SI9112

Si9112 Vishay Siliconix High-Voltage Switchmode Controller FEATURES D 9- to 80-V Input Range D Current-Mode Control D High-Speed, Source-Sink Output Drive D High Efficiency Operation (> 80%) D Internal Start-Up Circuit D Internal Oscillator (1 MHz) D SHUTDOWN and RESET DESCRIPTION The Si9112 is a BiC/DMOS integrated circuit designed for use in high-efficiency switchmode power converters. A high-voltage DMOS input allows this controller to work over a wide range of input voltages (9- to 80-VDC). Current-mode PWM control circuitry is implemented in CMOS to reduce internal power consumption to less than 10 mW. A CMOS output driver provides high-speed switching of MOSPOWER devices large enough to supply 50 W of output power. When combined with an output MOSFET and transformer, the Si9112 can be used to implement single-ended power converter topologies (i.e., flyback, forward, and cuk). The Si9112 is available in both standard and lead (Pb)-free 14-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 8 OSC OUT 7 FB 14 COMP 13 DISCHARGE 9 Error Amplifier 10 − + 4 V (2%) Ref Gen 2V − + + − 1 Current Sources To Internal Circuits 1.2 V C/L Comparator Current-Mode Comparator OSC Clock (1/2 fOSC) VREF To VCC 4 R Q S 5 OUTPUT −VIN BIAS 3 VCC VCC 6 SENSE +VIN 2 8.1 V − + 8.7 V − + Undervoltage Comparator Q S R 11 12 SHUTDOWN RESET Pre-Regulator/Start-Up Applicatio...