深圳市尚想信息技术有限公司

The UC3844B, UC3845B series are high performance fixed frequency
current mode controllers. They are specifically designed for Off−Line
and dc−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 (SOIC−8) plastic package as well as the 14−pin plastic surface
mount (SOIC−14). The SOIC−14 package has separate power and
ground pins for the totem pole output stage.
The UCX844B has UVLO thresholds of 16V (on) and 10V (off), ideally
suited for off−line converters. The UCX845B is tailored for lower voltage
applications having UVLO thresholds of 8.5V (on) and 7.6V (off).