The UJA116x family by NXP comprises a CAN high-speed transceiver, 5-V voltage regulator and protected sensor supply as well as a watchdog. The chip comes in a HVSON14 package measuring 3,5 mm x 5,5 mm.
New cars today have over 50 electronic control units, making it imperative for automotive OEMs to select solutions that are compact, cost-efficient and scalable,” said Rob Bouwer, NXPs international product marketing manager. “Our third generation of CAN SBCs builds on our proven track record in connecting the car, addressing the key requirements of Tier 1 automotive suppliers for compact and energy-efficient in-vehicle networking solutions today, and in the future.”
The launched product family ranges from the UJA1161 self-supplied transceiver to the UJA1168 system-basis chip supporting partial networking and tolerating CAN FD frames. The components are compliant to ISO 11898-2. Some variants also comply with ISO 11898-5 (low-power mode) and ISO 11898-6 (selective wake-up function):
ECUs using the components with selective wake-up capability can remain in sleep-mode until they are awoken by the transceiver. This happens only when the configured wake-up message is detected. This reduces power consumption in particular for those ECUs rarely active, e.g. power windows and power mirrors.
A number of configuration settings are stored in non-volatile memory, allowing the SBC to be adapted for use in a specific application. This makes it possible to configure the power-on behavior of the chip. The mode control is done via the SPI (Serial Peripheral Interface) port. The components include a 5-V/100-mA voltage regulator and provide a ±8-kV ESD (electro-static discharge) protection on the CAN pins. The CAN pins are short-circuit proofed to ±58 V.
Modes of operation
In normal mode, the CAN transceiver is available and the voltage regulator is enabled to supply the micro-controller. The CAN transceiver can be configured to be active and thus to support normal network communication. Depending on the SPI register settings, the watchdog may be running in Window or Timeout mode and the INV/VEXT output may be active.
In standby mode, the first power-saving level, the current consumption is reduced. The transceiver is unable to transmit or receive data. The SPI remains enabled and V1 is still active; the watchdog is active if enabled. If remote CAN wake-up is enabled, the receiver monitors the network activity for a wake-up request. The network pins are biased to GND when the network is inactive for some time and at approximately 2,5 V when there is activity on the network (autonomous biasing). CAN wake-up can occur via wake-up pattern or via a selective wake-up frame.
Sleep mode is the second-level of power saving. The difference to the standby mode is that V1 is off. This mode can be permanently disabled in applications in which, for safety reasons, the supply voltage to the host controller must never be cut off.
The SBCs also provide reset, off, over-temperature, and forced normal modes. The forced normal mode simplifies testing and is useful for initial prototyping and failure detection, as well as first flashing of the micro-controller. In this mode, the watchdog is disabled.
The over-temperature mode prevents the chip being damaged due to high temperatures. The SBC switches to off mode when the battery is first connected. In this mode, only power-on detection is enabled, all other functions are inactive. The chip starts to boot-up when the battery voltage rises above the power-on detection threshold and switches to reset mode after the startup time. In off mode, the CAN pins disengage from the network (zero load; high-ohmic). The reset mode ensures that the RSTN pin is pulled down for a defined time to allow the micro-controller to start up in a controlled manner. The transceiver is unable to transmit or receive data.
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