The SG3842/43 family of control ICs provides all the necessary features to implement off-line fixed frequency, current-mode switching power supplies with a minimum number of external components. Current-mode architecture demonstrates improved line regulation, improved load regulation, pulse-by-pulse current limiting, and inherent protection of the power supply output switch. The bandgap reference is trimmed to ±1% over temperature. The oscillator discharge current is trimmed to less than ±10%. The SG3842/43 has an under-voltage lockout, current limiting circuitry, and a start-up current of less than 1mA. The totem-pole output is optimized to drive the gate of a power MOSFET. The output is low in the off state to provide a direct interface to an N-channel device.
