Infineon TLE7258SJ LIN Transceiver: Key Features and Application Design Considerations
The Infineon TLE7258SJ is a highly integrated, monolithic LIN (Local Interconnect Network) transceiver designed to interface between a LIN protocol controller and the physical bus in automotive networks. As a cornerstone for in-vehicle sub-networks, it enables reliable communication for sensors and actuators in body control, comfort electronics, and powertrain applications. Its design prioritizes robustness, low power consumption, and ease of integration, making it a preferred choice for automotive engineers.
Key Features of the TLE7258SJ
The device's architecture is built around several defining characteristics that ensure superior performance in harsh automotive environments.
Robust ESD and EMI Performance: The TLE7258SJ boasts excellent Electrostatic Discharge (ESD) protection, exceeding ±8 kV (IEC 61000-4-2) on the LIN bus pin. This inherent ruggedness safeguards the device and the host microcontroller from transient events during production and vehicle operation. Furthermore, its high electromagnetic immunity (EMI) ensures stable data communication even when situated close to high-power sources like motors or solenoids.
Very Low Power Consumption: A standout feature is its ultra-low current consumption in low-power sleep mode, typically drawing less than 10 µA. This is critical for modern vehicles, where minimizing quiescent current is essential to prevent battery drain when the car is parked for extended periods. It can be seamlessly woken up either by a local wake-up via the LIN protocol controller or by a remote wake-up signal via the LIN bus.
Integrated Voltage Regulator: The chip includes a 5V/50mA linear voltage regulator that can power an external microcontroller or a sensor. This integration reduces the total system component count, simplifies the power supply design, saves board space, and lowers the overall Bill of Materials (BOM) cost.
Compliance and Diagnostic Features: The transceiver is fully compliant with the LIN 2.x, SAE J2602, and ISO 17987 standards, ensuring interoperability within any LIN network. It also provides valuable diagnostic capabilities, such as thermal shutdown and detection of a loss of battery supply (VBAT), enhancing system safety and reliability.
Application Design Considerations
Successfully implementing the TLE7258SJ requires careful attention to several design aspects to achieve optimal network performance and reliability.
1. Bus Termination and Biasing: A proper LIN bus requires a pull-up resistor (typically 1 kΩ) and a series resistor (typically 470 Ω) at the master node. The slave nodes, where the TLE7258SJ is often used, should not have this termination. Correct biasing is essential for ensuring proper signal slope control and minimizing reflections.
2. Electromagnetic Compatibility (EMC): To meet stringent automotive EMC requirements, a series resistor (e.g., 47 Ω) and a capacitor to ground (e.g., 2.2 nF to 10 nF) are recommended close to the LIN bus pin. This simple RC filter helps suppress high-frequency noise without significantly distorting the LIN signal.
3. Power Supply Decoupling: Stable operation mandates effective power supply decoupling. A 100 nF ceramic capacitor should be placed as close as possible to the VBAT pin and the VSUP pin (if the internal regulator is used) to ground. This mitigates noise on the supply line and ensures stable internal operation.
4. Thermal Management: Although the device features thermal shutdown protection, the PCB layout must provide adequate copper area for the exposed ground pad (DDPAK package) to dissipate heat efficiently, especially if the internal voltage regulator is supplying near its maximum current.
5. Wake-up Source Management: The system software must correctly handle the wake-up and sleep routines. Understanding the difference between local and remote wake-up events is crucial for designing a network that responds correctly to user input while maintaining its ultra-low quiescent current profile.
In summary, the Infineon TLE7258SJ stands out as an exceptionally robust and feature-rich LIN transceiver that simplifies design while meeting the rigorous demands of the automotive environment. Its integrated regulator, ultra-low sleep current, and superior protection features make it an ideal solution for creating reliable and cost-effective LIN slave nodes, solidifying its position as a key component in modern vehicle networking.
Keywords: LIN Transceiver, Automotive Networking, Low Power Consumption, ESD Protection, Integrated Voltage Regulator
