The address/data bits of the HT12A are transmitted with a 38kHz carrier for infrared remote con-

troller flexibility.

Address/data programming (preset)

The status of each address/data pin can be individually pre-set to logic ²high² or ²low². If a transmis-

sion-enable signal is applied, the encoder scans and transmits the status of the 12 bits of ad-

dress/data serially in the order A0 to AD11 for the HT12E encoder and A0 to D11 for the HT12A

encoder.

During information transmission these bits are transmitted with a preceding synchronization bit. If

the trigger signal is not applied, the chip enters the standby mode and consumes a reduced current of

less than 1mA for a supply voltage of 5V.

Usual applications preset the address pins with individual security codes using DIP switches or PCB

wiring, while the data is selected by push buttons or electronic switches.

The following figure shows an application using the HT12E:

The transmitted information is as shown:

Pilot

&

Sync.

A0

1

A1

0

A2

1

A3

0

A4

0

A5

0

A6

1

A7

1

AD8

1

AD9

1

AD10

1

AD11

0

HT12A/HT12E

8

April 11, 2000

TE

VD D

A 0A1

A2

A3

A4

A5

A6

A7

VS S

A D 8 AD 9 A D 1 0AD 1 1

OS C 1

OS C 2

DO UT

T r ans m i s s i on

m edi um

VS S