The document describes two CMOS LSIs, the HT12A and HT12E, which are encoders for remote control systems. They can encode information consisting of N address bits and 12-N data bits. The HT12A provides a 38kHz carrier for infrared transmission and allows selection of a data trigger, while the HT12E allows selection of a TE trigger. Upon receiving a trigger signal, the encoded addresses and data are transmitted in a series of words. The encoders can operate from 2.4-5V for the HT12A and 2.4-12V for the HT12E, with low power consumption.

1. HT12A/HT12E
212
Series of Encoders
Selection Table
Function Address
No.
Address/
Data No.
Data
No.
Oscillator Trigger Package
Carrier
Output
Negative
Polarity
Part No.
HT12A 8 0 4
455kHz
resonator
D8~D11
18 DIP
20 SOP
38kHz No
HT12E 8 4 0
RC
oscillator
TE
18 DIP
20 SOP
No No
Note: Address/Data represents pins that can be address or data according to the decoder require-
ment.
1 April 11, 2000
General Description
The 212
encoders are a series of 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 ad-
dress/data 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 transmission medium
upon receipt of a trigger signal. The capability
to select a TE trigger on the HT12E or a DATA
trigger on the HT12A further enhances the ap-
plication flexibility of the 212
series of encoders.
The HT12A additionally provides a 38kHz car-
rier for infrared systems.
Features
· Operating voltage
- 2.4V~5V for the HT12A
- 2.4V~12V for the HT12E
· Low power and high noise immunity CMOS
technology
· Low standby current: 0.1mA (typ.) at
VDD=5V
· HT12A with a 38kHz carrier for infrared
transmission medium
· Minimum transmission word
- Four words for the HT12E
- One word for the HT12A
· Built-in oscillator needs only 5% resistor
· Data code has positive polarity
· Minimal external components
· HT12A/E: 18-pin DIP/20-pin SOP package
Applications
· 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

2. Block Diagram
TE trigger
HT12E
DATA trigger
HT12A
Note: The address data pins are available in various combinations (refer to the address/data table).
HT12A/HT12E
2 April 11, 2000
O s c i l l a t o r ¸ 3 D i v i d e r
O S C 1
O S C 2
V D D V S S
1 2 T r a n s m i s s i o n
G a t e C i r c u i t
¸ 1 2 C o u n t e r &
1 o f 1 2 D e c o d e r
B i n a r y D e t e c t o r
T E
A 0
A 7
D O U T
D a t a S e l e c t
& B u f f e r
S y n c .
C i r c u i t
A D 8 A D 1 1
O s c i l l a t o r ¸ 5 7 6 D i v i d e r
V D D V S S
1 2 T r a n s m i s s i o n
G a t e C i r c u i t
¸ 1 2 C o u n t e r &
1 o f 1 2 D e c o d e r
B i n a r y D e t e c t o r
D O U T
D a t a S e l e c t
& B u f f e r
S y n c .
C i r c u i t
L / M B
X 2 X 1
A 0
A 7
D 8 D 1 1

