Silan
Semiconductors
REMOTE CONTROL ENCODER
DESCRIPTION
The SC2268 is a remote control encoder utilizing CMOS
Technology specially designed for use with the SC2128. Using a
special coding technique, SC2268 increases noise immunity to a
very great extent. It is housed in 16-Pins DIP Package and has a
maximum of eight input channels. Its high performance features
makes SC2268 a must in every fan and other electrical home
appliance remote control application.
SC2268
FEATURES
* CMOS Technology
* Low power consumption
* Very high noise immunity
* Wide range of operating voltage: Vcc=2.2 ~ 5.0 Volts
* Transmits signals to a maximum of 8 channels
* Start word custom code options available
DIP-16
APPLICATIONS
* Fan remote control
* Air cleaner
* Humidifier
* Heater
ORDERING INFORMATION
SC2268
SC2268-00
Custom Cord C3=1
Custom Cord C3=0
PIN CONFIGURATION
BLOCK DIAGRAM
Vcc
16
OSCI 15
Vss
9
I1
I2
I3
I4
I5
I6
I7
I8
1
2
3
4
SC2268
5
6
7
8
16
Vcc
15
OSCI
14
OSCO
Tx
13
OUT
OSC
OSCO 14
Timing
circuit
I1 1
I2 2
I3 3
Encoder
Key input
scanning
and
sampling
12
C4
I4 4
Output
Waveform
Generator
13 Tx OUT
11
C5
10
C6
9
Vss
I5 5
I6 6
I7 7
I8 8
12
C4
11
10
C5 C6
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
1
Silan
Semiconductors
ABSOLUTE MAXIMUM RATINGS
Characteristic
Supply Voltage
Input/Output Voltage
Power Dissipation
Operating Temperature
Storage Temperature
SC2268
Symbol
V
CC
V
IN
/V
OUT
P
D
Topr
Tstg
Value
0 ~ 6.0
Vss-0.2V ~ V
CC
+0.3V
500
-20 ~ +70
-55 ~ +125
Unit
V
V
mW
°C
°C
ELECTRICAL CHARACTERISTICS
(Tamb=0 ~ 70°C,V
CC
-V
SS
=3
±
10%V,Unless otherwise specified)
Parameter
Operating Voltage
Operating Current(note)
Standy-by Current
Sinking Current of TxOUT
Input Voltage of
I1 ~I8
High Level
Low level
Symbol
V
CC
I
OP
I
SB
I
SINK
V
IH
V
IL
R
L
R
H
f
OSC
Test conditions
--
OSC On, TxOUT is floating.
I1 ~ I8 = “L” OSC Stops.
TxOUT is floating.
V
OL
=2.2V, V
DD
=3V
V
OL
=1.5V, V
DD
=3V
--
--
--
--
--
Min
2.2
--
0.5
8
4
0.7V
CC
0
30
40
--
Typ
3
0.5
1
15
6
--
--
50
90
455
Max
5
1
3
--
--
V
CC
0.3V
CC
80
150
--
Unit
V
mA
µA
mA
V
kΩ
kΩ
kHz
Input Pull-Low Resistor
Input Pull-High Resistor
Oscillation frequency
Note: For pins I1 ~ I8 : Any one of the said pins is set to HIGH while the others are set to LOW.
PIN DESCRIPTION
Pin No.
1~8
9
11~12
10
Symbol
I1 ~ I8
Vss
C4~C5
C6
I/O
Key input pins.
I
--
I
I
Function
These pins are used to connect a maximum of 8 keys.
(each pin has a built-in pull-low resistor).
Negative power supply.
Select input pin for start word.
These pins have internal pull-low resistor.
Select input pin for start word.
This pins have internal pull-high resistor.
Transmission output pin.
This pin is an open drain (NMOS) output and is used to transmit
signals. The carrier frequency is 38kHz.
Oscillator Input Pin
Oscillator Outpu Pin
Positive power supply.
These pins are used to externally
connect a 455kHz ceramic resonator.
