FOD2743A Datasheet, PDF (1/15 Pages) Fairchild Semiconductor – OPTICALLY ISOLATED ERROR AMPLIFIER

OPTICALLY ISOLATED
ERROR AMPLIFIER
FOD2743A
FOD2743B
FOD2743C
DESCRIPTION
The FOD2743 Optically Isolated Amplifier consists of the popular KA431 precision
programmable shunt reference and an optocoupler. The optocoupler is a gallium arsenide
(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 isolated ac to dc power supplies and dc/dc con-
verters.
When using the FOD2743, power supply designers can reduce the component count and
save space in tightly packaged designs. The tight tolerance reference eliminates the need
for adjustments in many applications. The device comes in a 8-pin dip white package.
FEATURES
• Optocoupler, precision reference and error amplifier in 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 50 ppm/°C max
• FOD2743A: tolerance 0.5%
FOD2743B: tolerance 1%
FOD2743C: tolerance 2%
APPLICATIONS
• Power supplies regulation
• DC to DC converters
8
1
8
1
8
1
FUNCTIONAL BLOCK DIAGRAM
LED 1
COMP 2
GND 3
FB 4
8 NC
7C
6E
5 NC
PIN DEFINITIONS
Pin Number
1
2
3
4
5
6
7
8
Pin Name
LED
COMP
GND
FB
NC
E
C
NC
Pin function description
Anode LED. This pin is the input to the light emitting diode.
Error Amplifier Compensation. This pin is the output of the error amplifier. *
Ground
Voltage Feedback. This pin is the inverting input to the error amplifier
Not connected
Phototransistor Emitter
Phototransistor Collector
Not connected
* The compensation network must be attached between pins 2 and 4.
© 2004 Fairchild Semiconductor Corporation
Page 1 of 15
4/8/04