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PT2256 V1.7

- 6 -

August, 2006

Electronic Volume Controller IC

PT2256

DC OUTPUT FOR VOLUME LEVEL

The DC Output for the Volume Level Meter is internally connected to the D/A Converter. PT2256 has 8

stages of output voltage with each stage corresponding to a particular volume level. Please refer to the

table below:

Step

Attenuation (dB)

Output Voltage (V)

0-3

0-6

7/8 VDD

4-7

8-14

6/8 VDD

8-11

16-22

5/8 VDD

12-15

24-30

4/8 VDD

16-19

32-38

3/8 VDD

20-23

40-50

2/8 VDD

24-27

54-66

1/8 VDD

28-31

70-∞

0

UP/DOWN VOLUME CONTROL

PT2256 features two Volume Control Pins, namely: UP and DN. UP is the control pin used to increase

volume level while the DN is the control pin used to decrease the volume level. Thus, volume level may

regulated using the Up or Down Keys. These keys are operated on a 1 step/1 push volume level

control when UP or DN keys are set to “L” Level. If the keys are continuously pressed (input “Low”),

then the volume level continuously steps up or down as the case maybe. Please refer to the diagram

below for the timing of the key input.

tT

a

/UP, /DN Input

Volume Level

Control

Notes:

1. t= Preventive Time for Chattering (2.2 x 1/fosc )

2. T= Switching Time to Automatic Mode (10 x 1/fosc)

3. a=Up, Down Speed (2x1/fosc)