3. Pin Assignment
Pin Description
Pin Name I/O
Internal
Connection
Description
A0~A7 I
CMOS IN
Pull-high
(HT12A)
Input pins for address A0~A7 setting
These pins can be externally set to VSS or left open
NMOS
TRANSMISSION
GATE
PROTECTION
DIODE
(HT12E)
AD8~AD11 I
NMOS
TRANSMISSION
GATE
PROTECTION
DIODE
(HT12E)
Input pins for address/data AD8~AD11 setting
These pins can be externally set to VSS or left open
D8~D11 I
CMOS IN
Pull-high
Input pins for data D8~D11 setting and transmission en-
able, active low
These pins should be externally set to VSS or left open
(see Note)
DOUT O CMOS OUT Encoder data serial transmission output
L/MB I
CMOS IN
Pull-high
Latch/Momentary transmission format selection pin:
Latch: Floating or VDD
Momentary: VSS
HT12A/HT12E
3 April 11, 2000
8 - A d d r e s s
4 - D a t a
A 0
A 1
A 2
A 3
A 4
A 5
A 6
A 7
V S S
V D D
D O U T
X 1
X 2
L / M B
D 1 1
D 1 0
D 9
D 8
1
2
3
4
5
6
7
8
9
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
1 0
8 - A d d r e s s
4 - D a t a
1
2
3
4
5
6
7
8
9
1 0
2 0
1 9
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
N C
V D D
D O U T
X 1
X 2
L / M B
D 1 1
D 1 0
D 9
D 8
N C
A 0
A 1
A 2
A 3
A 4
A 5
A 6
A 7
V S S
H T 1 2 A
1 8 D I P
H T 1 2 A
2 0 S O P
8 - A d d r e s s
4 - A d d r e s s / D a t a
A 0
A 1
A 2
A 3
A 4
A 5
A 6
A 7
V S S
V D D
D O U T
O S C 1
O S C 2
T E
A D 1 1
A D 1 0
A D 9
A D 8
1
2
3
4
5
6
7
8
9
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
1 0
H T 1 2 E
1 8 D I P
8 - A d d r e s s
4 - A d d r e s s / D a t a
1
2
3
4
5
6
7
8
9
1 0
2 0
1 9
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
N C
V D D
D O U T
O S C 1
O S C 2
T E
A D 1 1
A D 1 0
A D 9
A D 8
N C
A 0
A 1
A 2
A 3
A 4
A 5
A 6
A 7
V S S
H T 1 2 E
2 0 S O P

4. Pin Name I/O
Internal
Connection
Description
TE I
CMOS IN
Pull-high
Transmission enable, active low (see Note)
OSC1 I OSCILLATOR 1 Oscillator input pin
OSC2 O OSCILLATOR 1 Oscillator output pin
X1 I OSCILLATOR 2 455kHz resonator oscillator input
X2 O OSCILLATOR 2 455kHz resonator oscillator output
VSS I ¾ Negative power supply, grounds
VDD I ¾ Positive power supply
Note: D8~D11 are all data input and transmission enable pins of the HT12A.
TE is a transmission enable pin of the HT12E.
Approximate internal connections
Absolute Maximum Ratings
Supply Voltage (HT12A) ..............-0.3V to 5.5V Supply Voltage (HT12E) ...............-0.3V to 13V
Input Voltage....................VSS-0.3 to VDD+0.3V Storage Temperature.................-50°C to 125°C
Operating Temperature...............-20°C to 75°C
Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maxi-
mum Ratings² may cause substantial damage to the device. Functional operation of this device
at other conditions beyond those listed in the specification is not implied and prolonged expo-
sure to extreme conditions may affect device reliability.
HT12A/HT12E
4 April 11, 2000
N M O S
T R A N S M I S S I O N
G A T E
C M O S I N
P u l l - h i g h
C M O S O U T O S C I L L A T O R 1
O S C 2
O S C 1
O S C I L L A T O R 2
X 1 X 2
E N
N M O S T R A N S M I S S I O N G A T E
P R O T E C T I O N D I O D E
V D D

5. Electrical Characteristics
HT12A Ta=25°C
Symbol Parameter
Test Conditions
Min. Typ. Max. Unit
VDD Conditions
VDD Operating Voltage ¾ ¾ 2.4 3 5 V
ISTB Standby Current
3V
Oscillator stops
¾ 0.1 1 mA
5V ¾ 0.1 1 mA
IDD Operating Current
3V No load
fOSC=455kHz
¾ 200 400 mA
5V ¾ 400 800 mA
IDOUT Output Drive Current 5V
VOH=0.9VDD (Source) -1 -1.6 ¾ mA
VOL=0.1VDD (Sink) 2 3.2 ¾ mA
VIH ²H² Input Voltage ¾ ¾ 0.8VDD ¾ VDD V
VIL ²L² Input Voltage ¾ ¾ 0 ¾ 0.2VDD V
RDATA
D8~D11 Pull-high
Resistance
5V VDATA=0V ¾ 150 300 kW
HT12E Ta=25°C
Symbol Parameter
Test Conditions
Min. Typ. Max. Unit
VDD Conditions
VDD Operating Voltage ¾ ¾ 2.4 5 12 V
ISTB Standby Current
3V
Oscillator stops
¾ 0.1 1 mA
12V ¾ 2 4 mA
IDD Operating Current
3V No load
fOSC=3kHz
¾ 40 80 mA
12V ¾ 150 300 mA
IDOUT Output Drive Current 5V
VOH=0.9VDD (Source) -1 -1.6 ¾ mA
VOL=0.1VDD (Sink) 1 1.6 ¾ mA
VIH ²H² Input Voltage ¾ ¾ 0.8VDD ¾ VDD V
VIL ²L² Input Voltage ¾ ¾ 0 ¾ 0.2VDD V
fOSC Oscillator Frequency 5V ROSC=1.1MW ¾ 3 ¾ kHz
RTE TE Pull-high Resistance 5V VTE=0V ¾ 1.5 3 MW
HT12A/HT12E
5 April 11, 2000

