Si9112
Vishay Siliconix
High-Voltage Switchmode Controller
FEATURES
D 9- to 80-V Input Range D Current-Mode Control D H...
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
− +
Under
voltage Comparator Q
S R
11 12
SHUTDOWN RESET
Pre-Regulator/Start-Up Applicatio...