Power supply designed to supply microcontrollers in safety-relevant applications

11-05-2020 | Texas Instruments | Power

Texas Instruments TPS653853A-Q1/TPS653854A-Q1 Multi-Rail Power Supply is designed to supply microcontrollers in safety-relevant applications, such as those seen in the automotive industry. The device supports functional safety microcontrollers with dual-core lockstep and other multi-core architectures. The devices integrate multiple supply rails to power the MCU, CAN or FlexRay, and external sensors. A buck-boost converter, with internal FETs, converts the input battery voltage between 2.3V and 36V to a 6V pre-regulator output that supplies the other regulators. An integrated charge pump gives an overdrive voltage for the internal regulators and can also be employed to drive an external NMOS FET as reverse battery protection. The device supports wake-up from an IGN pin or wake-up from a CAN transceiver or other signal.

The device has a steering-angle monitoring (SAM) unit that enables the ECU to indirectly capture the position of the steering wheel through the motor-position sensors. A dedicated low-power mode enables this SAM unit to operate even when the ECU is in sleep mode. Integrated SAM-switches permit passing-through of the Motor-Position Sensor signals to the MCU during normal operation or decoupling the MCU ADC inputs from the motor-position sensor signals when the ECU is in sleep mode.

An independent voltage monitoring unit inside the device monitors undervoltage and overvoltage on all internal supply rails and regulator outputs of the battery supply. Regulator current limits and temperature protections are also implemented. The devices feature a question-answer watchdog, MCU error-signal monitor, clock monitoring on the internal oscillator, self-check on clock monitor, CRC on non-volatile memory and SPI communication. It also features a diagnostic output pin enabling MCU to observe device internal analog and digital signals, a reset circuit for the MCU (NRES pin), and a safety output (ENDRV pin) to disable external power-stages on any detected system-failure. The device automatically runs a BIST at startup, and the MCU may re-run the BIST during system run time through software control if required. A dedicated DIAGNOSTIC state enables the MCU to check device functionality.

The devices also have an error reporting ability through the SPI register. The device has separate status bits in the SPI register for each particular error on the system level or device level. When the device identifies a particular error condition, it sets the appropriate status bit and retains this status bit set until the MCU reads-out the SPI register in which this status bit was set. Based on which status bit was set, the MCU can determine whether it must keep the system in a safe state or whether it can continue the operation of the system. The devices are AEC-Q100 qualified for automotive applications.

By Natasha Shek