SM5849AF
NIPPON PRECISION CIRCUITS INC.
Asynchronous Sample Rate Converter
OVERVIEW
The SM5849AF is a digital audio signal, asynchronous sample rate converter LSI. It supports 16/20/24-bit
word length input data, 16/20/24-bit word length output data, 2kHz to 100kHz input sample rate range, and
4kHz to 200kHz output sample rate range. It also features a built-in digital deemphasis filter and digital attenu-
ator.
FEATURES
Functions
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Filter Characteristics and Converter Efficiency
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Left/right-channel processing (stereo)
2 to 100kHz input sample rate range (fsi)
4 to 200kHz output sample rate range (fso)
0.45 to 2.2-times variable sample rate conversion
ratio (fso/fsi)
Asynchronous input and output timing (clock
inputs)
System clock inputs (input and output clocks inde-
pendent)
• 256fsi or 384fsi input system clock select
• 256fso or 384fso output system clock select
Deemphasis filter
• IIR-type filter
• 44.1, 48 or 32kHz
Digital attenuator
• 11-bit data, 1025 levels
• Smooth attenuation change
• +12dB gain shift function
Direct mute function
Through mode operation
• Direct connection from input to output
Output data clocks (LRCO, BCKO)
• Slave mode: external input
• Master mode: output system clock generated
internally
Dither round-off processing
• Dither round-off ON/OFF selectable
3.3V single supply
80-pin QFP
Silicon-gate CMOS process
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24-bit internal data word length
Deemphasis filter characteristics (IIR filter)
• ±0.03dB gain deviation from ideal filter charac-
teristics
Anti-aliasing LPF characteristics
• Output/input sample rate conversion ratio auto-
matic filter select (6 FIR filters)
- Up converter LPF
1.0 to 2.2 times
- Down converter LPF I
0.92 times: 48.0 to 44.1kHz
- Down converter LPF II
0.73 times: 44.1 to 32.0kHz
- Down converter LPF III
0.67 times: 48.0 to 32.0kHz
- Down converter LPF IV
0.5 times: 48.0 to 24.0kHz
- Down converter LPF V
0.45 times: 48.0 to 22.1kHz
• ±0.00005dB passband ripple
• > 110dB stopband attenuation
Converter noise levels
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≤ −
110dB internal calculation (quantization)
noise
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98dB (16-bit output),
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122dB (20-bit output),
and
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146dB (24-bit output) word rounding
noise
Output S/N ratio (theoretical values)
S/N ratio
Output signal
w ord length
16 bits
20 bits
24 bits
16-bit input
w ord length
94.8dB
97.7dB
97.7dB
20-bit input
w ord length
97.7dB
109.5dB
109.7dB
24-bit input
w ord length
97.7dB
109.7dB
110dB
NIPPON PRECISION CIRCUITS—1
NPC [ NIPPON PRECISION CIRCUITS INC ]
