Synchronous rectification with inhibit, 2 A, 1.5 MHz adjustable, step-down switching regulator

The ST1S09 is a step-down DC-DC converter optimized for powering low output voltage applications. It supplies a current in excess of 2 A over an input voltage range from 2.7 V to 6 V.

A high PWM switching frequency (1.5 MHz) allows the use of tiny surface-mount components.

Moreover, since the required synchronous rectifier is integrated, the number of the external components is reduced to minimum: a resistor divider, an inductor and two capacitors. The Power Good function continuously monitors the output voltage. An open drain Power Good flag is released when the output voltage is within regulation. In addition, a low output ripple is guaranteed by the current mode PWM topology and by the use of low ESR SMD ceramic capacitors. The device is thermally protected and the output current limited to prevent damages due to accidental short circuit. The ST1S09 is available in the DFN6 (3 x 3 mm) package.

Key Features

  • Operating junction temp. -30 °C to 125 °C
  • Utilizes tiny capacitors and inductors
  • Available in DFN6 (3 x 3 mm) exposed pad
  • Non switching quiescent current: (typ) 1.5 mA over temperature range
  • Integrated output over-voltage protection
  • 1.5 MHz fixed frequency PWM with current control mode
  • Typical efficiency: > 90%
  • 2 A output current capability
  • Two versions available: power good or inhibit
  • RDSON (typ) 100 mΩ
  • 2 % DC output voltage tolerance


Technical Documentation

Product Specifications
Description Version Size
DS5342 DS5342: 2 A, 1.5 MHz PWM step-down switching regulator with synchronous rectification 4.1 379 KB

Publications and Collaterals

Description Version Size
Brochure Power management guide 09.2017 3 MB

Tools and Software

Evaluation Tools
Solution Evaluation Tools
eDesignSuite Support & Community

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
ST1S09PUR DFN6 3x3 Tape And Reel Active 0.713 1000 NEC EAR99 PHILIPPINES MORE INFO No availability reported, please contact our Sales office

(*) 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**
ST1S09IPUR ActiveDFN6 3x3IndustrialEcopack2 0 0
ST1S09PUR ActiveDFN6 3x3IndustrialEcopack2 0 0

(**) The Material Declaration forms available on 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.