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1.5 A / 3.3 V step-down DC-DC converter demonstration board based on the ST1S03
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The STEVAL-ISA042V2 demonstration board is a step-down DC-DC converter optimized for powering the low-voltage digital core in HDD applications and, more generally, replacing the high-current linear solution when the power dissipation may cause excessive heating of the application environment. It provides up to 1.5 A over an input voltage range of 3 V to 16 V.

A high switching frequency (1.5 MHz) allows the use of tiny surface-mounted components, as well as the use of a resistor divider to set the output voltage value. Only an inductor, a Schottky diode, and two capacitors are required. 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 thermal protected and current limited to prevent damage due to accidental short-circuits.

It uses the ST1S03 device.

The ST1S03 is available in a DFN6 (3x3mm) package.

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Data Brief

Key Features

  • Adjustable current-mode PWM step-down DC-DC converter
  • Output voltage, Vout : 3.3 V
  • Output current, Iout: 1.5 A
  • Internal compensation to eliminate additional components
  • Pulse skipping for Ioutlower than 15 mA, to maintain the regulation with light loads
  • RoHS compliant

Design Resources


Technical Documentation

Product Specifications

Description Version Size
DB1132: 1.5 A / 3.3 V step-down DC-DC converter demonstration board based on the ST1S03
1.1 89 KB

Presentations & Training Material


Description Version Size
Evaluation board presentation
1.1 432 KB

Hardware Resources

Board Manufacturing Specification

Description Version Size
PCB layout
1.0 32 KB

Bill of Materials

Description Version Size
Bill of materials
1.0 45 KB

Schematic Pack

Description Version Size
Board schematic
1.0 39 KB

Sample & Buy

Part Number Marketing StatusCore ProductOrder From STUnit Price (US$)*
@ 1
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
STEVAL-ISA042V2ActiveST1S03PURBuy Direct30.62Distributor reported inventory date: 2016-02-05
Distributor NameRegionStockMin. order
Newark Element14Order NowAMERICA30

(*) 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
(**) 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.
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