SM5849AF
Asynchronous Sample Rate Converter
NIPPON PRECISION CIRCUITS INC.
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
Filter Characteristics and Converter Efficiency
■ 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)
■ 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
• 256fsi or 384fsi input system clock select
• 256fso or 384fso output system clock select
■ Deemphasis filter
- Down converter LPF I
0.92 times: 48.0 to 44.1kHz
- Down converter LPF II
• IIR-type filter
• 44.1, 48 or 32kHz
0.73 times: 44.1 to 32.0kHz
- Down converter LPF III
■ Digital attenuator
• 11-bit data, 1025 levels
0.67 times: 48.0 to 32.0kHz
- Down converter LPF IV
• Smooth attenuation change
• +12dB gain shift function
■ Direct mute function
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
• ≤ −110dB internal calculation (quantization)
noise
• −98dB (16-bit output), −122dB (20-bit output),
and −146dB (24-bit output) word rounding
noise
■ 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
■ Output S/N ratio (theoretical values)
■ 80-pin QFP
■ Silicon-gate CMOS process
S/N ratio
Output s ignal
16-bit input
word length
20-bit input
word length
24-bit input
word length
word length
16 bits
20 bits
24 bits
94.8dB
97.7dB
97.7dB
97.7dB
109.5dB
109.7dB
97.7dB
109.7dB
110dB
NIPPON PRECISION CIRCUITS—1