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Remote Control Decoder
PT2272
SINGLE RESISTOR OSCILLATOR
The built-in oscillator circuitry of PT2272 allows a precision oscillator to be constructed with only an
external resistor. For the PT2272 to decode correctly the waveform that was received, the oscillator
frequency of PT2272 must be 2.5~8 times that of the transmitting PT2262. It is a good practice to
center the PT2272 oscillator frequency in this window to gain best window margin at both sides. The
typical oscillator with various resistor values is shown below for both PT2262 and PT2272.
Encoder OSC Frequency
Decoder OSC Frequency
KHz
100
KHz
1000
R = 510 K
R = 1 M
R = 2 M
R = 100 K
R = 240 K
R = 510 K
R = 1 M
100
10
R = 3.3 M
R = 4.7 M
10
1
R = 2 M
3
6
9
12
15
3
6
9
12
15
V O L T A G E
V O L T A G E
Suggested oscillator resistor values are shown below.
PT2262
4.7MΩ
3.3MΩ
1.2MΩ
PT2272
820KΩ *
680KΩ *
200KΩ **
Note:
* -- Operates when PT2272's VCC=5V to 15V
** -- Operates when PT2272's VCC= 4V to 15V
This means that if the PT2272 supply voltage is lower than 5V, you have to use a lower oscillator
resistor value for both PT2262 and PT2272.
PT2272 V3.7
- 8 -
June, 2008
PTC [ PRINCETON TECHNOLOGY CORP ]