6. Functional Description
Operation
The 212
series of encoders begin a 4-word transmission cycle upon receipt of a transmission enable
(TE for the HT12E or D8~D11 for the HT12A, active low). This cycle will repeat itself as long as the
transmission enable (TE or D8~D11) is held low. Once the transmission enable returns high the en-
coder output completes its final cycle and then stops as shown below.
HT12A/HT12E
6 April 11, 2000
4 w o r d s 4 w o r d s
E n c o d e r
D O U T
T r a n s m i t t e d
C o n t i n u o u s l y
< 1 w o r d
T E
Transmission timing for the HT12E
E n c o d e r
D O U T
T r a n s m i t t e d
C o n t i n u o u s l y
< 1 w o r d
D 8 ~ D 1 1
K e y - i n
1 w o r d
w i t h 3 8 k H z c a r r i e r
1 w o r d
Transmission timing for the HT12A (L/MB=Floating or VDD)
E n c o d e r
D O U T
T r a n s m i t t e d
C o n t i n u o u s l y
D 8 ~ D 1 1
K e y - i n
1 w o r d
< 1 w o r d
7 w o r d s
1 w o r d
7 w o r d s
( a l l d a t a = 1 )
( a l l d a t a = 1 )
Transmission timing for the HT12A (L/MB=VSS)

7. Information word
If L/MB=1 the device is in the latch mode (for use with the latch type of data decoders). When the trans-
mission enable is removed during a transmission, 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 momentary
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 ²1² data code.
An information word consists of 4 periods as illustrated below.
Address/data waveform
Each programmable address/data pin can be externally set to one of the following two logic states as
shown below.
HT12A/HT12E
7 April 11, 2000
1 / 3 b i t s y n c . p e r i o d
p i l o t p e r i o d ( 1 2 b i t s ) a d d r e s s c o d e p e r i o d
p e r i o d
d a t a c o d e
Composition of information
" O n e "
" Z e r o "
f O S C
A d d r e s s /
D a t a B i t
Address/Data bit waveform for the HT12E
" O n e "
" Z e r o "
f O S C
D a t a B i t
D a t a B i t
" O n e "
" Z e r o "
A d d r e s s B i t
A d d r e s s B i t
3 8 k H z
c a r r i e r
Address/Data bit waveform for the HT12A

8. 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
T E
V D D A 0 A 1 A 2 A 3 A 4 A 5 A 6 A 7 V S S A D 8 A D 9 A D 1 0 A D 1 1
O S C 1 O S C 2
D O U T
T r a n s m i s s i o n
m e d i u m
V D D
V S S

9. Address/Data sequence
The following provides the address/data sequence table for various models of the 212
series of
encoders. The correct device should be selected according to the individual address and data require-
ments.
Part No.
Address/Data Bits
0 1 2 3 4 5 6 7 8 9 10 11
HT12A A0 A1 A2 A3 A4 A5 A6 A7 D8 D9 D10 D11
HT12E A0 A1 A2 A3 A4 A5 A6 A7 AD8 AD9 AD10 AD11
Transmission enable
For the HT12E encoders, transmission is enabled by applying a low signal to the TE pin. For the
HT12A encoders, transmission is enabled by applying a low signal to one of the data pins D8~D11.
Two erroneous HT12E application circuits
The HT12E must follow closely the application circuits provided by Holtek (see the ²Application cir-
cuits²).
· Error: AD8~AD11 pins input voltage > VDD+0.3V
HT12A/HT12E
9 April 11, 2000
H T 1 2 E
O S C 2
O S C 1
T E
V S S
V D D
A D 1 1
A D 1 0
A D 9
A D 8
1 2 V

