The MIC38C4x is a fixed frequency, high performance, current mode PWM controller. Microchip's BiCMOS device is compatible with 384x bipolar devices, but with several improvements. The undervoltage locking circuit allows' 42 and '44 versions to start at 14.5V and run as low as 9V, and' 43 and '45 versions to start at 8.4V and run as low as 7.6V.
Functional Block Diagram
All versions operate up to 20V. Compared to a bipolar 384x device operating on a 15V power supply, the starting current is reduced to a typical 50 μA and the operating current is reduced to a typical 4.0 mA. Reduced output rise and fall times drive larger MOSFeTs, and rail-to-rail output capabilities improve efficiency, especially at lower supply voltages.
The MIC38C4x also features a trimmer oscillator discharge current and band gap reference. MIC38C4x represents 8-pin plastic DIP, SOIC, and MSOP packages. MIC38C4x-1 represents a 14-pin plastic DIP and SOIC package. 8-pin devices are small in size, while 14-pin devices separate analog and power connections to improve performance and power consumption.