Silan
Semiconductors
SC2268
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
1
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.
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
APPLICATIONS
* Fan remote control
* Air cleaner
* Humidifier
* Heater
DIP-16
ORDERING INFORMATION
SC2268-00
Custom Cord C3=1
SC2268
Custom Cord C3=0
PIN CONFIGURATION
BLOCK DIAGRAM
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SC2268
I1
I2
I3
I4
I5
I6
I7
I8
Vcc
OSCI
OSCO
Tx
OUT
C4
C5
C6
Vss
3
2
1
4
7
6
5
8
Key input
scanning
and
sampling
14
15
OSC
Timing
circuit
Encoder
12
11
10
Output
Waveform
Generator
13
16
9
OSCI
OSCO
I1
I2
I3
I4
I5
I6
I7
I8
C4
C5
C6
Tx OUT
Vcc
Vss
Silan
Semiconductors
SC2268
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
2
ABSOLUTE MAXIMUM RATINGS
Characteristic
Symbol
Value
Unit
Supply Voltage
V
CC
0 ~ 6.0
V
Input/Output Voltage
V
IN
/V
OUT
Vss-0.2V ~ V
CC
+0.3V
V
Power Dissipation
P
D
500
mW
Operating Temperature
Topr
-20 ~ +70
C
Storage Temperature
Tstg
-55 ~ +125
C
ELECTRICAL CHARACTERISTICS
(Tamb=0 ~ 70
C,V
CC
-V
SS
=3
10%V,Unless otherwise specified)
Parameter
Symbol
Test conditions
Min
Typ
Max
Unit
Operating Voltage
V
CC
--
2.2
3
5
V
Operating Current(note)
I
OP
OSC On, TxOUT is floating.
--
0.5
1
mA
Standy-by Current
I
SB
I1 ~ I8 = "L" OSC Stops.
TxOUT is floating.
0.5
1
3
A
V
OL
=2.2V, V
DD
=3V
8
15
--
Sinking Current of TxOUT
I
SINK
V
OL
=1.5V, V
DD
=3V
4
6
--
mA
High Level
V
IH
--
0.7V
CC
--
V
CC
Input Voltage of
I1 ~I8
Low level
V
IL
--
0
--
0.3V
CC
V
Input Pull-Low Resistor
R
L
--
30
50
80
k
Input Pull-High Resistor
R
H
--
40
90
150
k
Oscillation frequency
f
OSC
--
--
455
--
kHz
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.
Symbol
I/O
Function
1~8
I1 ~ I8
I
Key input pins.
These pins are used to connect a maximum of 8 keys.
(each pin has a built-in pull-low resistor).
9
Vss
--
Negative power supply.
11~12
C4~C5
I
Select input pin for start word.
These pins have internal pull-low resistor.
10
C6
I
Select input pin for start word.
This pins have internal pull-high resistor.
13
TxOUT
O
Transmission output pin.
This pin is an open drain (NMOS) output and is used to transmit
signals. The carrier frequency is 38kHz.
15
OSCI
I
Oscillator Input Pin
14
OSCO
O
Oscillator Outpu Pin
These pins are used to externally
connect a 455kHz ceramic resonator.
16
Vcc
--
Positive power supply.
Silan
Semiconductors
SC2268
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
3
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 ~ 110K
which reduces the need for
external components.
1
2
3
4
5
6
7
8
SC2268
I1
I2
I3
I4
I5
I6
I7
I8
Vcc
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.
OSCI
455kHz
OSCO
220pf
220pf
SC2268
15
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.
Start
Word
Data
Word
Data
Word
Space
Start
Word
Data
Word
Data
Word
Space
Start
Word
Data
Word
Data
Word
Space
20ms
80ms
1 Frame = 80ms
I1 ~ I8
Tx OUT
*OSC = 455kHz
Silan
Semiconductors
SC2268
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
4
4. TRANSMISSION CODE WAVEFORM
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
X
3X
X=0.625ms
5. TRANSMISSION CODE PATTERN
The transmission code pattern of SC2268 is given in the table below.
LSB
MSB
Transmission
C0
C1
C2
C3
C4
C5
C6
C7
Receiver
Start word
0
0
1
1
0
0
1
1
B0
B1
B2
B3
B4
B5
B6
B7
Data Word
W1 (I1)
0
0
1
1
1
0
1
0
0/p1
(Key pressed)
W2 (I2)
0
1
0
1
1
0
0
0
0/p2
W3 (I3)
0
1
1
0
0
0
1
0
0/p3
W4 (I4)
1
0
0
1
1
1
0
0
0/p4
W5 (I5)
1
0
1
0
0
1
1
0
0/p5
W6 (I6)
1
0
1
1
0
0
0
1
0/p6
W7 (I7)
1
1
0
0
0
1
0
1
0/p7
W8 (I8)
1
1
0
1
0
0
1
0
0/p8
Silan
Semiconductors
SC2268
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0
2000.12.31
5
6. START WORD CUSTOM CODE
The start word custom code has the following format:
0
0
1
C3
1
C4 C5 C6
LSB
MSB
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
C3=1(default)
C4
C5
C6
Custom Code (C0 to C7)
Custom Code (C0 to C7)
0
0
0
00100001
00110001
0
0
1
00100011
00110011
0
1
0
00100101
00110101
0
1
1
00100111
00110111
1
0
0
00101001
00111001
1
0
1
00101011
00111011
1
1
0
00101101
00111101
1
1
1
00101111
00111111
OPERATION FLOW CHART
Power on
Stand by
Key
press?
Enable oscillator
Debounce
Code
correct?
One frame
code transmit
Key
released?
No
Yes
No
Yes
No
Yes
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