Up to 4 V, 3 A step-down 2.3 MHz switching regulator for automotive applications

The AST1S31HF is an internally compensated 2.3 MHz fixed frequency PWM synchronous step-down regulator. The AST1S31HF operates from 2.8 V to 4 V input, while it regulates an output voltage as low as 0.8 V and up to VIN.

The AST1S31HF device integrates a 70 mΩ high-side switch and a 55 mΩ synchronous rectifier allowing very high efficiency with very low output voltages.

The peak current mode control with internal compensation deliver a very compact solution with a minimum component count.

The AST1S31HF is available in a 3 mm x 3 mm, 8-lead VFDFPN package.

Key Features

  • AECQ100 qualified
  • 3 A DC output current
  • 2.8 V to 4 V input voltage
  • Output voltage adjustable from 0.8 V
  • 2.3 MHz switching frequency
  • Internal soft-start and enable
  • Integrated 70 mΩ and 55 mΩ power MOSFETs
  • All ceramic capacitor
  • Power Good (POR)
  • Cycle-by-cycle current limiting
  • Current foldback short-circuit protection
  • VFDFPN 3 x 3 - 8L package


Technical Documentation

Product Specifications
Description Version Size
DS10625 DS10625: Up to 4 V, 3 A step-down 2.3 MHz switching regulator for automotive applications 2.0 1 MB

Publications and Collaterals

Description Version Size
AST1S3x family Power optimization for postregulated automotive systems 1.0 896 KB
Description Version Size
Brochure Power management guide 09.2017 3 MB

Tools and Software

Evaluation Tools
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Sample & Buy

Part Number Package Packing Type Marketing Status Unit Price (US$) * Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
AST1S31HF VFDFPN 8 3x3x1.0 Tape And Reel Active 1.258 1000 NEC EAR99 MALAYSIA MORE INFO Get Sample Add to cart DISTRIBUTOR AVAILABILITY

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
AST1S31HF ActiveVFDFPN 8 3x3x1.0AutomotiveEcopack1 0 0

(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.