Cirrus Logic AN301 User Manual
An301, Introduction
Copyright
© Cirrus Logic, Inc. 2006
(All Rights Reserved)
Time Division Multiplexed Audio Interface:
A Tutorial
INTRODUCTION
Transferring multiple channels of digital audio data within an audio product can be a challenge. The complexities
involving signal routing and providing a sufficient number of input/output ports on digital-signal-processors and con-
verters can be a daunting task. As a result, the industry has adopted a Time Division Multiplexed (TDM) interface
that allows multiple channels of data to be transmitted on a single data line. The TDM interface is by far the most
common mechanism used to transfer multiple channels of audio data between devices within a system as shown in
The TDM interface has not been standardized and there can be variants between the TDM formats. For-
tunately the TDM ports in DSP devices are programmable and will support the multitude of options.
It is advantageous to limit the degrees of flexibility in a TDM interface for analog-to-digital converters, digital-to-an-
alog converters, multiple function audio CODECs and other high-performance mixed-signal products to avoid po-
tential performance degradation due to clock interference. As a result, Cirrus Logic has chosen to standardize on a
TDM format for audio converter products and support a subset of the options that are available with DSP devices,
including the DSP products from Cirrus Logic. The goal of this document is to present an overview of the TDM in-
terface and a discussion of the TDM format that is supported in Cirrus Logic audio converter products.
Figure 1. TDM System Block Diagram
Multi-Channel
Analog-to-Digital Converter
Multi-Channel
Digital-to-Analog Converter
DSP
Frame Sync
Serial Clock
Serial Data
Serial Data
SEPTEMBER
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AN301REV1
AN301