SI9120

Si9120 Vishay Siliconix Universal Input Switchmode Controller FEATURES D 10- to 450-V Input Range D Current-Mode Control D 125-mA Output Drive D Internal Start-Up Circuit D Internal Oscillator (1 MHz) D SHUTDOWN and RESET DESCRIPTION The Si9120 is a BiC/DMOS integrated circuit designed for use in low-power, high-efficiency off-line power supplies. High-voltage DMOS inputs allow the controller to work over a wide range of input voltages (10- to 450-VDC). Current-mode PWM control circuitry is implemented in CMOS to reduce quiescent current to less than 1.5 mA. A CMOS output driver provides high-speed switching for MOSFET devices with gate charge, Qg, up to 25 nC, enough to supply 30 W of output power at 100 kHz. These devices, when combined with an output MOSFET and transformer, can be used to implement single-ended power converter topologies (i.e., flyback and forward). The Si9120 is available in both standard and lead (Pb)-free 16-pin plastic DIP and SOIC packages which are specified to operate over the industrial temperature range of −40 _C to 85 _C. FUNCTIONAL BLOCK DIAGRAM OSC IN 9 OSC OUT 8 FB 15 COMP 14 Error Amplifier DISCHARGE 10 OSC 2V − + + − 1.2 V C/L Comparator Clock (1/2 fOSC) R Q S VREF 11 − + 4 V (1%) Ref Gen To VCC Current-Mode Comparator 5 6 OUTPUT −VIN BIAS VCC +VIN 16 Current Sources 7 1 To Internal Circuits 4 VCC 12 13 SENSE − 8.1 V − + 8.6 V Pre-Regulator/Start-Up + Undervoltage Comparator Q S R SHUTDOWN RESET Applications informa...