Si9120
Vishay Siliconix
Universal Input Switchmode Controller
FEATURES
D 10- to 450-V Input Range D Current-Mode Contro...
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 +
Under
voltage Comparator Q
S R
SHUTDOWN RESET
Applications informa...