NXP Semiconductors UJA1079ATW/3V3/WDJ

Overview

UJA1079ATW/3V3/WDJ from NXP Semiconductors is a LIN Core System Basis Chip (SBC) integrating a LIN 2.2A-compliant transceiver, 3.3 V ±2 % voltage regulator (250 mA), advanced window/timeout watchdog, SPI interface, dual local wake-up inputs, and limp home output - designed for automotive ECU power and communication management in body control modules and sensor nodes.

For engineers reviewing the UJA1079ATW/3V3/WDJ datasheet, UJA1079ATW/3V3/WDJ pinout, UJA1079ATW/3V3/WDJ application, or UJA1079ATW/3V3/WDJ equivalent, this page delivers verified functional scope, thermal-aware regulator behavior, LIN bus fault protection (±58 V short-circuit proof), ISO 7637-3 transient immunity, and watchdog timing modes critical for ASIL-B–aligned ECU designs.

Technical Context

The UJA1079ATW/3V3/WDJ implements a state-machine-based system controller managing Off, Standby, Normal, Sleep, and Overtemp modes with deterministic transitions triggered by VBAT thresholds, wake events, or temperature limits. Its LIN transceiver supports low-slope mode (10.4 kbit/s) for EMC optimization and includes integrated termination diode at DLIN.

Power management integrates V1 regulation with external PNP transistor support (via VEXCTRL/VEXCC), programmable current thresholds (50/85 mA activation/deactivation), and dual undervoltage detection (90 % or 70 % reset threshold). The watchdog uses an independent on-chip oscillator and supports Window, Timeout, and Off modes with configurable 8 ms to 4096 ms periods.

Key Specifications

Pinout & Package

Package: HTSSOP32 (SOT549-1), thermally enhanced thin shrink small outline package with 32 leads, 0.65 mm pitch, 6.1 mm body width, and exposed center pad soldered to PCB ground for optimal thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LIN system basis chip applications.

Compared with UJA1079ATW/3V3/WDJ, UJA1076ATW/3V3/WDJ reduces cost and complexity but sacrifices limp-home safety and high-current scalability, while TLE9183QK adds CAN FD and wider VBAT support at the expense of larger footprint and non-drop-in replacement.

Availability

UJA1079ATW/3V3/WDJ is available at Aetrix Electronics and suitable for automotive body electronics, door module production, and seat control systems requiring stable component supply, long-term lifecycle assurance, and AEC-Q100 Grade 1 qualification.

Supply support for UJA1079ATW/3V3/WDJ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in automotive-grade mixed-signal ICs and functional safety compliance.

The UJA1079ATW/3V3/WDJ belongs to NXP's LIN System Basis Chip product line, engineered specifically for ASIL-B–capable ECU power management, communication, and fail-safe control in body electronics and distributed sensor networks.

FAQ

What LIN protocol versions does the UJA1079ATW/3V3/WDJ support?

The UJA1079ATW/3V3/WDJ supports LIN 2.2A and SAE J2602, and is backward compatible with LIN 2.2, LIN 2.1, LIN 2.0, LIN 1.3, LIN 1.2, LIN 1.1, and LIN 1.0. This broad compatibility ensures seamless integration into legacy and next-generation automotive networks without protocol translation layers or firmware updates.

Does the UJA1079ATW/3V3/WDJ include a watchdog, and how is it configured?

Yes, the UJA1079ATW/3V3/WDJ includes an advanced independent watchdog with Window, Timeout, and Off modes. It is configured via the WMC bit in the WD_and_Status register and the WDOFF pin. The default period is 128 ms, adjustable from 8 ms to 4096 ms using the NWP bits. The watchdog uses an on-chip oscillator, ensuring operation even if V1 fails.

Can the UJA1079ATW/3V3/WDJ supply more than 250 mA to the microcontroller?

Yes - the UJA1079ATW/3V3/WDJ's 3.3 V regulator delivers up to 250 mA directly, and supports external current boosting via an external PNP transistor connected to VEXCTRL and VEXCC. The activation threshold is programmable (50 mA or 85 mA rising edge), enabling scalable power delivery while distributing thermal load across the PCB.

How does the UJA1079ATW/3V3/WDJ handle LIN bus faults such as short-to-battery or short-to-ground?

The UJA1079ATW/3V3/WDJ LIN bus pin (LIN, pin 25) is rated ±58 V short-circuit proof and protected per ISO 7637-3 for transient immunity. It withstands direct short-to-battery events without latch-up or damage and recovers automatically after fault removal. No external protection components are required for standard automotive harness environments.

What is the purpose of the LIMP output on the UJA1079ATW/3V3/WDJ, and when is it activated?

The LIMP output (pin 17) is a fail-safe open-drain signal driven LOW during Overtemperature mode or upon software activation via the LHC bit. It directly controls external 'limp home' hardware (e.g., backup fans or lights) to maintain basic functionality during critical failures. Activation is hardware- and software-triggered, ensuring redundancy in safety-critical paths.

Is the UJA1079ATW/3V3/WDJ pin-compatible with other members of the UJA107x family?

No - the UJA1079ATW/3V3/WDJ is not pin-compatible with UJA1076 or UJA1078 variants due to differences in feature sets (e.g., LIMP, VEXCTRL/VEXCC, EN functionality) and internal routing. While all share the HTSSOP32 package, pin assignments for control signals (e.g., EN, LIMP, VEXCTRL) differ, requiring unique PCB layouts for each variant.