The AN‑394 application note explains a three‑board outboard DAC that receives AES/EBU digital audio, converts the sample rate with an AD1891 asynchronous sample‑rate converter, and outputs analog audio via an AD1862 DAC. The design uses an ADSP‑2115 DSP for interpolation and FIR filtering, and separates analog and digital sections to minimize noise and jitter.
Key features include a fixed 48 kHz output sample rate, support for input rates from 24 kSPS to 48 kSPS, a polyphase filter bank with <0.01 dB passband ripple, >110 dB stopband attenuation, and a dynamic range of 96 dB. The document provides block diagrams, circuit schematics, and performance graphs for engineers designing high‑quality audio conversion systems.
| Supported input sample rate | 24 kSPS – 48 kSPS |
|---|---|
| Fixed output sample rate | 48 kHz |
| Passband ripple (polyphase filters) | < 0.01 dB |
It accepts AES/EBU audio with sample rates ranging from 24 kSPS to 48 kSPS.
The converter outputs audio at a fixed 48 kHz sample rate.