-cycle current limiting.

Capable of driving peak current pulses up to ±1 A from its totem-pole output and sourcing up to 200 mA, the UC3845BNG has a UVLO threshold of 8.4 V (turn-on) and 7.6 V (turn-off), ensuring stable startup behavior. With a startup current under 1 mA, it is suitable for low-loss front-end power supplies.

Featuring automatic feed-forward compensation, latched PWM operation via flip-flop toggling for a 50% max duty cycle, and precision internal oscillator and error amplifier, this IC supports precise control in boost, flyback, forward, and buck converter topologies. The UC3845BNG operates reliably between 0 to 70 °C and complies with ROHS standards.

Key Specs Operating Frequency: Up to 500 kHz Control Mode: Current-Mode PWM UVLO Thresholds: 8.4 V (on) / 7.6 V (off) Reference Voltage: Internally trimmed 5 V Startup Current: \< 1 mA Output Drive: Totem-pole ±1 A peak / ~200 mA avg Duty Cycle Limit: 50% (via internal flip-flop) Protection: Pulse-by-pulse current limit, UVLO with hysteresis Package: 8‑pin SOIC, SOT‑8 Operating Temperature: 0 °C to 70 °C Compliance: RoHS Compliant