T2525 Datasheet, PDF (1/10 Pages) ATMEL Corporation – IR RECEIVER ASSP

Features
• No External Components Except PIN Diode
• Supply-voltage Range: 4.5 V to 5.5 V
• Automatic Sensitivity Adaptation (AGC)
• Automatic Strong Signal Adaptation (ATC)
• Enhanced Immunity Against Ambient Light Disturbances
• Available for Carrier Frequencies between 30 kHz to 76 kHz; Adjusted by Zener Diode
Fusing
• TTL and CMOS Compatible
• Suitable Minimum Burst Length ³ 6 or 10 Pulses/Burst
Applications
• Audio Video Applications
• Home Appliances
• Remote Control Equipment
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 f₀ which is equivalent to the chosen carrier frequency of the
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
VS
IR Receiver
ASSP
T2525
IN
Input
CGA and
filter
Demodulator
OUT
Micro-
controller
Carrier frequency f₀
Modulated IR signal
min 6/10 pulses
Oscillator
AGC/ATC and digital
control
GND
Rev. 4657D–AUTO–11/03