TV remote control Circuit diagram using SL490

Circuit diagram TV remote control using SL490

Circuit diagram TV remote control using SL490

This is a 32 channel infrared remote controller circuit fundamentally includes key pad, decoder, transducer stage, an output and a battery.

Every key pad button generates 5 bit binary code and IC1 sends this code to the IR leds through D1 and D2 diodes.  Code is shaped from 6 pulses with 5 gaps. Pulse position modulation – PPM technique is used for transferring data. Data information occurs at gaps. For logic 0, long gap, for logic 1 short gap is generated. SL490 includes an auto stand-by circuitry. When the buttons are not used for a while, IC will swich to stand-by mode and stand by current will be 6uA.

Pulse and gap lengths are calibrated by using  potentiometer.