General Description

The MIC38C4xA are fixed frequency, high performance, current-mode PWM controllers. Micrel’s BiCMOS devices

are pin compatible with 384x bipolar devices but feature several improvements.

Features

• Fast 40ns output rise and 30ns output fall times

• –40°C to +85°C temperature range meets UC284x specifications

• High-performance, low-power BiCMOS Process

• Ultralow start-up current (100µA typical)

• Low operating current (4mA typical)

• CMOS outputs with rail-to-rail swing

• ≥500kHz current-mode operation

•Trimmed 5V bandgap reference

• Pin-for-pin compatible with UC3842/3843/3844/3845

• Trimmed oscillator discharge current

• UVLO with hysteresis

• Low cross-conduction currents

Applications

• Current-mode, off-line, switched-mode power supplies

• Current-mode, dc-to-dc converters.

• Step-down “buck” regulators

• Step-up “boost” regulators

• Flyback, isolated regulators

• Forward converters

• Synchronous FET converters