Description

The UC3842B/43B series are high performance fixed frequency current mode controllers. They are specifically designed for Off-Line and DC-to-DC converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET.

Also included are protective features consisting of input and reference under voltage lockouts each with hysteresis, cycle-by-cycle current limiting, programmable output dead time, and a latch for single pulse metering.

These devices are available in 8-pin dual-in-line ceramic and plastic packages as well as the 8-pin plastic surface mount (SO-8). And 14-pin plastic surface mount (SO-14). SO-14 package Figure Teng column output stage has a separate power and ground pins.

Difference between members of this series is the under-voltage lockout thresholds. The UC3842B has UVLO thresholds of 16 V (on) and 10 V (off), ideally suited for off-line converters. The corresponding thresholds for the UC3843B are 8.5 V and 7.9 V.

Feature

• Trimmed Oscillator Discharge Current for Precise Duty Cycle Control

• Current Mode Operation to 500 kHz

• Automatic Feed Forward Compensation

• Latching PWM for Cycle-By-Cycle Current Limiting

• Internally Trimmed Reference with Under voltage Lockout

• High Current Totem Pole Output

• Under voltage Lockout with hysteresis

• Low Start-Up and Operating Current