UJA1078ATW/3V3/1J

Specialized Overview

The UJA1078ATW/3V3/1J is a high-speed CAN and dual LIN core System Basis Chip (SBC) from NXP Semiconductors. It integrates a high-speed CAN transceiver compliant with ISO 11898-2:2003 and ISO 11898-5:2006, two LIN transceivers supporting LIN 2.0 through 2.2A, and an advanced independent watchdog. The device features a scalable 3.3 V main voltage regulator (V1) delivering up to 250 mA for microcontroller supply, extendable via an external PNP transistor. A separate 5 V voltage regulator (V2) powers the on-board CAN transceiver. Communication with the host microcontroller occurs via a full-duplex 16-bit Serial Peripheral Interface (SPI).

Specialized Feature Summary

• Integrates high-speed CAN and dual LIN transceivers with enhanced EMC performance and robust transient protection.
• Features a scalable 3.3 V main voltage regulator capable of 250 mA output, with options for external heat distribution.
• Includes an advanced programmable watchdog with Window and Timeout modes supported by an on-chip oscillator.
• Provides detailed system status reporting and control via a 16-bit SPI interface for configuration and diagnosis.

Specialized Applications

• Electronic Control Units (ECU) requiring integrated power management and networking interfaces.
• Automotive applications utilizing high-speed CAN as the main network interface.
• Systems employing LIN interfaces as local sub-busses for sensor and peripheral control.

Specialized Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm regulatory compliance and package variations. Confirm that the component meets all applicable automotive standards required for your specific design implementation before finalizing procurement.

Specialized Selection Notes

Select this variant when a fixed 3.3 V output is required for the microcontroller supply. Ensure the application benefits from the integrated watchdog functionality if safety-critical monitoring is necessary. Verify that the HTSSOP32 package dimensions align with the PCB layout constraints.

Specialized Part Context

This component belongs to the UJA1078A family of core System Basis Chips designed to replace discrete components in Electronic Control Units. The family includes variants with different voltage regulator outputs and optional watchdog features, providing flexibility for various automotive networking architectures.

Specialized Replacement Considerations

The datasheet notes interoperability and downward compatibility with the TJA1042 CAN transceiver. However, direct replacement requires verifying pinout compatibility and ensuring the target system supports the integrated SBC architecture rather than a standalone transceiver.

Specialized FAQ

What is the function of the WDOFF pin?

The WDOFF pin is used to deactivate the watchdog. When driven HIGH, it disables the watchdog and results in a software reset.

How does the device handle overtemperature conditions?

If the chip temperature exceeds the activation threshold, the SBC enters Overtemp mode, switching off voltage regulators and driving the LIMP pin LOW to activate limp home hardware.

Can the main voltage regulator be extended for higher current?

Yes, the V1 regulator can be combined with an external PNP transistor to increase current capability and improve heat distribution across the PCB.