KA3511DS Datasheet, PDF (1/18 Pages) Fairchild Semiconductor – Intelligent Voltage Mode PWM IC

KA3511DS
Intelligent Voltage Mode PWM IC
www.fairchildsemi.com
Features
• Complete PWM control and house keeping circuitry
• Few external components
• Precision voltage reference trimmed to 2%
• Dual output for push-pull operation
• Each output TR for 200mA sink current
• Variable duty cycle by dead time control
• Soft start capability by using dead time control
• Double pulse suppression logic
• Over voltage protection for 3.3V / 5V / 12V
• Under voltage protection for 3.3V / 5V / 12V
• One more external input for various protection (PT)
• Remote on/off control function (PS-ON)
• Latch function controlled by remote and protection input
• Power good signal generator with hysteresis
Precision reference section
The reference voltage trimmed to ± 2%
(4.9V ≤ Vref ≤ 5.1V)
PG (Power good signal generator) section
Power good signal generator is to monitor the voltage level
of power supply for safe operation of a microprocessor.
KA3511DS requires few external components to accomplish
a complete housekeeping circuits for SMPS.
Description
The KA3511DS is a fixed frequency improved performance
pulse width modulation control circuit with complete
housekeeping circuitry for use in the secondary side of
SMPS (Switched mode power supply). It contains various
functions, which are precision voltage reference, over
voltage protection, under voltage protection, remote on/off
control, power good signal generator and etc.
OVP (Over voltage protection) section
It has OVP functions for +3.3V,+5V,+12V and PT outputs.
The circuit is made up of a comparator with four detecting
inputs and without hysteresis voltage. Especially, PT (Pin18)
is prepared for an extra OVP input or another protection
signal.
UVP (Under voltage protection) section
It also has UVP functions for +3.3V, +5V, +12V outputs. The
block is made up of a comparator with three detecting inputs
and without hysteresis voltage.
Remote on/off section
Remote on/off section is used to control SMPS externally. If
a high signal is supplied to the remote on/off input, PWM
signal becomes a high state and all secondary outputs are
grounded. The remote on/off signal is transferred with some
on-delay and off-delay time of 8ms, 24ms respectively.
24-SDIP
1
©2001 Fairchild Semiconductor Corporation
Rev. 1.0.0