Rev. 4657D–AUTO–11/03

Features

Fusing

³ 6 or 10 Pulses/Burst

Applications

Description

The IC T2525 is a complete IR receiver for data communication developed and opti-

mized for use in carrier-frequency-modulated transmission applications. Its function

can be described using the block diagram (see Figure 1). The input stage meets two

main functions. First, it provides a suitable bias voltage for the PIN diode. Secondly,

the pulsed photo-current signals are transformed into a voltage by a special circuit

which is optimized for low-noise applications. After amplification by a Controlled Gain

Amplifier (CGA), the signals have to pass a tuned integrated narrow bandpass filter

with a center frequency f

input signal. The demodulator is used to convert the input burst signal into a digital

envelope output pulse and to evaluate the signal information quality, i.e., unwanted

pulses will be suppressed at the output pin. All this is done by means of an integrated

dynamic feedback circuit which varies the gain as a function of the present environ-

mental condition (ambient light, modulated lamps etc.). Other special features are

used to adapt to the current application to secure best transmission quality. The

T2525 operates in a supply-voltage range of 4.5 V to 5.5 V.

Figure 1. Block Diagram

Input

Micro-

controller

CGA and

filter

Demodulator

Oscillator

AGC/ATC and digital

control

VS

Modulated IR signal

min 6/10 pulses

GND

IN

OUT

Carrier frequency f

0

IR Receiver

ASSP

T2525