SG1844 Datasheet | Microsemi

SG1844/SG1845/SG3844/SG3845 Current Mode PWM Controller Description The SG1844/45 family of control ICs provides all the required Features to implement off-line Fixed Frequency, Current-mode switching power supplies with a minimum number of external ponents. 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 under-voltage lockout, current-limiting circuitry and start-up current of less than 1m A. The totem-pole output is optimized to drive the gate of a power MOSFET. The output is low in the off state to provide direct interface to an Nchannel device. Both operate up to a maximum duty cycle range of zero to <50% due to an internal toggle flip-flop which blanks the output off every other clock cycle. The SG1844/45 is specified for operation over the full military ambient temperature range of -55°C to 125°C. The SG3844/45 is designed for the mercial range of 0°C to 70°C. Product Highlight Features - Optimized for Off-Line Control - Low Start-Up Current (<1m A) - Automatic Feed Forward pensation - Trimmed Oscillator - Discharge Current - Pulse-By-Pulse Current Limiting - Enhanced Load Response Characteristics - Undervoltage Lockout with 6V Hysteresis (SG1844 only) - Double Pulse Suppression - High-Current Totem-Pole Output - Internally Trimmed Bandgap Reference - 500k Hz Operation - Under-voltage Lockout - 16 Volts SG1845 - 8.4 Volts - Low Shoot-through Current <75m A Over Temperature Application - Available to MIL-STD-883 - Available to DSCC - Standard Microcircuit Drawing (SMD) - SGR1844/45 Rad-Tolerant Version...