The SG1844/45 family of control ICs provides all the necessary features to implement off-line fixed frequency, currentmode 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. Oscillator discharge current is trimmed to less than 10%. The SG1844/45 has undervoltage lockout, current-limiting circuitry