13
15
14
16
TxOUT
OSCI
OSCO
Vcc
O
I
O
--
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
2
Silan
Semiconductors
FUNCTIONAL DESCRIPTION
1. KEY INPUT
Up to eight keys can be directly connected to pins I1 ~
I8. Please refer to the diagram right.
Furthermore, SC2268 has a buit-in pull-low resistor of
about 60K ~ 110KΩ which reduces the need for
external components.
Vcc
1
I1
2
I2
3
I3
4
I4
5
I5
6
I6
7
I7
8
I8
SC2268
SC2268
2. OSCILLATOR
An oscillation circuit can be constructed using the
CMOS inverter and Built-in Feedback resistor, 455kHz
crystal and two 220pf capacitors. The carrier frequency
is 38kHz.
Unless any of the 8 keys (I1~I8) is being operated,
the oscillation is automatically stopped. Thus, power
consumption is considerably reduced.
220pf
455kHz
220pf
15
SC2268
OSCI
OSCO
14
3. TRANMISSION WAVEFORM
When any of the 8 keys (I1 ~ I8) is set to “High”, the TxOUT outputs one start word followed by 2 identical
data words and a space. The code will be continuously outputted until the key is released. If for any
reason, the key was released during the code transmission process, the code that is being transmitted
during the key release action will still be completely outputted. Please refer to the following diagram.
I1 ~ I8
Tx OUT
Start Data Data
Start Data Data
Space
Space
Word Word Word
Word Word Word
20ms
80ms
1 Frame = 80ms
*OSC = 455kHz
Start Data Data
Space
Word Word Word
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
3
Silan
Semiconductors
4. TRANSMISSION CODE WAVEFORM
SC2268
The transmission waveforms of the Start Word and the different Data Words generated when a specific input
key (I1~I8) is pressed are illustrated below (see also Transmission Code Pattern Sectioon):
CLK
start
W1
W2
W3
W4
W5
W6
W7
W8
1
0
X
3X
X
X=0.625ms
5. TRANSMISSION CODE PATTERN
The transmission code pattern of SC2268 is given in the table below.
LSB
C0
0
B0
Data Word
(Key pressed)
W1 (I1)
W2 (I2)
W3 (I3)
W4 (I4)
W5 (I5)
W6 (I6)
W7 (I7)
W8 (I8)
0
0
0
1
1
1
1
1
C1
0
B1
0
1
1
0
0
0
1
1
C2
1
B2
1
0
1
0
1
1
0
0
C3
1
B3
1
1
0
1
0
1
0
1
C4
0
B4
1
1
0
1
0
0
0
0
C5
0
B5
0
0
0
1
1
0
1
0
C6
1
B6
1
0
1
0
1
0
0
1
MSB
C7
1
B7
0
0
0
0
0
1
1
0
0/p1
0/p2
0/p3
0/p4
0/p5
0/p6
0/p7
0/p8
Transmission
Start word
Receiver
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
4
Silan
Semiconductors
6. START WORD CUSTOM CODE
The start word custom code has the following format:
LSB
0
0
1
C3 C4 C5 C6
MSB
1
SC2268
Where: C3 = 1 (default value)
= bonding option available
C4 = “0” when floating or connected to Vss
= “1” when connected to Vcc
C5 = “0” when floating or connected to Vss
= “1” when connected to Vcc
C6 = “0” when connected to Vss
= “1” when floating or connected to Vcc
Note: C4 and C5 have internal pull-low resistors while C6 has an internal pull-high resistor.
The start word custom code table is given below :
C3=0
C4
0
0
0
0
1
1
1
1
C5
0
0
1
1
0
0
1
1
C6
0
1
0
1
0
1
0
1
Custom Code (C0 to C7)
00100001
00100011
00100101
00100111
00101001
00101011
00101101
00101111
C3=1(default)
Custom Code (C0 to C7)
00110001
00110011
00110101
00110111
00111001
00111011
00111101
00111111
OPERATION FLOW CHART
Power on
Stand by
No
Key
press?
Yes
Enable oscillator
Debounce
Code
correct?
Yes
One frame
code transmit
No
No
Key
released?
Yes
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
5
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