1 Features

• Improved output driver and lower

operating/startup current from UCx84x/UCx84xA/

UCx84xAQ/TLx84x/TLx84xB families

• Optimized for off-line and DC-DC converters

• Low start-up current (< 0.5mA)

• Trimmed oscillator discharge current

• Automatic feedforward compensation

• Pulse-by-pulse current limiting

• Enhanced load response characteristics

• Undervoltage lockout with hysteresis

• Double pulse suppression

• High-current totem pole output

• Internally-trimmed bandgap reference

• Up to 500kHz operation

2 Applications

• Switch mode power supplies (SMPS)

• DC-DC converters

• Power modules

• Industrial PSU

• Battery operated PSU

3 Description

The UC284xL control device is a pin-for-pin

compatible improved version of the UC284x family.

Providing the necessary features to control currentmode

or switched-mode power supplies, this device

provides improved features: higher VCC range at 36V,

lower start-up current at 0.25mA, tighter operating

current tolerance at 15mA max, and faster response

on cycle-by-cycle current protection at 100ns. Output

driver of UC284xL is improved with shorter rise and

fall time at 75ns max to reduce switching loss, and

stronger driver capabilities with lower output low level

farther from the FETs threshold voltage.