Document
Automotive Audio Bus A2B Transceiver
AD2420(W)/AD2426(W)/AD2427(W)/AD2428(W)/AD2429(W)
A2B BUS FEATURES
Line topology Single master, multiple slave Up to 15 m between nodes and up to 40 m overall cable length (see Table 9)
Communication over distance Synchronous data Multichannel I2S/TDM to I2S/TDM Synchronous clock, phase aligned in all nodes Low latency slave to slave communication Control and status information I2C to I2C GPIO and interrupt
Bus power or local power slave nodes Configurable with SigmaStudio graphical software tool AEC-Q100 qualified for automotive applications
A2B TRANSCEIVER FEATURES
Configurable A2B bus master or slave operation I2C interface 8-bit to 32-bit multichannel I2S/TDM interface
Programmable I2S/TDM data rate Up to 32 upstream and 32 downstream channels PDM interface Programmable PDM clock rate Up to 4 high dynamic range microphone inputs Simultaneous reception of I2S data with up to 4 PDM microphones Unique ID register for each transceiver Crossover or straight-through cabling Programmable settings to optimize EMC performance
APPLICATIONS
Audio communication link Microphone arrays
Beamforming Hands free and in car communication Active and road noise cancellation Audio/video conferencing systems
IOVDD DVDD PLLVDD
SCL
SDA
IRQ/IO0
I2C
ADR1/IO1
ADR2/IO2
PLL
DTX0/IO3 DTX1/IO4 DRX0/IO5 DRX1/IO6
I2S/TDM PDM
PDMCLK/IO7
BCLK SYNC
VOUT1 VIN VOUT2
VREG1
VREG2
VSSN
VSS
BTRXVDD
A2B TRX B (Towards Last Slave)
DIAGNOSTICS
A2B TRX A (Towards Master)
ATRXVDD
BP BCM BN
SWP SENSE
AP ACM AN
Figure 1. Functional Block Diagram
A2B and the A2B logo are registered trademarks of Analog Devices, Inc.
Rev. C
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AD2420(W)/AD2426(W)/AD2427(W)/AD2428(W)/AD2429(W)
TABLE OF CONTENTS
A2B Bus Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A2B Transceiver Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
A2B Bus Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 I2S/TDM Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Pulse Density Modulation (PDM) Interface . . . . . . . . . . . . . . . . . 6 GPIO Over Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Mailboxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Data Slot Exchange Between Slaves . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Clock Sustain State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Programmable Settings to Optimize EMC
Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Power Supply Rejection Ratio (PSRR) . . . . . . . . . . . . . . . . . . . . . . 11 Timing Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Power-Up Sequencing Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . 16 A2B Bus System Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 PDM Typical Performance Characteristics . . . . . . . .