OVERVIEW

The SM5843A×1 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), digital deemphasis and soft muting functions. It accepts 16, 18, or 20-bit input data, and outputs data in 18 or 20-bit format. It operates using either a 384fs or 256fs system clock.

FEATURES

■ Filter configuration (2-channel processing)

   • 8-times oversampling (interpolation)

      - 3-stage FIR configuration

   • Deemphasis filter

      - IIR filter configuration for correct gain and phase characteristics

      - 2-channel independent ON/OFF control

      - 32/44.1/48 kHz sampling frequency (fs)

   • 21 × 22-bit parallel multiplier/25-bit accumulator for high precision

   • Overflow limiter

■ 2 oversampling filter characteristics

   • Sharp roll-off characteristic (response 1)

      - ≤ ±0.00005 dB passband ripple (0 to 0.4535fs)

      - ≥ 110 dB stopband attenuation (0.5465fs to 7.4535fs)

   • Slow roll-off characteristic (response 2)

      - ≤ ±0.00003 dB passband ripple (0 to 0.235fs)

      - ≥ 77 dB stopband attenuation (0.745fs to 7.255fs)

■ Soft muting

■ Digital attenuator

■ Input data format

   • 2s complement, MSB first

      - LR alternating, 16/18/20-bit serial, trailing data

      - LR alternating, 20-bit serial, leading data

      - LR simultaneous, 20-bit serial, leading data

■ Output data format

   • 2s complement, MSB first, LR simultaneous

   • 18/20-bit serial

   • BCKO burst (NPC format)

■ Dither processing ON/OFF control

■ Jitter-free/Sync mode selectable

■ 256fs/384fs system clock selectable

   • 21.2/14.2MHz maximum frequency (384fs/256fs)

■ 5 V supply

■ Crystal oscillator circuit built-in

■ TTL-compatible input/outputs

■ 28-pin plastic DIP and SOP

■ Molybdenum-gate CMOS

APPLICATIONS

■ CD players

■ DAT players

■ PCM systems