The MIC38C4x are fixed frequency, high performance, current-mode PWM controllers. Micrel’s BiCMOS devices are pin compatible with 384x bipolar devices but feature several improvements. Undervoltage lockout circuitry allows 43 versions start at 8.4V with operation down to 7.6V. All versions operate up to 20V. When compared to bipolar 384x devices operating from a 15V supply, start-up current has been reduced to 50µA typical and operating current has been reduced to 4.0 mA typical. Decreased output rise and fall times drive larger MOSFETs, and rail-to-rail output capability increases efficiency, especially at lower supply voltages. The MIC38C4x also features a trimmed oscillator discharge current and bandgap reference. The MIC38C4x denotes 8-pin plastic DIP, SOIC, and MSOP packages. 8-pin devices feature small size, while 14- pin devices separate the analog and power connections for improved perfomance and power dissipation.Fast 40ns output rise and 30ns output fall times -40°C to +85°C temperature range High-performance, low-power BiCMOS Process Ultralow start-up current (50µA typical) Low operating current (4mA typical) CMOS outputs with rail-to-rail swing = 500kHz current-mode operation Trimmed 5V bandgap reference Trimmed oscillator discharge current UVLO with hysteresis Low cross-conduction currents