SM5847AF
NIPPON PRECISION CIRCUITS INC.
High-fidelity Digital Audio, Multi-function Digital Filter
OVERVIEW
The SM5847AF is a 4/8-times oversampling (inter-
polation), 2-channel, linear-phase FIR, multi-func-
tion digital filter for digital audio reproduction
equipment. It features independent left and right-
channel digital deemphasis filters and soft muting
function.
The input/output interface supports input data in
16/18/20/24-bit words, and output data in
18/20/22/24-bit words in either 4-times or 8-times
oversampling selectable output mode.
The internal system clock operates at either 192fs or
256fs selectable speed (where fs is the audio sam-
pling frequency). Plus, the divide-by 1, 2, or 4
counter settings means that external clocks of 768fs/
384fs/192fs (192fs input) and 1024fs/512fs/256fs
(256fs input) are supported.
The SM5847AF operates from a single 3 to 5 V sup-
ply, and is available in 44-pin QFP packages.
FEATURES
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s
s
s
s
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s
Left/right-channel (2-channel processing)
4-times/8-times oversampling (interpolation)
• 8-times interpolation filter
- 3-stage linear-phase FIR configuration
1st stage (fs to 2fs): 169-tap
2nd stage (2fs to 4fs): 29-tap
3rd stage (4fs to 8fs): 17-tap
-
≤
±0.00002 dB passband ripple (0 to
0.4535fs)
-
≥
117 dB stopband attenuation (0.5465fs to
7.4535fs)
• 4-times interpolation filter
- 2-stage linear-phase FIR configuration
1st stage (fs to 2fs): 169-tap
2nd stage (2fs to 4fs): 29-tap
-
≤
±0.00002 dB passband ripple (0 to
0.4535fs)
-
≥
116 dB stopband attenuation (0.5465fs to
3.4535fs)
Digital deemphasis
• IIR filter configuration
• fs = 32kHz, 44.1kHz, 48kHz
• 2-channel independent ON/OFF control
26
×
24-bit parallel multiplier/32-bit accumulator
Overflow limiter
Soft muting
• 2-channel independent ON/OFF control
Input data format
s
s
s
s
s
s
s
s
s
• 2s complement, MSB first
• 3 selectable formats
- LR alternating, 16/18/20/24-bit serial, right-
justified data
- LR alternating, 24-bit serial, left-justified
data
- LR simultaneous, 24-bit serial, left-justified
data
Output data format
• 2s complement, MSB first, LR simultaneous
• 18/20/22/24-bit serial
• BCKO burst (NPC format)
Dither round-off processing
• Dither round-off ON/OFF selectable
25-bit internal data word length
Internal system clock
• 192fs/256fs selectable
• Maximum operating frequency
192fs mode: 37 MHz max (5 V)
20.7 MHz max (3 V)
256fs mode: 27.6 MHz max (5 V)
25 MHz max (3 V)
Jitter-free function
• Jitter-free/Sync mode selectable
Crystal oscillator circuit built-in
3 to 5 V supply
44-pin plastic QFP
CMOS process
ORDERING INFORMATION
D e vice
SM5847AF
P ackag e
44-pin QFP
NIPPON PRECISION CIRCUITS—1
NPC [ NIPPON PRECISION CIRCUITS INC ]
