TJA1085HN - 4-Branch FlexRay Active Star Coupler | NXP
MPN: TJA1085HN ✗ End of LifeTJA1085HN Overview
A FlexRay active star coupler is a network interface component that distributes communication among multiple FlexRay branches through an active, centrally located topology. Unlike a passive star point, an active star coupler contains controlled interface circuitry that supports a FlexRay network with up to four connected branches. It belongs to the hierarchy of FlexRay interface ICs, network transceivers, interface ICs, and integrated semiconductors.
The principal application feature is support for four FlexRay branches. The TJA1085HN operates from a 4.75 V supply and is listed with a maximum operating voltage of 60 V. Its automotive temperature grade, no-lead surface-mount construction, and square 44-terminal HVQFN package are suited to space-constrained vehicle electronic systems. The HVQCCN package designation identifies a 44-terminal, no-lead automotive package.
The TJA1085HN is compliant with FlexRay electrical physical layer specification V3.0.1 and ISO 17458-4. These standards define the physical-layer behavior used by FlexRay communication systems, including signaling requirements for reliable in-vehicle data exchange. Compliance makes the device relevant to central communication nodes that must distribute signals among multiple vehicle network branches rather than merely terminate a single bus.
Typical uses include automotive body and chassis controllers, powertrain control units, gateway modules, domain controllers, and centralized vehicle network nodes. The active-star topology is particularly useful where one controller must communicate through several independently routed branches while maintaining a defined FlexRay physical-layer implementation.
For a new design, evaluate the TJA1085G recommended by NXP before committing to the TJA1085HN. NXP states that the TJA1085HN is not covered by its longevity program’s production-continuity guarantee. Existing automotive programs may therefore need a deliberate sourcing and migration plan, including validation of the recommended device against the original electrical and PCB requirements.
This page consolidates the manufacturer’s device position, package information, standard references, sourcing implications, design guidance, and application guidance into a practical engineering overview. It helps designers distinguish protocol functionality, network topology, package constraints, and lifecycle considerations rather than treating the TJA1085HN as a generic four-port transceiver.
Drop-in alternatives for TJA1085HN — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
No drop-in alternatives available for this product.
Request AlternativesTJA1085HN Specifications
| Device Type | FlexRay active star coupler |
| Maximum Branch Count | 4 branches |
| Minimum Supply Voltage | 4.75 V |
| Maximum Operating Voltage | 60 V |
| FlexRay Physical Layer Compliance | V3.0.1 |
| International Standard | ISO 17458-4 |
| Package | 44-pin HVQFN (9 x 9 mm) |
| Package Code | HVQCCN |
| Package Shape | Square |
| Terminal Count | 44 terminals |
| Terminal Form | No lead |
| Mounting Type | Surface mount |
| Temperature Grade | Automotive |
TJA1085HN square Pin Configuration Guide
Pin configuration for TJA1085HN (square package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for TJA1085HN.
Refer to the datasheet for full pin configuration.
Typical Applications
TJA1085HN is suitable for 6 applications: Automotive Body Control Gateway, Powertrain Control Network, Vehicle Domain Controller, Chassis and Safety Controller, Automotive Communication Test Module, Legacy Vehicle Platform Maintenance.
Automotive Body Control Gateway
The TJA1085HN fits a centralized body or gateway controller that must distribute communication across as many as four FlexRay branches. Its active-star-coupler function is more appropriate than a passive star point when the system requires controlled participation in the FlexRay physical layer. The device complies with FlexRay physical-layer V3.0.1 and ISO 17458-4, while its 4.75 V minimum supply supports integration into conventional automotive electronics. The 44-pin HVQFN package limits board area but requires careful escape routing and thermal-aware placement. Because NXP does not guarantee production continuity for this MPN, engineers should plan lifecycle verification before committing a new vehicle platform.
Recommended
Powertrain Control Network
A powertrain control unit can use the TJA1085HN as the central active interface for up to four FlexRay network branches. The four-branch capability allows one controller to serve multiple distributed subsystems while preserving a defined FlexRay physical-layer implementation. Compliance with V3.0.1 and ISO 17458-4 supports design alignment with automotive network standards, and the 4.75 V minimum operating voltage suits integration with vehicle power systems. Engineers must follow the manufacturer datasheet for decoupling, branch termination, and exposed-pad thermal implementation. The automotive-grade package designation supports harsh-environment deployment, but application-specific qualification remains part of the system validation process.
Recommended
Vehicle Domain Controller
The TJA1085HN can serve as an active star coupler inside a vehicle domain controller when the controller must distribute FlexRay communication to four routed branches. This topology is useful during platform transitions where centralized compute connects legacy distributed subsystems. The device provides a dedicated active coupling function rather than requiring the controller to emulate the network through unrelated transceiver circuitry. Its 9 x 9 mm HVQFN construction supports compact integration, although the 44-terminal footprint demands disciplined escape routing. Designers should evaluate the recommended TJA1085G for new controller platforms and verify whether its package permits reuse of the existing PCB footprint.
