and “0”

PT2248
Infrared Remote Control Transmitter
DESCRIPTION
PT2248 is an infrared remote control transmitter
utilizing CMOS Technology. It is capable of 18
functions and a total of 75 commands. Single-shot and
continuous keys are available. Furthermore, multiple
keying is possible.
APPLICATIONS
• Television (TV) Remote Control Transmitter
• Video Cassette Recorder (VCR) Remote Control
Transmitter
FEATURES
• CMOS Technology
• Low Power Consumption
• Wide Range of Operating Supply Voltage allows
Low Voltage Operation (Vcc=2.2 ~ 5.0V)
• Multiple Keying is Possible (Maximum of 6 Keys)
• Less External Components
• An Oscillator can be constructed by connecting a
ceramic resonator at the oscillation circuit
BLOCK DIAGRAM
Tel: 886-66296288‧Fax: 886-29174598‧ http://www.princeton.com.tw‧2F, 233-1, Baociao Road, Sindian, Taipei 23145, Taiwan
PT2248
APPLICATION CIRCUIT
UHF Band 4-Data Transmitter Circuit is recommended.
Notes:
1. R = 200Ω to 3.9KΩ
2. It is highly recommended that the 47µf capacitor be situated near the Vcc.
PT2248 V2.8
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July, 2011
PT2248
ORDER INFORMATION
Valid Part Number
PT2248
PT2248-SN
Package Type
16 Pins, DIP, 300mil
16 Pins, SOP, 150mil
Top Code
PT2248
PT2248-SN
PIN CONFIGURATION
PIN DESCRIPTION
Pin Name
VSS
VCC
Pin No.
1
16
I/O
XT, /XT
2, 3
I, O
K1 ~ K6
4~9
I
T1 ~ T3
10 ~ 12
O
/CODE
13
I
TEST
14
I
TXOUT
15
O
PT2248 V2.8
Description
Negative Supply Voltage Terminal
Positive Supply Voltage Terminal
OSC Input/Output
Terminal for OSC, and used for connecting a 455KHz ceramic resonator, etc.
Key Code Input.
18 Keys can be connected at T1 ~
Key Input Terminals for Key Matrix
T3 x K1 ~ K6
Scan Key Code Output.
Digital Timing Output Terminals for Key
(with a built-in pull-down resistor)
Matrix
Tx/Rx matching Code Common.
Terminal for matching code between transmitting and receiving.
Transmitter Key Code Testing Function.
Keep this terminal open.
Transmitting Signal Output.
Transmitting signal consists of 12-bit per word and is modulated by a 38KHz
carrier wave.
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July, 2011
PT2248
FUNCTION DESCRIPTION
OSCILLATION CIRCUIT
When the self-bias type amplifier is housed by CMOS inverter method, the oscillation circuit can be constructed when a
ceramic resonator has been connected.
When the oscillation frequency is set at 455KHz, the carrier wave of the transmitting signal is set at 38KHz. Unless the keys
are being operated, the oscillation is normally stopped; thereby, reducing power consumption.
KEY INPUT
18 Keys can be connected by Key Inputs K1 ~ K6 and timing signals T1 ~ T3.
Multiple Keying (maximum of 6 keys) is possible for the keys connected to T1 line (Output becomes continuous pulses).
The order of priority of the timing signal line is T1, T2, and T3. When 2 or more keys that are connected to T2 (or T3) line
are pressed simultaneously, the single output will have the preferential order of K1 ~ K6.
Furthermore, the keys connected to T2 and T3 lines are for single signals and no second signal is transmitted unless input
is made after the key is released once.
KEY MATRIX
KEY NO. 1~ 6
These are continuous keys. Multiple Keying is possible.
KEY NO. 7 ~ 18
These are single-shot keys. When an input is made, there is only one signal output.
PT2248 V2.8
-4-
July, 2011
PT2248
TRANSMISSION COMMAND
The Transmission Command consists of one Command Word. One Command Word is composed of Code Bits (3-bit),
Continuous Code (1-bit), Single-Shot Code (2-bit) and the Key Input Code (6-bit). Thus, one Command Word has 12-bit.
