FOD2743A, FOD2743B, FOD2743C — Optically Isolated Error Amplifier
©2004 Fairchild Semiconductor Corporation www.fairchildsemi.com
FOD2743A, FOD2743B, FOD2743C Rev. 1.0.1
August 2008
FOD2743A, FOD2743B, FOD2743C
Optically Isolated Error Amplifier
Features
■
Optocoupler, precision reference and error amplifier in
a single package
■
2.5V reference
■
CTR 50% to 100% at 1mA
■
5,000V RMS isolation
■
UL approval E90700, Vol. 2
CSA approval 1296837
VDE approval pending
BSI approval pending
■
Low temperature coefficient 50ppm/°C max
■
FOD2743A: tolerance 0.5%
FOD2743B: tolerance 1%
FOD2743C: tolerance 2%
Applications
■
Power supplies regulation
■
DC to DC converters
Description
The FOD2743 Optically Isolated Amplifier consists of the
popular KA431 precision programmable shunt reference
and an optocoupler. The optocoupler is a gallium ars-
enide (GaAs) light emitting diode optically coupled to a
silicon phototransistor. It comes in 3 grades of reference
voltage tolerance = 2%, 1%, and 0.5%.
The Current Transfer Ratio (CTR) ranges from 50% to
100%. It also has an outstanding temperature coefficient
of 50 ppm/°C. It is primarily intended for use as the error
amplifier/reference voltage/optocoupler function in iso-
lated AC to DC power supplies and dc/dc converters.
When using the FOD2743, power supply designers can
reduce the component count and save space in tightly
packaged designs. The tight tolerance reference elimi-
nates the need for adjustments in many applications.
The device comes in an 8-pin dip white package.
Functional Bock Diagram Package Outlines
8
8
1
8
1
1
1
2
3
4 5
6
7
8
NC
C
E
NC
LED
COMP
GND
FB
