Programmable

Encoder/Decoder

Single chip contains both Encoder and Decoder.

3V to 11 V operation.

On chip oscillator uses non-critical RC components.

Cross interference of

is virtually eliminated

by circuitry which requires 4 valid words to be received,

each within 64ms of the other.

General Description

The

UM3750

Encoder/Decode r

is a

code Transmitter-Receiver system. Working in the trans-

mit (encoder) mode, the

will sequentially encode

and transmit 12 bits of input.

Each of the 12 bits may

be 1 or 0 to allow 4096 different codes.

In the

compared to the local code

a sequential manner

Once

the

system

reset and beain its

Pin Configurations

TX/RX OUTPUT

RECEIVER

INPUT

MODE SELECT

“ss

INPUT

A12

All

A10

Schmitt Trigger input provides excellent noise immunity.

Applications.

alarm control system, security system

cordless telephone, remote control.

Interfaces with RF, ultrasonic, or infrared modulators

I

and demodulators

comparison on the next word.

If all 12 bits are received

correctly, a “valid” signal is generated. This signal clears a

64ms counter and triggers a 3-stage counter. The 3-stage

counter counts the “valid” pluses and when 4 pulses have

been detected, the TX/RX output pin goes low. After the

TX/RX output pin goes low, the next “valid” must be

received within 128ms, giving a one valid in 6 requirement

to keep the TX/RX output pin.

TX/RX

OUTPUT

RECEIVER

INPUT

MODE SELECT

“SS

R.C. INPUT

A12

All

A10

NC

2-3