1 General description

The TJA1446 is a high-speed CAN transceiver that provides an interface between a controller area network

(CAN) or flexible data rate CAN (CAN FD) protocol controller and the physical two-wire CAN bus. TJA1446

transceivers implement the CAN physical layer as defined in ISO 11898-2:2024 and SAE J2284-1 to SAE

J2284-5, making them fully interoperable with high-speed classical CAN and CAN FD transceivers. The

TJA1446 was developed in compliance with ISO 26262, achieving ASIL B.

The TJA1446 features very low power consumption in Standby and Sleep modes. It supports CAN partial

networking by means of selective wake-up functionality as specified in ISO 11898-2:2024, making the TJA1446

the ideal choice for CAN system implementations where only nodes that are needed are to be activated.

Nodes that are not needed for the function being performed can be powered down to minimize system power

consumption, even when CAN bus traffic is running.

The TJA1446 includes a comprehensive set of features including two configurable general-purpose I/O pins

(GPIO), an SPI for configuration, mode control and diagnostics, a question & answer (Q&A) watchdog with

dedicated reset and failsafe/limp home pins and accurate VIO undervoltage and overvoltage monitoring.

The TJA1446 can be configured to ignore CAN FD frames while waiting for a valid wake-up frame. This

additional feature of partial networking, called CAN FD passive, is the perfect fit for networks that support a mix

of classical CAN and CAN FD communication.

The TJA1446 comes in three variants:

• TJA1446A supporting 1.8 V VIO supply and monitoring

• TJA1446B supporting 3.3 V VIO supply and monitoring

• TJA1446C supporting 5 V VIO supply and monitoring

2 Features and benefits

2.1 General

• ISO 11898-2:2024 parameter sets A-B, SAE J2284-1 to SAE J2284-5 and SAE J1939-14 compliant

• ISO 26262, ASIL B compliant

• Partial networking capability through selective wake-up functionality

• Q&A watchdog with window and timeout modes

• Configurable general-purpose I/O (GPIO) pins

• Second RXD and/or TXD pins (RXD2/TXD2), configurable via GPIO

• Direct transmitter on/off control input (TXEN_N) via GPIO

• Autonomous bus biasing

• Low electromagnetic emission (EME) and high electromagnetic immunity (EMI)

• Qualified according to AEC-Q100 Grade 1

• VIO input for interfacing with 1.8 V, 3.3 V to 5 V microcontrollers

• ListenOnly mode for node diagnosis and failure containment

• DHVQFN18 package (3.0 mm × 4.5 mm) with automatic optical inspection (AOI) capabilities

• Option to disable Sleep mode

• Software Development mode

• Dark green product (halogen free and restriction of hazardous substances (RoHS) compliant)

• Selectable interrupts on RXD; option to signal only wake-up and power-on related interrupts or all interrupts

• 4-byte general-purpose memory

• SPI system reset

• End-of-line microcontroller flashing support through CAN pins

• Selectable WAKE pin filter time

2.2 Predictable and fail-safe behavior

• Undervoltage detection on all supply pins with defined behavior below the undervoltage thresholds

• Functionality guaranteed from the undervoltage detection thresholds up to the maximum limiting voltage

values

• Transceiver disengages from the bus (high-ohmic) when the battery voltage drops below the Off mode

threshold

• Internal biasing of TXD to enable defined fail-safe behavior

• Dedicated failsafe pin, configurable for limp-home or failsafe output functionality

• Dedicated reset pin for triggering and detecting reset events

2.3 Low-power management

• Very low-current Standby and Sleep modes, with local and remote wake-up capability

• Local wake-up via the WAKE pin

• Remote wake-up via a wake-up pattern (WUP) or wake-up frame (WUF)

• Configurable CAN wake-up pattern (dom-rec-dom or dom-rec-dom-rec) according to ISO 11898-2:2024.

• Selective wake-up according to ISO 11898-2:2024

• Entire node containing the TJA1446 can be powered down via INH while still supporting local and remote

wake-up

• Only VBAT is needed to support local and remote wake-up

• Support for pretended networking through low-power ListenOnly mode.

2.4 Diagnosis and Protection

• Overtemperature diagnosis and protection

• Overvoltage detection with defined behavior on VIO supply pin

• Transmit data (TXD) dominant time-out diagnosis and protection

• Bus dominant failure diagnosis

• Cold start diagnosis (first battery connection)

• High ESD handling capability on the bus pins

• Bus pins and VBAT protected against automotive transients