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). FEATURES Functions ■ 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) • 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 ■ 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 ■ CD players ■ DAT players ■ PCM systems
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