Datasheet

LM4936
SNAS269A APRIL 2005REVISED APRIL 2013
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A
VD
= 2(R
F
+ R
BS
) / R
i
(10)
Using the component values shown in Figure 3 (R
F
= 20k, R
BS
= 20k, and C
BS
= 0.068µF), a first-order, -6dB
pole is created at 120Hz. Assuming R
i
= 20k, the low frequency differential gain is 4V/V or 12dB. The input (C
i
)
and output (C
OUT
) capacitor values must be selected for a low frequency response that covers the range of
frequencies affected by the desired bass-boost operation.
VOLUME CONTROL
The LM4936 has an internal stereo volume control whose setting is a function of the digital values in the V4 V0
bits. See Table 4.
The LM4936 volume control consists of 31 steps that are individually selected. The range of the steps, are from
0dB - 78dB. The gain levels are 1dB/step from 0dB to -6dB, 2dB/step from -6dB to -36dB, 3dB/step from -36dB
to -47dB, 4dB/step from -47dB to -51dB, 5dB/step from -51dB to -66dB, and 12dB to the last step at -78dB.
Table 4. Volume Control Table
Serial Number V4 V3 V2 V1 V0 Gain (dB)
0 0 0 0 0 0 –90
1 0 0 0 0 1 –90
2 0 0 0 1 0 –68
3 0 0 0 1 1 –63
4 0 0 1 0 0 –57
5 0 0 1 0 1 –51
6 0 0 1 1 0 –47
7 0 0 1 1 1 –45
8 0 1 0 0 0 –42
9 0 1 0 0 1 –39
10 0 1 0 1 0 –36
11 0 1 0 1 1 –34
12 0 1 1 0 0 –32
13 0 1 1 0 1 –30
14 0 1 1 1 0 –28
15 0 1 1 1 1 –26
16 1 0 0 0 0 –24
17 1 0 0 0 1 –22
18 1 0 0 1 0 –20
19 1 0 0 1 1 –18
20 1 0 1 0 0 –16
21 1 0 1 0 1 –14
22 1 0 1 1 0 –12
23 1 0 1 1 1 –10
24 1 1 0 0 0 –8
25 1 1 0 0 1 –6
26 1 1 0 1 0 –5
27 1 1 0 1 1 –4
28 1 1 1 0 0 –3
29 1 1 1 0 1 –2
30 1 1 1 1 0 –1
31 1 1 1 1 1 0
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