Recommended
Chassis and Safety Controller
In a chassis or safety controller, the TJA1085HN can provide the active connection point for up to four FlexRay branches carrying time-sensitive vehicle data. Its standards-based physical-layer compliance is valuable when the controller bridges multiple chassis subsystems and requires consistent branch behavior. The automotive-grade, no-lead HVQFN package is suitable for compact control units, while the manufacturer datasheet remains the reference for pin-level routing and operating limits. Because production continuity is not guaranteed for the TJA1085HN, safety-related programs should establish whether the device is acceptable under their specific change-control and sourcing policies.
Recommended
Automotive Communication Test Module
The TJA1085HN is suitable for an automotive communication test module intended to emulate an active four-branch FlexRay node. Its defined role as an active star coupler allows a test system to investigate branch signaling in a controlled harness while maintaining compatibility with FlexRay physical-layer V3.0.1 and ISO 17458-4. The 4.75 V minimum operating voltage supports integration into vehicle-powered test equipment, and the 44-pin HVQFN package can reduce board area. Laboratory systems must follow the manufacturer’s pin and layout guidance to prevent signal-integrity issues, particularly around branch connections and the package thermal pad.
Recommended
Legacy Vehicle Platform Maintenance
The TJA1085HN remains relevant to maintenance programs for an existing vehicle platform whose validated PCB uses the 44-pin HVQFN device. Reusing the established design can avoid disruptive changes to a qualified body, chassis, or gateway controller. NXP’s recommendation of the TJA1085G for new designs does not remove the need to support installed equipment, but it does make allocation and lifecycle planning essential. Maintenance engineers should document the exact ordering configuration, inspect incoming-device condition, and perform normal change-control review. A new board based on the same network architecture should evaluate the recommended part rather than assuming a direct footprint match.
Recommended
Recommended Products Summary
Engineering reference data for TJA1085HN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Brand | NXP Semiconductors |
| Package | 44-pin HVQFN (9 x 9 mm) |
| Device Type | FlexRay active star coupler |
| Maximum Branch Count | 4 branches |
| Minimum Supply Voltage | 4.75 V |
| Maximum Operating Voltage | 60 V |
| FlexRay Physical Layer | V3.0.1 |
| International Standard | ISO 17458-4 |
| Temperature Grade | Automotive |
| Production Continuity Guarantee | Not guaranteed by the NXP longevity program |
Key Differentiators
- Supports a four-branch active FlexRay topology (vs TJA1085G)
- Established 44-pin HVQFN integration for validated legacy platforms (vs TJA1085G)
- Clear distinction between legacy continuity and new-design support (vs TJA1085G)
Design Notes
Use the 44-pin HVQFN land pattern and pin table from the NXP manufacturer datasheet without reconstructing the footprint from the 9 x 9 mm body size alone. Route each FlexRay branch directly to its assigned device pins, keep the high-frequency branch paths short and symmetrical, and preserve the manufacturer’s recommended thermal-pad connection. Confirm courtyard, solder-mask, and paste details against the package drawing before releasing Gerber files.
FlexRay branch routing should minimize discontinuities, unnecessary stubs, and coupling between neighboring branches. Follow the manufacturer’s reference layout and component-placement guidance when available, and place branch-termination or damping components at locations that preserve controlled impedance. Because the TJA1085HN contains active interface circuitry, its layout must be evaluated as part of the complete network branch rather than as a generic point-to-point transceiver connection.
The 44-terminal HVQFN provides substantial electrical connectivity in a compact package, but its exposed thermal pad still requires an appropriate copper and via strategy. Follow the NXP datasheet for exposed-pad connection and thermal-layout requirements, keep the pad unobstructed by components where specified, and verify temperature rise under the vehicle’s worst-case ambient and network activity. Do not infer a junction-temperature limit or thermal resistance without the manufacturer’s package data.
Design the 4.75 V minimum operating supply with transient margin appropriate to the vehicle power environment. Place input and bypass capacitors close to the device’s supply and ground pins, using the capacitance and voltage ratings specified by the manufacturer. Review the 60 V maximum operating limit carefully when deriving protection from load dump or other automotive transients; it is an operating limit, not permission to exceed the application’s transient requirements.
Do not treat TJA1085G as a confirmed drop-in replacement merely because NXP recommends it for new designs. The available records do not establish a shared 44-pin HVQFN footprint, pin-for-pin function, identical electrical limits, or equivalent qualification between the two devices. Treat the change as a redesign with package, schematic, firmware-interface, EMC, and vehicle-validation reviews, especially in an existing safety-related platform.
Compliance Information
The device is identified as automotive grade and uses a no-lead package, but specific RoHS, REACH, AEC-Q100, lead-free, halogen-free, and conflict-minerals declarations were not identified in the available manufacturer summaries. The FlexRay V3.0.1 and ISO 17458-4 references describe interface compliance and are not substitutes for environmental or automotive qualification declarations.
