PT2212 View Datasheet(PDF) - Princeton Technology

Part Name

Description

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PT2212

Infrared Remote Control Transmitter

Princeton Technology 

Infrared Remote Control Transmitter

Tel: 886-2-66296288

Fax: 886-2-29174598

URL: http://www.princeton.com.tw

PT2212

OSCILLATION

An oscillation circuit may be constructed by connecting a ceramic oscillator to the Oscillator Pins,

namely: OSCO and OSCI. The oscillation frequency is 455KHz. When operation is in a stand-by mode,

the oscillation is also normally stopped, thus, minimizing power consumption.

When the key switch is pressed, the oscillation starts and the operation begins. When the key is

released, the stand-by mode will again be initiated after the completion of the operation. Please refer to

the diagram below.

When fosc=455KHz, the oscillation output is divided into 12 parts and the modulation carrier frequency

is 37.9 ~ 39.2KHz and 1/3 duty. The 455KHz oscillation is divided into 256 parts and the system

fundamental clock is 1.78KHz. The inter-relation between modulation carrier (fc) and the system clock

(Tm) with respect to the oscillation frequency (fosc) is given in the equations below.

MODULATION CARRIER, fc = (1/12) fosc (Duty: 1/3)

SYSTEM CLOCK, Tm= 256/fosc

As stated earlier, 455KHz oscillation, the signal is outputted after the pulse is modulated with a

37.9KHz, 1/3 of the duty 12-divided by the carrier generation circuit. Please refer to the carrier

waveform diagram below.

PT2212 V1.1

- 10 -

May, 2007

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