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PT2268 V2.5

- 4 -

April, 2006

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

PT2268

I7

I6

I5

I4

I3

I2

I1

I8

Furthermore, PT2268 has a built-in pull-low resistor of about 60K ~ 110K

Ω 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.

455KHz

220pF

220pF

P T 2268

OS C1

OS C2

Unless any of the 8 keys (I1 ~ I8) is being operated, the oscillation is automatically stopped. Thus,

power consumption is considerably reduced.