HT12D 12-Bit Decoder IC (HT12D IC) DIP-18 Package

HT12D is a decoder integrated circuit that belongs to 212 series of decoders. This series of decoders are mainly used for remote control system applications, like burglar alarm, car door controller, security system, etc. It is mainly provided to interface RF and infrared circuits. 

They are paired with 212 series of encoders. The chosen pair of encoder/decoder should have the same number of addresses and data format. In simple terms, HT12D converts the serial input into parallel outputs. It decodes the serial addresses and data received by, say, an RF receiver, into parallel data and sends them to output data pins. The serial input data is compared with the local addresses three times continuously.

The input data code is decoded when no error or unmatched codes are found. A valid transmission is indicated by a high signal at the VT pin. HT12D is capable of decoding 12 bits, of which 8 are address bits and 4 are data bits. The data on 4-bit latch type output pins remain unchanged until new is received.

Specifications of HT12D Decoder IC:- 

• Operating voltage: 2.4V~12V
• Low power and high noise immunity CMOS technology
• Low standby current
• Capable of decoding 12 bits of information
• Binary address setting
• Received codes are checked 3 times
• Address/Data number combination
• HT12D: 8 address bits and 4 data bits
• The built-in oscillator needs only 5% resistor
• Valid transmission indicator
• Easy interface with an RF or an infrared transmission medium
• Minimal external components
• Pair with Holteks212 series of encoders
• 18-pin DIP

Working

HT12D decoder will be in standby mode initially, i.e., the oscillator is disabled and a HIGH on DIN pin activates the oscillator. Thus the oscillator will be active when the decoder receives data transmitted by an encoder. The device starts decoding the input address and data. The decoder matches the received address three times continuously with the local address given to pin A0 – A7. If all matches, data bits are decoded and output pins D8 – D11 are activated. This valid data is indicated by making the pin VT (Valid Transmission) HIGH. This will continue till the address code becomes incorrect or no signal is received.

Pin Configuration

Application

• Burglar alarm system
• Smoke and fire alarm system
• Garage door controllers 
• Car door controllers 
• Car alarm system 
• Security system 
• Cordless telephones 
• Other remote control systems