FOD2741A Datasheet, PDF (1/15 Pages) Fairchild Semiconductor – OPTICALLY ISOLATED ERROR AMPLIFIER

OPTICALLY ISOLATED
ERROR AMPLIFIER
FOD2741A
FOD2741B
FOD2741C
DESCRIPTION
The FOD2741 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 100% to 200%. 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 FOD2741, 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 100% to 200%
• 5,000V RMS isolation
• UL approved E90700, Volume 2
CSA approval 1296837
VDE approval 40002463
BSI approval 8702, 8703
• Low temperature coefficient 50 ppm/°C max
• FOD2741A: tolerance 0.5%
FOD2741B: tolerance 1%
FOD2741C: tolerance 2%
APPLICATIONS
• Power supplies regulation
• DC to DC converters
8
1
8
1
8
1
FUNCTIONAL BLOCK DIAGRAM
NC 1
C2
E3
NC ₄
8 LED
7 FB
6 COMP
5 ^GND
PIN DEFINITIONS
Pin Number
1
2
3
4
5
6
7
8
Pin Name
NC
C
E
NC
GND
COMP
FB
LED
Pin function description
Not connected
Phototransistor Collector
Phototransistor Emitter
Not connected
Ground
Error Amplifier Compensation. This pin is the output of the error amplifier. *
Voltage Feedback. This pin is the inverting input to the error amplifier
Anode LED. This pin is the input to the light emitting diode.
* The compensation network must be attached between pins 6 and 7.
© 2003 Fairchild Semiconductor Corporation
Page 1 of 15
12/9/04