C1 ~ C3 are code bits that are adaptable to many models. “H” indicates the continuous signal code while “S1” and “S2” are
single-shot signal codes. D1 ~ D6 are key input data codes in 6 bits.
DATA CODE
Key
No.
1
2
3
4
5
6
7
8
9
H
1
1
1
1
1
1
0
0
0
S1
0
0
0
0
0
0
1
1
1
S2
0
0
0
0
0
0
0
0
0
D1
1
0
0
0
0
0
1
0
0
Data
D2
0
1
0
0
0
0
0
1
0
D3
0
0
1
0
0
0
0
0
1
D4
0
0
0
1
0
0
0
0
0
D5
0
0
0
0
1
0
0
0
0
D6
0
0
0
0
0
1
0
0
0
Output
Form
Continuous
Continuous
Continuous
Continuous
Continuous
Continuous
Single-Shot
Single-Shot
Single-Shot
Key
No.
10
11
12
13
14
15
16
17
18
H
0
0
0
0
0
0
0
0
0
S1
1
1
1
0
0
0
0
0
0
S2
0
0
0
1
1
1
1
1
1
D1
0
0
0
1
0
0
0
0
0
Data
D2
0
0
0
0
1
0
0
0
0
D3
0
0
0
0
0
1
0
0
0
D4
1
0
0
0
00
0
1
0
0
D5
0
1
0
0
0
0
0
1
0
D6
0
0
1
0
0
0
0
0
2
Output
Form
Single-Shot
Single-Shot
Single-Shot
Single-Shot
Single-Shot
Single-Shot
Single-Shot
Single-Shot
Single-Shot
Since multiple keying is possible, Key No. 1 ~ 6 (in combination with D1 ~ D6 data) are capable of sending out 63
commands. Key No. 7 ~ 18 are single-shot keys capable of sending out 12 commands. Thus, a total of 75 commands can
result from a combination of continuous keys (multiple keying) and single-shot keys.
CODE BITS (C1, C2 AND C3)
Code bits can be made at one terminal with diodes connected through T1 ~ T3 timing terminals.
Data of C1, C2 and C3 Code Bits become “1” when diodes are connected to CODE Terminal through the timing signal
terminals -- T1 ~ T3, and “0” when diodes are not connected.
In the diagram above: C1, C2 and C3 are 1, 1, and 1 data respectively.
PT2248 has three (3) Code Bits. The receiving IC -- PT2249A Series (DIP 16 Pins) can only use C2 and C3 Code Bits,
while PT2250A Series (DIP 24 Pins) are able to use only C1 and C2 Code Bits. Therefore, diodes must be connected so
that PT2248 Code Bits Data match with that of the receiving IC.
PT2248 V2.8
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July, 2011
PT2248
The PT2248 Code Bits Connection Table for PT2249A/PT2250A Series Application is given below:
Rx
PT2248 Code Pin
T1 (C1 Code)
T2 (C2 Code)
T3 (C3 Code)
PT2249A
PT2250A
Diode
C2
C3
C1
C2
Diode
Note: where C1, C2, C3 will be “1” if one diode is connected between CODE and Tn pins; n=1 to 3 in PT2248; otherwise, it will be set to “0”.
Note: When communicating with any of the PT2249A Series Receivers, C1 Code Bit Data is not used. Therefore, it is necessary to connect diodes to the
Code terminal corresponding to C1 Code Bit of PT2248. (In this way, the C1 Code Bit of PT2248 transmits “1”. Likewise, when communicating with any of
the PT2250A Series Receivers, C3 Code Bit is not used. Therefore, it is necessary to connect diodes to the Code Terminal corresponding to the C3 Code
Bit of PT2248.)
TRANSMITTING WAVEFORM
The diagram above shows the basic transmitting waveform. A basic transmitting waveform consists of 12-bits serial data.
The time of bit “a” is dependent on the oscillation frequency (fosc) and is given by the following formula:
a=
1
× 192
fosc
DISTINCTION OD BIT “1” AND “0”
One word of the transmission command is in the configuration of (010110010001).
