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Electronic Volume Controller IC
PT2256V
FUNCTION DESCRIPTION
ATTENUATION
The PT2256V volume control circuit consists of ladder resistors and analog switches. The Tap for
loudness function is connected to the Step 10 (-20dB). When the (3.9KΩ) resistor is connected
between LT and AGND pins, the attenuation is given in table below.
The equivalent circuit is shown below:
Attenuation
Attenuation
(dB)
-32
Step
Step
OUT
IN
(dB)
0
-2
-4
-6
0
1
2
3
4
5
6
7
8
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Step 0
Step 1
Step 2
-34
-36
-38
-40
-42
-46
-50
-54
-58
-62
-66
-70
-74
-78
∞
-8
-10
-12
-14
-16
-18
-20
-22
-24
-26
-28
-30
29K
Ω
9
10
11
12
13
14
15
Step 9
LT
Step 10
Step 11
22K
Ω
Step 30
Step 31
AGND
Note:
1. Step 22 has an initial value of -46dB.
PT2256V V1.2
- 4 -
August, 2006
PTC [ PRINCETON TECHNOLOGY CORP ]
