AST1S31HF

Overview

The AST1S31HF is an internally compensated, fixed-frequency PWM synchronous step-down regulator designed for automotive applications. It operates with an input voltage range of 2.8 V to 4 V and provides a regulated output voltage adjustable from 0.8 V up to the input voltage level. The device delivers a DC output current of 3 A at a switching frequency of 2.3 MHz. Key internal components include a 70 mΩ high-side switch and a 55 mΩ synchronous rectifier. It features peak current mode control with internal compensation, integrated soft-start, enable functionality, power good indication, cycle-by-cycle current limiting, and current foldback short-circuit protection. The component is available in a 3 mm x 3 mm, 8-lead VFDFPN package.

Feature Summary

• AECQ100 qualified for automotive reliability standards
• High efficiency operation enabled by low on-resistance integrated power MOSFETs
• Compact solution design supported by internal compensation and minimum external component count
• Comprehensive protection mechanisms including cycle-by-cycle current limiting and current foldback short-circuit protection

Applications

• Automotive electronic systems requiring efficient DC/DC conversion
• Power supply designs for automotive-grade microcontrollers and sensors
• Systems utilizing all ceramic capacitors for compact footprint requirements

Procurement Notes

Verify that the specific orderable part number matches the AST1S31HF designation exactly. Confirm that the delivered components carry the appropriate AEC-Q100 qualification documentation required for automotive integration. Ensure the package type corresponds to the 3 mm x 3 mm, 8-lead VFDFPN specification. Check for any specific ordering suffixes that may indicate tape and reel quantities or variant differences, as these do not alter the electrical function but affect logistics.

Selection Notes

Select this regulator when designing automotive power architectures that require a wide input voltage range of 2.8 V to 4 V. It is suitable for applications needing a 3 A output capability with high efficiency at low output voltages. The internal compensation simplifies the design process by reducing the number of external components needed. Consider this device for space-constrained layouts due to its small DFN package and high switching frequency which allows for smaller passive components.

Part Context

The AST1S31HF belongs to STMicroelectronics' portfolio of automotive-grade power management solutions. It is specifically engineered to meet the stringent reliability and performance demands of the automotive industry. The device complements other power management ICs by providing a robust, high-efficiency step-down conversion stage. Its design focuses on minimizing board space while maintaining stability and protection features essential for critical vehicle electronics.

Replacement Considerations

No public confirmed substitute part numbers are documented for the AST1S31HF.