SI9118_11 Datasheet, PDF (1/11 Pages) Vishay Siliconix – Programmable Duty Cycle Controller

Si9118, Si9119
Vishay Siliconix
Programmable Duty Cycle Controller
DESCRIPTION
The Si9118/Si9119 are a BiC/DMOS current-mode pulse
width modulation (PWM) controller ICs for high-frequency
dc/dc converters. Single-ended topologies (forward and
flyback) can be implemented at frequencies up to 1 MHz.
The controller operates in constant frequency mode during
the full load and automatically switches to pulse skipping
mode under light load to maintain high efficiency throughout
the full load range. The maximum duty cycle is easily
programmed with a resistor divider for optimum control.
The push-pull output driver provides high-speed switching to
external MOSPOWER devices large enough to supply 50 W
of output power. Shoot-through current for internal push-pull
stage is almost eliminated to minimize quiescent supply
current.
The push-pull output driver provides high-speed switching to
external MOSPOWER devices large enough to supply 50 W
of output power. Shoot-through current for internal push-pull
stage is almost eliminated to minimize quiescent supply
current.
The high-voltage DMOS transistor permits direct operation
from bus voltages of up to 200 V. Other features include a
1.5 % accurate voltage reference, 2.7 MHz bandwidth error
amplifier, standby mode, soft-start and undervoltage lockout
circuits.
The Si9118/Si9119 are available in both standard and lead
(Pb)-free packages.
FEATURES
• 10 to 200 V Input Range
• Current-Mode Control
• Internal Start-Up Circuit
• Buffer Slope Compensation Voltage
• Soft-Start
• 2.7 MHz Error Amp
• 500 mA Output Drive Current
• Light Load Frequency Fold-Back
• Low Quiescent Current
• Programmable Maximum Duty Cycle, with 80 % as
Default
FUNCTIONAL BLOCK DIAGRAM
4
NI
5
Error
Amplifier
–
+
LIMIT CS
6
10 11
1.0 - 2.0 V
+–
2
PWM
–
+
3
V_REF
7
SS/EN
Ref
Gen
4.6 V
23µA
100 mV
–V_IN
600 mV
Pulse Skip
+
–
EN
I_MAX
+
–
16
V_CC
1
+V_IN
–
+
–
+
–
+
8.6 V
Undervoltage
Lockout
9.3 V (V_REG)
SYNC (Si9119) MAX
12
13
OSC
9
R_OSC
8 _COSC
R
Q
S
15
DR
14
-V _IN
Substrate
Document Number: 70815
www.vishay.com
S11-0975–Rev. E, 16-May-11
1
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000