10. · Error: The IC¢s power source is activated by pins AD8~AD11
Flowchart
· HT12A · HT12E
Note: D8~D11 are transmission enables of the HT12A.
TE is the transmission enable of the HT12E.
HT12A/HT12E
10 April 11, 2000
H T 1 2 E
O S C 2
O S C 1
V S S
T E
V D D
1 2 V
A D 1 1
A D 1 0
A D 9
A D 8
S t a n d b y m o d e
D a t a e n a b l e ?
N o
N o
D a t a w i t h c a r r i e r
s e r i a l o u t p u t
D a t a s t i l l e n a b l e d ?
L / M B = G N D ?
S e n d t h e
l a s t c o d e
N o
Y e s
Y e s
Y e s
S e n d ² 1 ² 7 t i m e s f o r
a l l o f t h e d a t a c o d e s
P o w e r o n
S t a n d b y m o d e
T r a n s m i s s i o n
e n a b l e d ?
N o
N o
Y e s
Y e s
4 d a t a w o r d s
t r a n s m i t t e d
T r a n s m i s s i o n
s t i l l e n a b l e d
4 d a t a w o r d s
t r a n s m i t t e d
c o n t i n u o u s l y
P o w e r o n

11. Oscillator frequency vs supply voltage
The recommended oscillator frequency is fOSCD (decoder) @ 50 fOSCE (HT12E encoder)
@
1
3
fOSCE (HT12A encoder)
HT12A/HT12E
11 April 11, 2000
2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3
1 . 0 0
2 . 0 0
( 3 k H z ) 3 . 0 0
4 . 0 0
5 . 0 0
6 . 0 0
7 . 0 0
V D D ( V D C )
f O S C
( S c a l e )
2 . 0 M
1 . 5 M
1 . 2 M
1 . 0 M
9 1 0 k
8 2 0 k
7 5 0 k
6 8 0 k
6 2 0 k
5 6 0 k
5 1 0 k
4 7 0 k
R O S C ( W )

12. Application Circuits
Note: Typical infrared diode: EL-1L2 (KODENSHI CORP.)
Typical RF transmitter: JR-220 (JUWA CORP.)
HT12A/HT12E
12 April 11, 2000
4 5 5 k W
H T 1 2 A
1 0 M W
1 0 0 p F
1 0 0 p F
8 0 5 0
1 0 0 W
1
2
3
4
5
6
7
8
9
A 0
A 4
A 5
A 6
A 7
V S S
A 1
A 2
A 3
V D D
D O U T
X 1
X 2
L / M B
D 1 1
D 1 0
D 9
D 8
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
1 0
1 0 k W
V D D
T r a n s m i t t e r C i r c u i t
H T 1 2 E
A 0
A 1
A 2
A 3
A 4
A 5
A 6
A 7
V S S
V D D
D O U T
O S C 1
O S C 2
T E
A D 1 1
A D 1 0
A D 9
A D 8
1
2
3
4
5
6
7
8
9
1 8
1 7
1 6
1 5
1 4
1 3
1 2
1 1
1 0
R O S C
V D D

13. HT12A/HT12E
13 April 11, 2000
Copyright Ó 2000 by HOLTEK SEMICONDUCTOR INC.
The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek
assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are
used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications
will be suitable without further modification, nor recommends the use of its products for application that may pres-
ent a risk to human life due to malfunction or otherwise. Holtek reserves the right to alter its products without prior
notification. For the most up-to-date information, please visit our web site at http://www.holtek.com.tw.
Holtek Semiconductor Inc. (Headquarters)
No.3 Creation Rd. II, Science-based Industrial Park, Hsinchu, Taiwan, R.O.C.
Tel: 886-3-563-1999
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