L3751: 6 to 75 V input voltage synchronous buck controller


Wide input voltage range synchronous DC-DC step-down controller features extreme voltage conversion ratio over switching frequency range for improved efficiency, thermals, and ripple performance

This feature-rich buck converter includes a Power Good output useful for monitoring and output voltage sequencing for digital ICs during the power-up phase. Embedded protections ensure controlled and safe operation for critical environments in telecom, networking and industrial applications.

Available in a 20-lead QFN mm package with wettable flanks, its embedded gate driver minimizes the number of external components, lowering BOM costs.

 Read our latest technical bulletin

 techinal bulletin


This article describes a synchronous step-down controller application for the telecom sector and can also be used as a guideline for applications in other sectors. The solution is based on our L3751 synchronous buck controller coupled with the ZC1818 shielded power inductor from Coilcraft for a 60 to 12 V conversion with an output current of 10 to 15 A and delivering up to 180W.

Key features

10 year longevity
  • Wide 6 to 75 V input voltage range
  • Adjustable output voltage from 0.8 to 60V
  • 100 kHz to 1 MHz switching frequency range
  • 40 nsec minimum on-time for extreme duty ratio
  • Internal voltage monitoring
  • Thermal protection
  • Operating junction temperature range: -40 to 150°C

Application examples

 Telecom, networking and industrial applications Telecom, networking and industrial applications
 Failsafe systems Failsafe systems
 Unregulated 24V and 48V input voltage bus Unregulated 24V and 48V input voltage bus
 Conversion from high voltage battery to 12V and 5V rail Conversion from high voltage battery to 12V and 5V rail

Recommended resources

steval l3751v12

This flexible buck converter evaluation board provides a regulated 5 V output at 230 kHz switching frequency with a configurable output voltage and current limit. Compliant with CISPR 16-4-2 standards, the board includes an input filter to reduce EMI.

stsw edsim

Our easy-to-use interactive eDesign tool simplifies designers’ lives! A fast, powerful electrical simulation tool for SMPS and analog ICs featuring enhanced accuracy, eDSim is 10 to 50 times faster than traditional analog SPICE simulators.

dc dc converter pdf

This guide provides developers with an overview of our most commonly used switching regulators and will help identify the most appropriate solution for each type of application.

 The 6V to 75V synchronous buck controller : L3751 

Looking for a synchronous step-down switching controller with extreme conversion ratios for virtually any application? Start by simulating and analyzing L3751 performance in your industrial bus, telecom & networking, and many other applications. 

webinar new power challenges iot automation electrification

Join this on-demand webinar as we explain the different Vbus topologies and associated product portfolios. We will showcase the benefits of our DC-DC and LDO regulators, eFuses, and LED drivers, along with the evaluation boards and free simulation tools available to help designers go to market faster.

We will help you:

  • Understand the advantages of ST power management products in your designs
  • Learn how to effectively identify and select the best regulators for your applications
  • Learn more about our simulation and design aid tool environment