FlexRay Active Star Coupler – 4 Branch

Product Details

Block Diagram

TJA1085 Block Diagram

TJA1085 Block Diagram



  • 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


  • 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 VIO, VCC, VBUF and VBAT
  • Auto I/O level adaptation to host controller supply voltage VIO
  • 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)


  • 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 VIO or VCC 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

Part numbers include: TJA1085HN.


Quick reference to our documentation types.

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