e002053.pdf

HT12D

HT12A

Integrated circuits

Special Function

DATASHEET 2/2000

Integrated circuits

Special Function

DATASHEET 2/2000

HT12D

2 12 Series of Decoders

➧

Built-in oscillator needs only 5% resistor

HT12A

2 12 Series of Encoders

Application example

IR Remote Control for Sony MZ-R30 MiniDisc Walk-

man, Elektor Electronics February 2000.

➧

Valid transmission indicator

Easy interface with an RF or an infrared transmis-

sion medium

➧ Minimal external components

Manufacturer

Holtek Semiconductor Inc.,

Manufacturer

Holtek Semiconductor Inc.,

General Description

The 2 12 encoders type HT12A and HT12E are CMOS

LSIs for remote control system applications. They are

capable of encoding information which consists of N

address bits and 12–N data bits. Each address/data

Application example

IR Remote Control for Sony MZ-R30 MiniDisc Walk-

man, Elektor Electronics February 2000.

No.3 Creation Rd. II, Science-based Industrial Park,

Hsinchu, Taiwan, R.O.C. Fax: 886-3-563-1189.

Internet: http://www.holtek.com.tw

No.3 Creation Rd. II, Science-based Industrial Park,

Hsinchu, Taiwan, R.O.C. Fax: 886-3-563-1189.

Internet: http://www.holtek.com.tw

Features (HT12D only)

➧

Operating voltage: 2.4V-12V

Operating voltage 2.4V- 5V

➧ Low power and high noise immunity CMOS tech-

nology

Low power and high noise immunity CMOS tech-

nology

➧ Low standby current

➧

Low standby current: 0.1

A (typ.) at V DD =5V

Capable of decoding 12 bits of information

➧

38kHz carrier for infrared transmission medium

➧

Pair with Holtek’s 2 12 series of encoders

Minimum transmission: one word

➧ Built-in oscillator needs only 5% resistor

➧ Data code has positive polarity

➧

Binary address setting

➧ Received codes are checked 3 times

➧ Address/Data number combination

➧

Minimal external components

8 address bits and 4 data bits

Pin Assignment

➧

18-pin DIP or 20-pin SOP package available

Pin Assignment

Pin Descriptions

Pin Descriptions (HT12A only)

Pin Name

I/O Internal Connection

Description

I/O Internal Connection

Description

Input pins for A0-A7 setting. These pins can be externally set to VSS

or left open

Input pins for A0-A11 setting. They can be externally set to VDD

or VSS

A0 – A7

CMOS IN, pull-high

A0 – A11

NMOS TRANSMISION GATE

Input pins for data D8-D11 setting and transmission enable, active

low. These pins can be externally set to VSS or left open

D8 – D11

CMOS IN, pull-high

D8 – D11

CMOS OUT

Output data pins

DOUT

CMOS OUT

Encoder data serial transmission output

DIN

CMOS IN

Serial data input pin

Latch/Momentary transmission format selection pin.

Latch: floating or VDD. Momentary: VSS

L/MB

CMOS IN pull-high

CMOS OUT

Valid transmission, active high

OSC1

OSCILATOR 1

Oscillator input pin

OSC1

OSCILLATOR

Oscillator input pin

OSC2

OSCILLATOR 1

Oscillator output pin

OSC2

OSCILLATOR

Oscillator output pin

OSCILLATOR 2

455 kHz resonator oscillator input

OSCILLATOR 2

455 kHz resonator oscillator output

VSS

—

Negative power supply (GND)

VSS

—

Negative power supply (GND)

VDD

—

Positive power supply

VDD

—

Positive power supply

➧

Features (HT12A only)

➧

HT12A

HT12D

Integrated circuits

Special Function

DATASHEET 2/2000

Integrated circuits

Special Function

DATASHEET 2/2000

HT12A Block Diagram

HT12D Block Diagram

input can be set to one of the two logic states. The

programmed addresses/data are transmitted together

with the header bits via an RF or an infrared trans-

mission medium upon receipt of a trigger signal. The

capability to select a DATA trigger on the HT12A fur-

ther enhances the application flexibility of the 2 12

series of encoders. The HT12A provides a 38kHz

carrier for infrared systems.

completes its final cycle and then stops as shown in

the transmission timing diagram.

General Description

The HT12D decoder is a CMOS LSIs for remote con-

trol system applications. It is paired with Holtek’s

2 12 series of encoders. For proper operation, a pair

of encoder/decoder with the same number of

addresses and data format should be chosen. The

decoders receive serial addresses and data from a

programmed 2 12 series of encoders that are trans-

mitted by a carrier using an RF or an IR transmis-

sion medium. They compare the serial input data

three times continuously with their local addresses.

If no error or unmatched codes are found, the input

data codes are decoded and then transferred to the

output pins. The VT pin also goes high to indicate a

valid transmission.

The HT12D decoder is capable of decoding informa-

tion consisting of N bits of address and 12–N bits of

data. The HT12D is arranged to provide 8 address

bits and 4 data bits.

Functional description

Operation

The HT12D decoder receives data that are transmitted

by an encoder and interpret the first N bits of code

period as addresses and the last 12–N bits as data,

where N is the address code number. A signal on the

DIN pin activates the oscillator which in turn decodes

the incoming address and data. The decoders will then

check the received address three times continuously. If

the received address codes all match the contents of

the decoder’s local address, the 12–N bits of data are

decoded to activate the output pins and the VT pin is

set high to indicate a valid transmission. This will last

unless the address code is incorrect or no signal is

received. The output of the VT pin is high only when

the transmission is valid. Otherwise it is always low.

Information word

If L/MB=1 the device is in the latch mode (for use

with the latch type of data decoders). When the

transmission enable is removed during a transmis-

sion, the DOUT pin outputs a complete word and

then stops. On the other hand, if L/MB=0 the device

is in the momentary mode (for use with the momen-

tary type of data decoders). When the transmission

enable is removed during a transmission, the DOUT

outputs a complete word and then adds 7 words all

with the ‘1’ data code.

Functional description

Operation

The HT12A encoder begins a 4-word transmission

cycle upon receipt of a transmission enable (D8-D11,

active low). This cycle will repeat itself as long as the

transmission enable (D8-D11) is held low. Once the

transmission enable returns high the encoder output

Output type

The HT12D provides 4 latch type data pins whose

data remain unchanged until new data are received.

Transmission timing for HT12A (L/MB = VSS)

Decoder timing for HT12D

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