Cirrus Logic CRD5381 - Manual (Page 2)

2 DS563RD1
CRD5381
Description
The combination of the CS5381 Analog-to-Digital Converter and CS8421 Asynchronous Sample Rate Converter
creates an analog-to-digital conversion system with an asynchronous digital decimation filter that is virtually
immune to interface or network jitter. In addition, the CS8421 adds a multi-channel Time Division Multiplexed
(TDM) output format option. These unique features address many of the issues and design challenges associated
with networked audio systems and other high-performance applications. In addition to the standard 24-bit audio
data, the CS8421 adds the functionality to output properly dithered 32, 20, or 16-bit data.
The CRD5381 was designed as a platform for easy evaluation of the jitter rejection, sample rate conversion, and
time-division multiplexing capabilities of the CS8421 in the context of a A/D conversion system with an asynchro-
nous decimation filter. The CRD5381 accepts four channels of balanced, analog audio input and provides four
channels of PCM data output. The data output can be either a four-channel TDM format or two independent stereo
left-justified data outputs. The PCM data output is synchronous to the serial left-right clock and bit clock that the user
supplies. The CRD5381 also provides status indicators including ADC overflow and SRC unlock, and it accepts an
external reset signal. The only system power requirements for the design include +/- 12 Volts and +3.3 Volts. The
required input signals are a left/right or word clock and serial clock for the audio data output.
This document includes operational instructions and schematics for the CRD5381 and is a companion document to
the Cirrus Logic applications note AN270, “Audio A/D conversion with Asynchronous Decimation Filter” [1]. Please
also refer to the CS5381 and CS8421 data sheets for specific product information and specifications [2,3]. Both doc-
uments, as well as AN270, are available online at http://www.cirrus.com
The CRD5381 schematic set is shown in Figures 9 through 14 and the board layout is shown in Figures 15
through 19 . A block diagram of the CRD5381 is shown in Figure 8 .
ORDERING INFORMATION
Product Description Order#
CRD5381 Audio A/D Converter w/ Asynchronous Decimation Filter Reference Design CRD5381