STMicroelectronics’ SPSA068 is a power management integrated circuit (PMIC) that integrates a synchronous current mode BUCK step-down regulator (with built-in high and low side power MOSFETs) and a high-precision voltage reference. It is both flexible and easy to use, equipped with a complete set of features to meet the functional safety requirements of passenger vehicles, and is compatible with various microcontrollers commonly used in automotive applications. The chip includes input/output monitors, an independent bandgap reference, ground loss detection, digital and analog BIST (built-in self-test), and a dedicated FAULT pin.SPSA068 features configurable parameters and complies with AEC-Q100 standards, supporting ISO 26262 functional safety (FuSa) certification, up to ASIL-B.
SPSA068 is designed for microcontrollers (MCUs) operating under a single power supply, providing all the necessary functions for a turnkey MCU power management solution. It integrates a step-down regulator compatible with a 1A battery, an accurate reference voltage source (1%), a watchdog monitor, diagnostic indicators, MCU reset control, and a serial peripheral interface (SPI) for configuration and status checking.
The device parameters can be customized via non-volatile memory (NVM), which must be programmed by the customer’s production line before first use, as the chip has no default configuration upon leaving the factory. Programmable parameters include: output voltage, switching frequency, spread spectrum switching, protection thresholds, and BUCK current limit values. Since no external setting components are required, the output voltage is not affected by external environmental fluctuations, enhancing both accuracy and safety while reducing the number of external components.The step-down regulator output can be configured to 5V, 3.3V, or 1.2V, with other voltages achievable using external resistors. Load current options are 0.5A or 1A, and the switching frequency can be set to 0.4MHz or 2.4MHz. The reference voltage source can be adjusted to 5.0V, 3.3V, or 1.2V, designed for a 20mA load current. Integrated protections include over-voltage/under-voltage, over-current, short-circuit, and thermal shutdown.
To meet the needs of the MCU, SPSA068 features a low-power mode suitable for light load conditions, with a static current of only 50μA. This mode can be activated via SPI commands; if the system does not require this mode, it can also be disabled in the NVM. The SPI bus is used for chip configuration and communication with the microcontroller: in addition to completing parameter programming, it can also report the status of the regulator’s faults or warnings in real-time.
The PMIC is designed for direct connection to batteries, featuring a comprehensive set of functions and a compact design that ensures efficient use of PCB space and shortens design time. The integrated NVM and low-power mode reduce the system-level sensitivity to environmental conditions, decrease the bill of materials, and enhance accuracy and safety.
With built-in digital and analog self-test (BIST) capabilities, input, output, and ground loss monitors, as well as a dedicated FAULT pin, using the PMIC greatly simplifies the considerations for FuSa. Programming, diagnostics, and monitoring can be performed via SPI, and in the event of faults or warnings, it is equipped with an MCU watchdog and regulator status indicators.