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