TJA1085: FlexRay Active Star Coupler – 4 Branch

Overview

The TJA1085 is a FlexRay active star coupler that can connect up to 4 branches of a FlexRay network. The TJA1085 is compliant with the FlexRay electrical physical layer specification V3.0.1/ISO17458-4

Several TJA1085 devices can be connected via their TRXD0/1 interfaces to increase the number of branches in the network. A dedicated Communication Controller (CC) interface allows for integration into an ECU. The TJA1085 supports low-power management by offering bus wake-up capability along with battery supply and voltage regulator control. The TJA1085 meets industry standards for EMC/ESD performance and provides enhanced bus error detection, low current consumption and unmatched asymmetric delay performance.

The TJA1085 also fulfills the JASPAR requirements as defined by the Japanese car industry.

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Features

General

Fulfills JASPAR requirements
Automotive product qualification in accordance with AEC-Q100
Data transfer rates from 2.5 Mbit/s to 10 Mbit/s
Supports 60 ns minimum bit time at 400 mV differential voltage
Low-power management for battery-supplied ECUs
Very low current consumption in AS_Sleep mode
Leadless HVQFN44 package with improved Automated Optical Inspection (AOI) capability

Functional

Supports autonomous active star operation independent of the host ensuring the TJA1085 remains active even if the host fails or is switched off
Branches can be independently configured
Branch extension via TRXD0/1 inner star interface
16-bit bidirectional SPI interface up to 2 Mbit/s for host communication
Full host control over branch status
Enhanced wake-up capability:
- Remote wake-up via wake-up pattern and dedicated FlexRay data frames
- Local wake-up via pin LWU
- Wake-up source recognition
- Configurable per branch
Enhanced supply voltage monitoring on V_IO, V_CC, V_BUFand V_BAT
Auto I/O level adaptation to host controller supply voltage V_IO
Can be used in 14 V, 24 V and 48 V powered systems
Enhanced bus error detection - detects short-circuit conditions on the bus
Instant transmitter shut-down interface (BGE pin)
Selective branch shut-down (partial networking)

Robustness

Bus pins protected against ±8 kV ESD pulses according to HBM and ±6 kV ESD pulses according to IEC61000-4-2
All pins protected against ±1000 V ESD according to CDM
All pins protected against ±200 V ESD according to MM
No reverse currents from the digital input pins to V_IO or V_CC when the TJA1085 is not powered up
Bus pins short-circuit proof to battery voltage (14 V, 24 V or 48 V) and ground
Overtemperature detection and protection
Bus pins protected against transients in automotive environment (according to ISO 7637 class C)

Active star functional classes

Active star - communication controller interface
Active star - bus guardian interface
Active star - voltage regulator control
Active star - logic level adaptation
Active star - host interface
Active star - increased voltage amplitude transmitter