Document
SM5842AP/APT
NIPPON PRECISION CIRCUITS INC.
High-Class Audio Multi-function Digital Filter
OVERVIEW
The SM5842AP/APT is a multi-function digital filter IC, fabricated using NPC’s Molybdenum-gate CMOS process, for digital audio reproduction equipment. It features 8-times oversampling (interpolation), independent left and right-channel digital deemphasis, and soft muting functions. It accepts 16, 18, 20 or 24-bit input data, and outputs data in 18, 20, 22 or 24-bit format. It operates using either a 384fs or 256fs system clock at sampling frequencies up to 48 kHz + 10% (384fs SM5842AP, 384/256fs SM5842APT).
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• 256fs - 13 MHz maximum frequency (at maximum fs = 50.7 kHz, SM5842AP) - 14.2 MHz maximum frequency (at maximum fs = 55.2 kHz, SM5842APT) Crystal oscillator circuit built-in TTL-compatible input/outputs 5.0 ± 0.25 V supply Molybdenum-gate CMOS process 28-pin plastic DIP
Filter Configuration
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FEATURES
Functions
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L/R 2-channel processing 8-times oversampling (interpolation) • ≤ ±0.00002 dB passband ripple • ≥ 117 dB stopband attenuation Digital deemphasis • 32/44.1/48 kHz sampling frequency (fs) • 2-channel independent ON/OFF control Soft muting • 2-channel independent ON/OFF control Input data format • 2s complement, MSB first - LR alternating, 16/18/20/24-bit serial, trailing data - LR alternating, 24-bit serial, leading data - LR simultaneous, 24-bit serial, leading data Output data format • 2s complement, MSB first, LR simultaneous • 18/20/22/24-bit serial • BCKO burst (NPC format) Dither round-up processing • ON (dither rounding)/OFF (normal rounding) control 25-bit internal data length Jitter-free function for correct operation in the presence of jitter between the system clock and LRCI clock • ON (jitter-free mode)/OFF (sync mode) control 256fs/384fs system clock selectable • 384fs - 21.2 MHz maximum frequency (at maximum fs = 55.2 kHz)
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Linear phase 3-stage FIR interpolation filter • 169-tap 1st stage (fs to 2fs) • 29-tap 2nd stage (2fs to 4fs) • 17-tap 3rd stage (4fs to 8fs) Deemphasis filter - IIR filter configuration for accurate gain and phase characteristics 26 × 24-bit parallel multiplier/32-bit accumulator for high precision Overflow limiter built-in
APPLICATIONS
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CD players DAT players PCM systems
PINOUT
DI / INF2N BCKI CKSLN INF1N IW1N / DIL XTI XTO VSS CKO IW2N / DIR OW1N OW2N SYNCN RSTN
1
28
LRCI DG BCKO WCKO DOL DOR VDD DITHN MUTEL MUTER FSEL2 FSEL1 DEMPL
SM5842AP/APT
14 15
DEMPR
NIPPON PRECISION CIRCUITS—1
SM5842AP/APT
PACKAGE DIMENSIONS
Unit: mm
28-pin plastic DIP
0° to 15° 13.8 0.2 + 0.3 1.5 − 0.05 3.8 0.1
BLOCK DIAGRAM
CKSLN LRCI DI / INF2N BCKI IW1N / DIL IW2N / DIR
XTI XTO CKO
System Clock
3.2 0.2 7.7 0.5
2.54
0.45 0.1
4.5 0.3
+ 0.25− 0.10 0.05
37.3 0.3
15.2
Input Data Interface
INF1N
RSTN SYNCN
Timing Controller
Filter and Attenuation Arithmetic block
DITHN
DEMPL DEMPR FSEL1 FSEL2 Deemphasis Control Output Data Interface OW2N MUTEL MUTER Mute Co.