Multi-rail power supply for microcontrollers in safety applications for automotive and industrial market

The Texas Instruments TPS65381A-Q1 device is a multirail power supply designed to supply MCUs in safety-relevant applications, such as those found in automotive and industrial markets. The device supports the company’s Hercules TMS570 MCU and C2000 MCU families, and various other MCUs with dual-core lockstep (LS) or loosely-coupled architectures (LC). The device integrates multiple supply rails to power the MCU, CAN, or FlexRay, and an external sensor. An asynchronous-buck switch-mode power-supply converter with an internal FET converts the input supply (battery) voltage to a 6V preregulator output. This 6V preregulator supplies the other regulators. The device supports wakeup from IGNITION or wakeup from the CAN transceiver. The integrated, fixed 5V linear regulator with internal FET can be used for a CAN or FlexRay transceiver supply for example. A second linear regulator, also with an internal FET, regulates to a selectable 5V or 3.3V output which, for example, can be use for the MCU I/O voltage. The device includes an adjustable linear-regulator controller, requiring an external FET and resistor divider, that regulates to an adjustable voltage of between 0.8V and 3.3V which may be used for the MCU core supply. The integrated sensor supply can be run in tracking mode or adjustable output mode and includes short-to-ground and short-to-battery protection. Therefore, this regulator can power a sensor outside the module or ECU. The integrated charge pump provides overdrive voltage for the internal regulators. The charge pump can also be used in a reverse-battery protection circuit by using the charge-pump output to control an external NMOS transistor. This solution allows for a lower minimum-battery-voltage operation compared to a traditional reverse-battery blocking diode when the device must be operational at the lowest possible supply voltages. The device monitors undervoltage and overvoltage on all regulator outputs, battery voltage, and internal supply rails. A second bandgap reference, independent from the main bandgap reference, is used for the undervoltage and overvoltage monitoring, to avoid any drifts in the main bandgap reference from being undetected. In addition, regulator current-limits and temperature protections are implemented.