3 A step-down switching regulator

The L5987 is a step-down switching regulator with a 3.5 A (minimum) current limited embedded Power MOSFET, so it is able to deliver an up to 3 A current to the load depending on the application conditions.

The input voltage can range from 2.9 V to 18 V, while the output voltage can be set starting from 0.6 V to VIN. Having a minimum input voltage of 2.9 V, the device is suitable also for a 3.3 V bus.

Requiring a minimum set of external components, the device includes an internal 250 kHz switching frequency oscillator that can be externally adjusted up to 1 MHz.

The VFQFPN8 and the HSOP packages with an exposed pad allow reducing the RthJAdown to 60 °C/W and 40 °C/W respectively.

Key Features

  • 3 A DC output current
  • 2.9 V to 18 V input voltage
  • Output voltage adjustable from 0.6 V
  • 250 kHz switching frequency, programmable up to 1 MHz
  • Internal soft-start and inhibit
  • Low dropout operation: 100% duty cycle
  • Voltage feedforward
  • Zero load current operation
  • Overcurrent and thermal protection
  • VFQFPN 3 x 3 -8L and HSOP8 package

Circuit Diagram

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Technical Documentation

Product Specifications
Description Version Size
DS5917 DS5917: 3 A step-down switching regulator 4.0 1002 KB
Design Notes & Tips
Description Version Size
DN0011 DN0011: ST1S03 alternative topology: Using a buck in a negative buck-boost configuration 1.1 359 KB

Publications and Collaterals

Description Version Size
Brochure Power management guide 09.2017 3 MB

Tools and Software

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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
L5987TR DFN8 3x3 Tape And Reel Active 0.995 1000 NEC EAR99 PHILIPPINES MORE INFO No availability reported, please contact our Sales office
L5987ATR PowerSO-8 Tape And Reel Active 0.995 1000 NEC EAR99 CHINA 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**
L5987TR ActiveDFN8 3x3IndustrialEcopack2
L5987ATR ActivePowerSO-8IndustrialEcopack2
L5987A ActivePowerSO-8IndustrialEcopack2

(**) 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.