The UC1842/3/4/5 family is a current mode PWM controller optimized for off-line and DC to DC converters. It features low start-up current, automatic feed forward compensation, pulse-by-pulse current limiting, enhanced load response characteristics, etc.
The UC1842/3/4/5 family of control ICs provides necessary features to implement off-line or DC-to-DC fixed frequency current mode control schemes with a minimal external parts count. The device includes internally implemented circuits such as under-voltage lockout, a precision reference, logic for latched operation, and a PWM comparator that also provides current limit control.
| Operating Supply Current | 1 to 17 mA |
|---|---|
| Maximum Duty Cycle (UC1842/3) | 95 to 100 % |
| Start-Up Current | < 1 mA |
The UC1842 has a start threshold of 16V and an off threshold of 10V.
The UC1842 has a UVLO threshold of 16V to turn on and 10V to turn off.
The UC1842 can operate with duty cycles approaching 100%.