Tel: 886-2-66296288
Fax: 886-2-29174598
URL: http://www.princeton.com.tw
Remote Control Encoder
PT2268
DESCRIPTION
PT2268 is a remote control encoder utilizing CMOS Technology specially designed for use with the
PT2128. Using a special coding technique, PT2268 increases noise immunity to a very great extent. It
is housed in 16-Pins DIP Package and has a maximum of eight (8) input channels. Its high
performance features make PT2268 a MUST in every fan and other electrical home appliance remote
control application.
PTC provides a new version of PT2268 which can be identified by the “B” mark on the lower right hand
corner of the IC’s topcode (beside the date code). Please refer to the diagram on the Order Information
Section. The difference between the old and new version is the external application circuit in the OSC1
and OSC2 pins. (see Oscillator Section)
FEATURES
•
•
•
•
•
•
CMOS technology
Low power consumption
Very high noise immunity
Wide range of operating voltage: Vcc=2.2 ~ 5.0V
Transmits signals to a maximum of 8 channels
Start word custom code options available (Please contact PTC for details.)
APPLICATIONS
•
•
•
•
Fan remote control
Air cleaner
Humidifier
Heater
PT2268 V2.5
-1-
April, 2006
Tel: 886-2-66296288
Fax: 886-2-29174598
URL: http://www.princeton.com.tw
Remote Control Encoder
PT2268
BLOCK DIAGRAM
OSC1
OSC
OSC2
Timing
Circuit
VCC
VSS
I1
I2
I3
I4
I5
I6
I7
I8
Encoder
Key Input
Scanning
and Sampling
Output
Waveform
Generator
Tx OUT
C4
C5
C6
PT2268 V2.5
-2-
April, 2006
Tel: 886-2-66296288
Fax: 886-2-29174598
URL: http://www.princeton.com.tw
Remote Control Encoder
PT2268
PIN CONFIGURATION
I1
I2
I3
I4
I5
I6
I7
I8
1
2
3
4
5
6
7
8
PT 2268
16
15
14
13
12
11
10
9
VC C
OSC1
OSC1
T xOU T
C4
C5
C6
VS S
PIN DESCRIPTION
Pin Name
I1 ~ I8
VSS
C4 ~ C5
C6
Tx OUT
OSC1
OSC2
VCC
I/O
I
-
I
I
O
I
O
-
Description
Key Input Pins.
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 resistors.
Select Input Pin for Start Word
This pin has an 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 38 KHz.
Oscillator No.1 Pin
These pins are used to externally connect a
455 KHz Ceramic Resonator
Oscillator No.2 Pin
Positive Power Supply
Pin No.
1~8
9
12 ~ 11
10
13
15
14
16
PT2268 V2.5
-3-
April, 2006
Tel: 886-2-66296288
Fax: 886-2-29174598
URL: http://www.princeton.com.tw
Remote Control Encoder
PT2268
FUNCTION DESCRIPTION
KEY INPUT
Up to eight (8) keys can be directly connected to pins I1 ~ I8. Please refer to the diagram below.
VCC
I1
I2
I3
I4
I5
I6
I7
I8
PT2268
Furthermore, PT2268 has a built-in pull-low resistor of about 60K ~ 110KΩ which reduces the need for
external components.
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.
P T 2268
O S C1
O S C2
220pF
455KHz
220pF
Unless any of the 8 keys (I1 ~ I8) is being operated, the oscillation is automatically stopped. Thus,
power consumption is considerably reduced.
PT2268 V2.5
-4-
April, 2006
Tel: 886-2-66296288
Fax: 886-2-29174598
URL: http://www.princeton.com.tw
Remote Control Encoder
PT2268
TRANSMISSION WAVEFOM
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
T x O UT
Start 1st 2nd Space Start 1st 2nd Space
Word Word Word
Word Word Word
Start 1st 2nd Space
Word Word Word
20ms
80ms
1 Frame=80ms
Note: OSC=455KHz
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 Section).
CLK
START
W1
W2
W3
W4
W5
W6
W7
W8
1
0
X
3X
X
X=0.625ms
PT2268 V2.5
-5-
April, 2006
