Multi-rail power supply for microcontrollers in safety-relevant applications

The TPS653853-Q1 device is a multirail power supply designed to supply

microcontrollers in safety relevant applications, such as those found in the

automotive industry. The device supports microcontrollers with dual-core lockstep (LS) or loosely

coupled architectures (LC).

The TPS653853-Q1 device

integrates 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 2.3 V and 36 V to a 6-V preregulator output that supplies the other

regulators. An integrated charge pump provides an overdrive voltage for the internal

regulators, and can also be used to drive an external NMOS FET as reverse battery

protection. The device supports wake-up from an ignition signal (IGN pin) or wake-up

from a CAN transceiver or other signal (CANWU pin).

The device has a steering-angle monitoring (SAM) unit that allows the ECU to

indirectly capture the position of the steering wheel through the motor-position

sensors. A dedicated low-power mode allows this SAM unit to operate even when the

ECU is in sleep mode. Integrated SAM-switches allow 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 TPS653853-Q1 device

features a question-answer watchdog, MCU error-signal monitor, clock monitoring on

internal oscillator, self-check on clock monitor, cyclic redundancy check (CRC) on

non-volatile memory and SPI communication, a diagnostic output pin allowing MCU to

observe device internal analog and digital signals, a reset circuit for the MCU

(NRES pin) and a safing output (ENDRV pin) to disable external power-stages on any

detected system-failure. The device automatically runs a built-in self-test (BIST)

at start up and the MCU may re-run the BIST during system run time through software

control if needed. A dedicated DIAGNOSTIC state allows the MCU to check TPS653853-Q1 functionality.

The

TPS653853-Q1 device also has an error reporting capability through the

SPI register. The device has separate status bits in the SPI register for each

specific error on the system level or device level. When the device detects a

particular error condition, it sets the appropriate status bit and keeps 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 decide whether it must keep the

system in a safe state or whether it can resume with the operation of the

system.

The TPS653853-Q1 device is

available in a 48-pin HTSSOP PowerPAD™ IC package.