AD2428W datasheet(3/38 Pages) AD

3 / 38 page

AD2420(W)/AD2426(W)/AD2427(W)/AD2428(W)/AD2429(W)

Rev. B

Page 3 of 38

January 2020

GENERAL DESCRIPTION

The Automotive Audio Bus (A2B

®) provides a multichannel,

I2S/TDM link over distances of up to 15 m between nodes. It

embeds bidirectional synchronous pulse-code modulation

(PCM) data (for example, digital audio), clock, and synchroni-

zation signals onto a single differential wire pair. A2B supports a

direct point to point connection and allows multiple, daisy-

chained nodes at different locations to contribute and/or con-

sume time division multiplexed (TDM) channel content.

A2B is a single-master, multiple-slave system where the trans-

ceiver at the host controller is the master. The master generates

clock, synchronization, and framing for all slave nodes. The

master A2B transceiver is programmable over a control port

(I2C) for configuration and read back. An extension of the con-

trol port protocol is embedded in the A2B data stream, which

grants direct access of registers and status information on slave

transceivers as well as I2C to I2C communication over distance.

The transceiver can connect directly to general-purpose digital

signal processors (DSPs), field-programmable gate arrays

(FPGAs), application specific integrated circuits (ASICs),

microphones, analog-to-digital converters (ADCs), digital-to-

analog converters (DACs), and codecs through a multichannel

I2S/TDM interface. It also provides a pulse density modulation

(PDM) interface for direct connection of up to four PDM digital

microphones.

Finally, the transceiver also supports an A2B bus powering fea-

ture, where the master node supplies voltage and current to the

slave nodes over the same daisy-chained, twisted pair wire cable

as used for the communication link.

Table 1. Product Comparison Guide

Feature

AD2420/



AD2420W

AD2426/



AD2426W

AD2427/



AD2427W

AD2428/



AD2428W

AD2429/



AD2429W

Master capable

Yes

Number of slaves discoverable1

N/A

Up to 10

Up to 2

Functional TRX blocks

A only

A + B

B only

2S/TDM support

Yes

PDM microphone inputs

2 mics

4 mics

Max node to node cable length

5 m

15 m

5 m

1 N/A means not applicable.

2 PDM microphones must be connected to the DRX0/IO5 pin.

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