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PT2272 V3.7

- 8 -

June, 2008

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

100

10

1

KHz

3

6

9

12

15

V O L T A G E

R = 510 K

R = 1 M

R = 2 M

R = 3.3 M

R = 4.7 M

1000

100

10

3

6

9

12

15

V O L T A G E

R = 100 K

R = 240 K

R = 510 K

R = 1 M

R = 2 M

KHz

Suggested oscillator resistor values are shown below.

PT2262

PT2272

4.7MΩ

820KΩ *

3.3MΩ

680KΩ *

1.2MΩ

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.