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PT2270 V1.3

- 7 -

May, 2006

Remote Control Decoder IC

PT2270

SINGLE RESISTOR OSCILLATOR

The built-in oscillator circuitry of PT2270 allows a precision oscillator to be constructed with only an

external resistor. For the PT2270 to decode correctly the waveform that was received, the oscillator

frequency of PT2270 must be 1/16 ~ 4 (or 2 to 30) times that of the transmitting PT2260 (or PT2262).

It is a good practice to center the PT2270 oscillator frequency in this window to gain best window

margin at both sides. The typical oscillator with various resistor values are shown below for PT2260,

PT2262 and PT2270.

100

10

1

KHz

3

Voltage

R=510K

R=1M

R=2M

R=3.3M

R=4.7M

6

9

12

15

1

R=2M

R=1M

R=820K

R=680K

R=470K

Voltage (V)

KHz

2

3

4

5

6

10 0

20 0

25 0

30 0

40 0

50 0

PT2262 Encoder OSC Frequency

PT2260 Encoder OSC Frequency

0

20

40

60

80

100

120

140

160

24

68

10

VOLTAGE (V)

Rosc =510 K Ohms

Rosc=620K Ohms

Rosc=1.0 M Ohms

Rosc=1.2 M Ohms

Rosc=2.2 M Ohms

PT2270 Decoder OSC Frequency

Suggested oscillator resistor values are shown below.

PT2260

PT2270

PT2262

PT2270

820KΩ

1.0MΩ

1.2MΩ

120KΩ

1.0MΩ

1.2MΩ

1.5MΩ

160KΩ

2.0MΩ

2.2MΩ

3.3MΩ

390KΩ