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