UC2841

Programmable, Off-Line, PWM Controller UC1841 UC2841 UC3841 FEATURES All Control, Driving, Monitoring, and Protection Functions Included DESCRIPTION The UC1841 family of PWM controllers has been designed to increase the level of versatility while retaining all of the performance features of Low-current, Off-line Start Circuit Voltage Feed Forward or Current Mode Control the earlier UC1840 devices. While still optimized for highly-efficient bootstrapped primary-side operation in forward or flyback power converters, the UC1841 is equally adept in implementing both low and high voltage input DC to DC converters. Important performance features include a Guaranteed Duty Cycle Clamp low-current starting circuit, linear feed-forward for constant volt-second operation, and compatibility with either voltage or current mode topologies. PWM Latch for Single Pulse per Period In addition to start-up and normal regulating PWM functions, these de- Pulse-by-Pulse Current Limiting Plus vices include built in protection from over-voltage, under-voltage, and Shutdown for Over-Current Fault over-current fault conditions with the option for either latch-off or automat- No Start-up or Shutdown Transients Slow Turn-on Both Initially and After Fault Shutdown Shutdown Upon Over- or Under-Voltage Sensing ic restart. While pin compatible with the UC1840 in all respects except that the polarity of the External Stop has been reversed, the UC1841 offers the following improve...