PT2248 データシートの表示（PDF） - Princeton Technology

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PT2248

Infrared Remote Control Transmitter

Princeton Technology 

Infrared Remote Control Transmitter

CONTINUOUS SIGNAL

PT2248 Key On

/TX OU T

48a 80a 48a

20 8a

Tel: 886-2-66296288

Fax: 886-2-29174598

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

PT2248

48a 80a 48a

2 Command Words

P aus e

When any of the continuous keys is depressed, the above continuous signal transmits a repetitive

cycle of 2 command words and then a pause (with a pause duration of 208a) until the key is released.

If the key is released during code transmission, PT2248 will still continue to send out the last set of 2

command words and then the transmitting output stops. Please refer to the diagram below:

PT2248 Key On

/TXOUT

48a 80a 48a

208a

48a 80a 48a

48a 80a 48a

2 Command Words Pause

2 Command Words

CARRIER WAVE

About 50 ~ 100mA current is normally applied through an infrared LED in order to extend the infrared

reaching distance. Therefore, reducing the time when the LED is ON leads to the reduction of power

consumption. On PT2248, when the signal is transmitting, each bit is switching by a carrier wave of 1/3

duty. Carrier frequency (fc) is dependent on the oscillation frequency (fosc) and is given by the

following formula:

fosc

a=

(Hz)

12

where: fc = 38KHz at fosc = 455KHz

Tran sm ittin g Sig n a l

Pu lse M od u la te d

Transmitting Signal

PT2248 V2.7

-9-

June, 2005

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