FOD2742A_08 Datasheet, PDF (1/15 Pages) Fairchild Semiconductor – Optically Isolated Error Amplifier

FOD2742A, FOD2742B, FOD2742C
Optically Isolated Error Amplifier
December 2008
Features
■ Optocoupler, precision reference and error amplifier in
single package
■ 2.5V reference
■ CTR 100% to 200%
■ 2,500V RMS isolation
■ UL approval E90700, Volume 2
■ BSI approval 8661, 8662
■ VDE approval 136616
■ CSA approval 1113643
■ Low temperature coefficient 50 ppm/°C max.
■ FOD2742A: tolerance 0.5%
FOD2742B: tolerance 1%
FOD2742C: tolerance 2%
Applications
■ Power supplies regulation
■ DC to DC converters
Description
The FOD2742 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 converters.
When using the FOD2742, 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 small outline
package.
Schematic
NC 1
C2
E3
NC 4
8 ^LED
7 FB
6 COMP
5 GND
Package Outline
©2003 Fairchild Semiconductor Corporation
FOD2742A, FOD2742B, FOD2742C Rev. 1.0.0
www.fairchildsemi.com