SM5846AP
Multi-function Digital Filter
OVERVIEW
The SM5846AP is a multi-function digital filter that incorporates 4/8 times oversampling digital audio signal
reproduction, digital deemphasis, digital attenuation and soft mute functions. The I/O interface allows serial
data transmission of 16/20/24/32-bit input data and 20/24-bit output data.
FEATURES
Functions
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Filter Construction
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8-times oversampling (interpolation)
Switchable 8/4 times oversampling output
Two master clock frequencies
(refer to Clock Functions)
• 384fs/512fs (normal-speed sampling)
• 192fs/256fs (high-speed sampling)
Digital deemphasis
• Compatible with 32/44.1/48kHz (normal-
speed) and 64/88.2/96kHz (high-speed) input
sampling frequencies
• ON/OFF control
Digital attenuator
• 128-step attenuation using linear 7-bit data set-
ting
Soft muting
• 1016/fs (normal-speed sampling)
• 2032/fs (high-speed sampling)
Output data round-off operation (normal round-off
or rectangular distribution dither round-off)
Selectable LR clock polarity
Microprocessor controllable
Input data format
• 2s complement, MSB first, alternating L/R
serial
• 16/20/24/32-bit data selectable
Output data format
• 2s complement, MSB first, simultaneous L/R
serial
• 20/24-bit data selectable.
24-bit internal data processing
Jitter-free mode/synchronous mode selectable
Crystal oscillator circuit built-in
TTL-compatible outputs
Molybdenum-gate CMOS
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Interpolation filter (linear 3-stage FIR filter)
• Normal-speed sampling mode
1st stage (fs to 2fs) 121st order
2nd stage (2fs to 4fs) 21st order
3rd stage (4fs to 8fs) 13th order
• High-speed sampling mode
1st stage (fs to 2fs) 177th order
2nd stage (2fs to 4fs) 29th order
3rd stage (4fs to 8fs) 17th order
Deemphasis filter (IIR filter)
Arithmetic units
• 25
×
24-bit parallel adder
• 32-bit accumulator
Overflow limiter built-in
APPLICATIONS
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Digital audio equipment
ORDERING INFOMATION
Device
SM5846AP
Package
28-pin DIP
SEIKO NPC CORPORATION —1
SM5846AP
FILTER CHARACTERISTICS
Normal-speed Sampling
Parameter
Passband bandwidth
Stopband bandwidth
Passband ripple
Stopband attenuation
Group delay time
1
Rating
0 to 0.4535fs
0.5465 to 7.4535fs
±0.0004dB
≥
75dB
When CKS is HIGH: 63.89/fs (when SYNC is LOW) and 63.51/fs to 64.26/fs (when SYNC is HIGH)
When CKS is LOW: 63.76/fs (when SYNC is LOW) and 63.59/fs to 64.14/fs (when SYNC is HIGH)
1. The time difference due to digital filter operation between the end of serial data input (at rate fs) and the start of serial data output (at rate 8fs).
Overall frequency characteristic
0
20
Attenuation [dB]
40
60
80
100
120
140
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Frequency [fs]
Passband frequency characteristic
−0.0005
Attenuation [dB]
−0.00025
0.00000
0.00025
0.0005
0.000
0.125
0.250
0.375
0.500
Frequency [fs]
Transition band characteristic
0
20
40
60
80
100
120
140
0.00
0.125
0.25
0.375
0.50
0.625
0.75
0.825
1.00
Attenuation [dB]
Frequency [fs]
SEIKO NPC CORPORATION —3
SM5846AP
High-speed Sampling (8fs Output)
Parameter
Passband bandwidth
Stopband bandwidth
Passband ripple
Stopband attenuation
Group delay time
1
Rating
0 to 0.4535fs
0.5465 to 7.4535fs
±0.00001dB
≥
105dB
When CKS is HIGH: 51.91/fs (when SYNC is LOW) and 51.53/fs to 52.28/fs (when SYNC is HIGH)
When CKS is LOW: 51.78/fs (when SYNC is LOW) and 51.40/fs to 52.15/fs (when SYNC is HIGH)
1. The time difference due to digital filter operation between the end of serial data input (at rate fs) and the start of serial data output (at rate 8fs).
Overall frequency characteristic
0
20
40
60
80
100
120
140
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Passband frequency characteristic
Transition band characteristic
SEIKO NPC CORPORATION —4
瑞萨MCU/MPU
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