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0.7 A / 1.2 V synchronous buck converter with enable function based on the ST1S12XX
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This demonstration board is based on the ST1S12 family of synchronous step-down DC-DC converters optimized for powering low-voltage digital cores in HDD (hard disk drive) applications and is generally used to replace high-current linear solutions when power dissipation may cause high heating of the application environment.

It provides up to 0.7 A over an input voltage range of 2.5 V to 5.5 V. A high switching frequency of 1.7 MHz allows the use of tiny surface-mount components. For the adjustable version, a resistor divider to set the output voltage value, an inductor, and two capacitors are required. Only an inductor and 2 capacitors are needed for the 1.2 V and 1.8 V fixed version. A low output ripple is guaranteed by the current mode PWM topology and by the use of low ESR surface-mount ceramic capacitors.

The ST1S12 device is thermal protected and current limited to prevent damage due to accidental short-circuit. This family of products is available in the TSOT23-5L package.

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Data Brief

Key Features

  • Step-down current mode PWM (1.7 MHz) DCDC converter
  • Fixed output voltage of 1.2 V
  • 0.7 A output current capability
  • 3% DC output voltage tolerance
  • Synchronous rectification
  • Enable function
  • Internal soft-start
  • Typical efficiency: > 90%
  • Not switching quiescent current: max 600 μA over temperature range
  • RDS(on) typ. 250 m and 400 m
  • Uses tiny capacitors and inductors


Design Resources


Technical Documentation

Product Specifications

Description Version Size
DB0691: 0.7 A / 1.2 V synchronous buck converter with enable function based on the ST1S12XX
1.1 72 KB

Hardware Resources

Board Manufacturing Specification

Description Version Size
Gerber files for STEVAL-ISA055V1 board
1.0 186 KB

Bill of Materials

Description Version Size
BOM for STEVAL-ISA055V1 board
1.0 45 KB

Schematic Pack

Description Version Size
Board schematics for STEVAL-ISA055V1 board
1.0 36 KB

Sample & Buy

Part Number Marketing StatusCore ProductOrder From STUnit Price (US$)*
@ 1
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
STEVAL-ISA055V1ActiveST1S12GR-46Distributor reported inventory date: 2016-02-09
Distributor NameRegionStockMin. order
Newark Element14Order NowAMERICA20

(*) 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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