SM5878AM Datasheet, PDF (13/16 Pages) Nippon Precision Circuits Inc – 3rd-order , 2-channel D/A converter

SM5878AM/AV
Deemphasis Filter (DEEM)
The built-in digital deemphasis filter is designed to
operate at 44.1 kHz. Deemphasis is ON when DEEM
is HIGH, and OFF when DEEM is LOW.
Attenuation (MODE, ATCK, MLEN)
The digital attenuation mode is selected when
MODE is LOW. The attenuator operates by
multiplying the internal 6-bit up/down counter’s
output data with the signal data.
The direction of the 6-bit up/down counter is
controlled by the level on MUTE (down when
MUTE is HIGH, and up when MUTE is LOW). The
count is advanced on the rising edge of ATCK.
When the count reaches 0 (down) or 63 (up), the
counter automatically stops.
Table 2. Attenuator gain
DATT
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
Gain (dB)
0.0
−0.139
−0.280
−0.424
−0.570
−0.718
−0.869
−1.023
−1.180
−1.339
−1.501
−1.667
−1.835
−2.007
−2.183
−2.362
DATT
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
Gain (dB)
−2.545
−2.732
−2.923
−3.118
−3.317
−3.522
−3.731
−3.946
−4.166
−4.391
−4.623
−4.861
−5.105
−5.357
−5.617
−5.884
The gain is set by the counter contents DATT as
follows.
Gain = 20 × log_^D----^A-₆---^T3---^T----_ [dB]
Upon system initialization or when MODE changes
state, DATT is set to 63, which corresponds to the
maximum gain of 0 dB as shown in table 2.
DATT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Gain (dB)
−6.160
−6.444
−6.739
−7.044
−7.360
−7.687
−8.028
−8.383
−8.752
−9.138
−9.542
−9.966
−10.412
−10.881
−11.378
−11.904
DATT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Gain (dB)
−12.465
−13.064
−13.708
−14.403
−15.159
−15.987
−16.902
−17.925
−19.085
−20.424
−22.007
−23.946
−26.444
−29.966
−35.987
−∞
NIPPON PRECISION CIRCUITS—13