LT4430_15 Datasheet, PDF (1/26 Pages) Linear Technology – Secondary-Side Opto-Coupler Driver

LT4430
Secondary-Side
Opto-Coupler Driver
Features
n _{600mV Reference (1.25% Over Temperature)}
n _{Wide Input Supply Range: 3V to 20V}
n _{Overshoot Control Function Prevents Output}
Overshoot on Start-Up and Short-Circuit Recovery
n _{High Bandwidth Error Amplifier Permits Simple Loop}
Frequency Compensation
n _{Ground-Referenced Opto-Coupler Drive}
n _{10mA Opto-Coupler Drive with Current Limiting}
n _{Low Profile (1mm) ThinSOT}^TM _Package
Applications
n _{48V Input Isolated DC/DC Converters}
n _{Isolated Telecommunication Power Systems}
n _{Distributed Power Step-Down Converters}
n _{Offline Isolated Power Supplies}
n _{Industrial Control Systems}
n _{Automotive and Heavy Equipment}
Description
The LT^®4430 drives the opto-coupler that crosses the gal-
vanic barrier in an isolated power supply. The IC contains
a precision-trimmed reference, a high bandwidth error
amplifier, an inverting gain of 6 stage to drive the opto-
coupler and unique overshoot control circuitry.
The LT4430’s 600mV reference provides ±0.75% initial
accuracy and ±1.25% tolerance over temperature. A high
bandwidth 9MHz error amplifier permits simple frequency
compensation and negligible phase shift at typical loop
crossover frequencies. The opto-coupler driver provides
10mA of output current and is short-circuit protected.
A unique overshoot control function prevents output
overshoot on start-up and short-circuit recovery with a
single capacitor.
The LT4430 is available in the low profile 6-lead TSOT-23
package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Typical Application
Simplified Isolated Synchronous Forward Converter
V_IN
+
ISOLATION
BARRIER
••
V_OUT
+
Isolated Flyback Telecom Converter
Start-Up with Overshoot Control
(See Schematic on Back Page)
LT1952
•
•
FG CG
SYNC
V_CC
LTC3900
V_CC
V_IN
OPTO
LT4430
GND
COMP
OC
FB
4430 TA01
V_IN
50V/DIV
V_OUT
5V/DIV
OVERSHOOT CONTROL
IMPLEMENTED
For more information www.linear.com/LT4430
t = 5ms/DIV
4430 TA01b
4430fc
1