AD2426 datasheet(17/38 Pages) AD

17 / 38 page

AD2426/AD2427/AD2428

Rev. F

Page 17 of 38

November 2023

A2B BUS SYSTEM SPECIFICATION

Table 9. A2B System Specifications

Parameter

System Specification

Cable

Unshielded, single, twisted pair wire (UTP) with 100 Ω differential impedance.

Maximum Cable Length

System With a Mix of



AD240x/AD241x/AD242x/AD243x

Transceivers

Specification defined by the most restrictive data sheet.

System With Only



AD2426/AD2427/AD2428 Transceivers

80 m total, 15 m between nodes.

Maximum Number of Nodes

System With a Mix of



AD240x/AD241x/AD242x/AD243x



Transceivers

Specification defined by the most restrictive data sheet.

System With Only



AD2426/AD2427/AD2428 Transceivers

17 nodes (1 main node and 16 subordinate nodes).

Maximum Number of Audio Slots1

64 total, up to 32 upstream and 32 downstream slots, depending upon system design.

Number of Audio Channels per



Subordinate Node

Individually programmable 0 to 32 upstream channels and 0 to 32 downstream channels.

Synchronous A2B Data Slot Size

8, 12, 16, 20, 24, 28, or 32 bits to match I2S/TDM data-word lengths. Same slot size for all nodes.

Upstream and downstream can choose different slot sizes. 12-, 16-, or 20-bit slot sizes can carry

compressed data over the A

2B bus for 16-, 20-, or 24-bit I2S/TDM word lengths.

Audio Sampling Frequency

44.1 kHz to 48 kHz. All nodes sample synchronously. Subordinate node transceivers support sample

rates (fS) of 1× (48 kHz), 2× (96 kHz) or 4× (192 kHz), individually configured per subordinate.

To support 2× and 4× sampling rates in subordinates, the main transceiver uses two and four times

the number of I2S/TDM data channels as the 1× sampling frequency (fSYNCM) interface to the host.

Transceivers also support reduced rate sampling for 24 kHz, 12 kHz, 6 kHz, 4 kHz, 3 kHz, 2.4 kHz,



2 kHz, 1.71 kHz, or 1.5 kHz at a low latency 48 kHz superframe rate.

Discovery Time

Less than 35 ms per node. Much less than 560 ms for total system startup in a system with 16

subordinate nodes. Includes register initialization.

Maximum Bus Current per Node



Prior to Discovery Completion (IBUSDISC)

60 mA. Measured at the negative bias switch.

Maximum Total Bus Capacitance (CBUSDISC)70 μF.

Bit Error Detection

Robust error detection for control data and status data with 16-bit cyclic redundancy check (CRC).

Error Correction

Parity and line code error detection on synchronous data slots with audio error correction (repeat

of last known good data).

For 24-bit and 32-bit data channels, single error correction and double error detection (SECDED) of

synchronous data slots is possible.

Line Fault Diagnostics1

Location and cause of cable fault can be detected for A2B wires shorted to a high voltage (for

example, positive terminal of car battery), shorted to ground (for example, car chassis), wires

shorted to each other, wires reversed or open connection.

System EMI/EMC

Meets or exceeds industry specifications for robustness (ISO 11452-2, ISO 11452-4, ISO 7637-3) and

emissions (CISPR25).

System ESD Rating

Meets ISO 10605 severity levels.

1 See the AD2426/7/8 Automotive Audio Bus (A2B) Transceiver Technical Reference for more information.

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