UC3843BVN

Product Summary

The UC3843BVN is a high performance fixed frequency current mode controller. It is 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 undervoltage lockouts each with hysteresis, cycle–by–cycle current limiting, programmable output deadtime, and a latch for single pulse metering. This device is available in an 8–pin dual–in–line. The UC3843BVN is tailored for lower voltage applications having UVLO thresholds of 8.5 V (on) and 7.6 V (off).

Parametrics

UC3843BVN absolute maximum ratings: (1)Total Power Supply and Zener Current, (ICC + IZ): 30mA; (2)Output Current, Source or Sink, IO: 1.0A; (3)Output Energy (Capacitive Load per Cycle), W: 5.0mJ; (4)Current Sense and Voltage Feedback Inputs, Vin: -0.3 to +5.5V; (5)Error Amp Output Sink Current, IO: 10mA; (6)D Suffix, Plastic Package, SO–14 Case 751A, Maximum Power Dissipation @ TA = 25℃, PD: 862mW; (7)D Suffix, Plastic Package, SO–14 Case 751A, Thermal Resistance, Junction–to–Air, RqJAL: 145℃/W; (8)D1 Suffix, Plastic Package, SO–8 Case 751, Maximum Power Dissipation @ TA = 25℃, PD: 702mW; (9)D1 Suffix, Plastic Package, SO–8 Case 751, Thermal Resistance, Junction–to–Air, RqJA: 178℃/W; (10)N Suffix, Plastic Package, Case 626, Maximum Power Dissipation @ TA = 25℃, PD: 1.25W; (11)N Suffix, Plastic Package, Case 626, Thermal Resistance, Junction–to–Air, RqJA: 100℃/W; (12)Operating Junction Temperature, TJ: +150℃; (13)Operating Ambient Temperature, TA: –40 to +105℃; (14)Storage Temperature Range, Tstg: –65 to +150℃.

Features

UC3843BVN features: (1)Trimmed Oscillator for Precise Frequency Control; (2)Oscillator Frequency Guaranteed at 250 kHz; (3)Current Mode Operation to 500 kHz; (4)Automatic Feed Forward Compensation; (5)Latching PWM for Cycle–By–Cycle Current Limiting; (6)Internally Trimmed Reference with Undervoltage Lockout; (7)High Current Totem Pole Output; (8)Undervoltage Lockout with Hysteresis; (9)Low Startup and Operating Current.

Diagrams