Product Overview UC2844B: High Performance Current Mode PWM Controller For complete documentation, see the data sheet Product Description The UC3844B, UC3845B 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 an oscillator, 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 undervoltage lockouts each with hysteresis, cycle-by-cycle current limiting, a latch for single pulse metering, and a flip-flop which blanks the output off every other oscillator cycle, allowing output deadtimes to be programmed from 50% to 70%. These devices are available in an 8-pin dual-in-line and surface mount (SO-8) plastic package as well as the 14-pin plastic surface mount (SO-14). The SO-14 package has separate power and ground pins for the totem pole output stage. The UCX844B has UVLO thresholds of 16 V (on) and 10 V (off), ideally suited for off-line converters. The UCX845B is tailored for lower voltage applications having UVLO thresholds of 8.5 V (on) and 7.6 V (off). Features • • • • • • • • • • Trimmed Oscillator for Precise Frequency Control Oscillator Frequency Guaranteed at 250 kHz Current Mode Operation to 500 kHz Output Switching Frequency Output Deadtime Adjustable from 50% to 70% Automatic Feed Forward Compensation Latching PWM for Cycle-By-Cycle Current Limiting Internally Trimmed Reference with Undervoltage Lockout High Current Totem Pole Output Undervoltage Lockout with Hysteresis Low Startup and Operating Current For more features, see the data sheet Part Electrical Specifications Product Compliance Status Topolog y Control Mode fsw Typ (kHz) StandUVLO by Mode (V) Short Circuit Protecti on Latch Soft Start VCC Max Drive (V) Cap. (mA) Packag e Type UC2844BD1R2G Pb-free Active Flyback Current Mode 52 No Yes Yes No No 30 200 / 200 SOIC-8 Active Flyback Current Mode 52 No Yes Yes No No 30 200 / 200 SOIC14 Active Flyback Current Mode 52 No Yes Yes No No 30 200 / 200 PDIP-8 Halide free UC2844BDR2G PPAP Capable Pb-free Halide free UC2844BNG Pb-free Halide free For more information please contact your local sales support at www.onsemi.com Created on: 6/30/2016