NXP TJA1051T/118 CAN Transceiver: Datasheet, Application Circuit, and Key Features
The NXP TJA1051T/118 is a high-speed CAN transceiver that serves as the critical interface between a controller area network (CAN) protocol controller and the physical two-wire CAN bus. Complying with the ISO 11898 standard, it is designed for high-speed automotive and industrial applications, offering robust performance and enhanced electromagnetic compatibility (EMC).
Key Features
The TJA1051T/118 boasts a set of features that make it a preferred choice for designers:
High-Speed Operation: Supports data rates of up to 1 Mbaud, making it suitable for real-time control networks.
Excellent EMC Performance: Features a low electromagnetic emission and high electromagnetic immunity, minimizing the need for additional common-mode chokes in many applications.
Power Management: Includes very low-current standby and sleep modes with bus wake-up capability, which is crucial for power-sensitive applications like automotive nodes to minimize quiescent current when the bus is idle.
Robustness: Integrated overvoltage protection on the CAN bus pins (CANH and CANL) and high resistance to transients as specified by automotive standards.
Thermal Protection: An overtemperature protection mechanism shuts down the device to prevent damage under fault conditions.
Fail-Safe Features: Guarantees a logic high output on the receiver (RXD) pin in case of a bus short-circuit or if the bus is idle.
Application Circuit
Implementing the TJA1051T/118 is straightforward. A typical application circuit involves a few key external components:
1. Microcontroller Connection: The TXD pin connects to the transmit pin of the CAN controller, while the RXD pin connects to the receive pin. The STB (Standby) pin allows the microcontroller to place the transceiver into its low-power mode.
2. Power Supply: A 5V ±4% supply is connected to the VCC pin. A 100nF ceramic decoupling capacitor must be placed as close as possible to the VCC and GND pins to filter high-frequency noise.
3. CAN Bus Connection: The CANH and CANL pins connect directly to the CAN bus. A common-mode choke (optional for improved EMC) and series resistors (typically 0-10Ω) can be added in series with each line to suppress high-frequency oscillations.
4. Termination: The CAN bus must be terminated at both ends with a 120Ω resistor between CANH and CANL to match the characteristic impedance of the bus cable and prevent signal reflections.
Datasheet Overview
The official datasheet is the ultimate source of information. Key sections to review include:
Absolute Maximum Ratings: The limits for voltage, current, and temperature that must not be exceeded.
DC and AC Electrical Characteristics: Detailed specifications for supply current, output levels, timing parameters (e.g., loop delay), and input thresholds.
Functional Description: Explains the behavior of the device in normal, standby, and sleep modes.
Application Information: Provides detailed guidance on PCB layout (e.g., using a ground plane, keeping the high-speed traces short), component selection, and EMC optimization.
The NXP TJA1051T/118 is a highly reliable and efficient CAN transceiver that forms the backbone of robust network communication in demanding environments. Its exceptional EMC characteristics, integrated protection features, and low-power management capabilities make it an outstanding solution for modern automotive and industrial control systems.
Keywords:
CAN Transceiver, ISO 11898, EMC Performance, Low-Power Mode, Automotive Applications