PT2248 V2.8
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July, 2011
PT2248
SINGLE-SHOT SIGNAL
When any one of the single-shot keys is depressed, the above single-shot transmits only 2 command words and then the
transmitting output ends.
CONTINUOUS SIGNAL
When any of the continuous keys is depressed, the above continuous signal transmits a repetitive cycle of 2 command
words and then a pause (with a pause duration of 208a) until the key is released.
If the key is released during code transmission, PT2248 will still continue to send out the last set of 2 command words and
then the transmitting output stops. Please refer to the diagram below:
CARRIER WAVE
About 50 ~ 100mA current is normally applied through an infrared LED in order to extend the infrared reaching distance.
Therefore, reducing the time when the LED is ON leads to the reduction of power consumption. On PT2248, when the
signal is transmitting, each bit is switching by a carrier wave of 1/3 duty. Carrier frequency (fc) is dependent on the
oscillation frequency (fosc) and is given by the following formula:
fosc
a=
( Hz )
12
where: fc = 38KHz at fosc = 455KHz
PT2248 V2.8
-7-
July, 2011
PT2248
ABSOLUTE MAXIMUM RATINGS
(Ta=25℃)
Parameter
Supply Voltage
Input/Output Voltage
Power Dissipation
Operating Temperature
Storage Temperature
Txout Output Current
Symbol
Vcc
VIN
Pd
Topr
Tstg
Iout
Ratings
5.5
Vss-0.5 to Vcc+0.5
200
-40 ~ +85
-65~+150
-5
Unit
V
V
mV
℃
℃
mA
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, Vcc=3V, Ta=25℃)
Parameter
Symbol
Conditions
All Function
Operations
Key On Without
Load
All Keys Off,
Stops oscillation
Min.
Typ.
Max.
Unit
2.2
-
5.0
V
-
-
1.0
mA
-
1.0
10
µA
VIH
-
0.8Vcc
-
Vcc
V
VIL
-
0
-
0.5
V
IIH
VI=3.0V
20
40
60
µA
IIL
VI=0V
-1.0
-
1.0
µA
IOH
Vo=2.0V
-500
-
-
µA
IOL
Vo=2.0V
30
-
-
µA
IOH
Vo=2.0V
-0.1
-
-
mA
IOL
Vo=2.0V
1.0
-
-
mA
Rf
fosc
-
400
500
455
600
KΩ
KHz
Operating Supply Voltage
Vcc
Operating Supply Voltage
Icc
Stand-by Current
ISTB
K1~K6
Voltage
CODE
-
K1~K6
Current
Input
T1~T3
Current
Output
/TXOUT
Current
OSC Feedback Resistor
Oscillation Frequency
PT2248 V2.8
“H”
Level
“L”
Level
“H”
Level
“L”
Level
“H”
Level
“L”
Level
“H”
Level
‘L”
Level
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July, 2011
PT2248
PACKAGE INFORMATION
16 PINS, DIP, 300MIL
Symbol
A
A1
A2
b
c
e
D
E
E1
L
Min.
0.38
2.92
0.36
0.20
18.67
7.62
2.92
Nom.
3.30
2.54 BSC.
19.17
7.62 BSC
7.87
-
Max.
5.33
4.95
0.56
0.36
19.69
8.26
3.81
Notes:
1. Refer to JEDEC MS-001 BB
2. Unit: mm
PT2248 V2.8
-9-
July, 2011
PT2248
16 PINS, SOP, 150MIL
Symbol
A
A1
A2
b
c
e
D
H
E
L
θ
Min.
1.35
0.08
1.20
0.31
0.16
0.40
0°
Typ.
1.45
1.27 BSC.
9.90 BSC.
6.00 BSC.
3.90 BSC.
-
Max.
1.77
0.28
1.65
0.51
0.26
1.27
8°
Notes:
1. Refer to JEDEC MS-012 AC
2. Unit: mm
PT2248 V2.8
- 10 -
July, 2011