PT2257-SL データシートの表示（PDF） - Princeton Technology

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PT2257-SL

Electronic Volume Controller IC

Princeton Technology 

Tel: 886-2-66296288

Fax: 886-2-29174598

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

Electronic Volume Controller IC

PT2257

BYTE FORMAT

Every byte transmitted to the SDA Line consists of 8 bits. Each byte must be followed by an

Acknowledge Bit. The MSB is transmitted first.

ACKNOWLEDGE

During the Acknowledge Clock Pulse, the master (µP) puts a resistive HIGH level on the SDA Line.

The peripheral (audio processor) that acknowledges has to pull-down (LOW) the SDA line during the

Acknowledge Clock Pulse so that the SDA Line is in a Stable Low State during this Clock Pulse. Please

refer to the diagram below.

SC L

1

2

3

4

7

8

9

SD A

MSB

Start

A cknowledgment

from R eceiver

The audio processor that has been addressed has to generate an Acknowledge after receiving each

byte; otherwise, the SDA Line will remain at the High Level during the ninth (9th) Clock Pulse. In this

case, the master transmitter can generate the STOP Information in order to abort the transfer.

TRANSMISSION WITHOUT ACKNOWLEDGE

If you want to avoid the acknowledge detection of the audio processor, a simpler µP transmission may

be used. Wait one clock and do not check the slave acknowledge of this same clock then send the new

data. If you use this approach, there are greater chances of faulty operation as well as decrease in

noise immunity.

PT2257 V1.3

-5-

December, 2006

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