STMicroelectronics STEVAL-L3751V12

Overview

STEVAL-L3751V12 from STMicroelectronics is a 100 W synchronous buck evaluation board based on the L3751 voltage-mode controller in VQFN package, supporting 6–75 V input and delivering regulated 5 V or 12 V output at up to 15 A, with 230 kHz default switching frequency and power-good monitoring for telecom and industrial DC-DC conversion.

For engineers reviewing the STEVAL-L3751V12 datasheet, STEVAL-L3751V12 pinout, STEVAL-L3751V12 application, or STEVAL-L3751V12 equivalent, key selection considerations include input voltage range (6–75 V), selectable dual-output voltage (5/12 V), forced PWM/pulse-skipping light-load operation, synchronization capability (185–345 kHz), and integrated thermal/current protections.

Technical Context

The board implements voltage-mode control using the L3751 controller, which features diode emulation (DEM) for pulse-skipping at light load and forced PWM (FPWM) across full load range to maintain constant 230 kHz switching frequency and minimize output ripple. It supports output voltage sequencing via PGOOD open-collector signal for digital IC power-up coordination.

Internal gate drivers supply 7.5 V to standard-threshold MOSFETs (STL90N10F7 high-side, STL110N10F7 low-side), while current sensing uses r_DS(on) of the low-side FET. Protection includes hiccup-mode overcurrent, UVLO (input undervoltage lockout), internal voltage monitoring, and thermal shutdown at 150°C junction temperature.

Key Specifications

Availability

STEVAL-L3751V12 is available at Aetrix Electronics and suitable for telecom power supplies, industrial PLC power modules, and 48 V server auxiliary converters requiring stable component supply, rapid prototyping validation, and reference design reuse.

Supply support for STEVAL-L3751V12 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L3751 product line delivers high-voltage synchronous buck controllers targeting wide-input industrial and telecom DC-DC conversion, emphasizing robustness, integrated protection, and ease of layout with VQFN packaging.

FAQ

What is the default output voltage and how is it changed?

The default output voltage is 5 V, set by factory-configured feedback resistors (R11 = 0 Ω, R12 = 13.3 kΩ, R13 = 2.49 kΩ). To switch to 12 V, install a jumper on J5 pins 1–2 per the schematic - this reconfigures the FB divider ratio. No soldering is required for this change.

Does STEVAL-L3751V12 support external clock synchronization?

Yes - the board accepts an external clock signal (185–345 kHz) on the SYNCIN pin (U1 Pin 8) and provides a buffered SYNCOUT signal (U1 Pin 7) for daisy-chaining multiple converters. This enables EMI reduction through frequency alignment across multi-rail systems.

How is overcurrent protection implemented and reset?

Overcurrent protection uses r_DS(on)-based current sensing on the low-side MOSFET (STL110N10F7) and triggers hiccup mode: the controller shuts down for ~10 ms, then attempts restart. Recovery is automatic after fault removal; no manual reset or external latch is needed.

Can the board operate below 6 V input?

No - the L3751 controller has a hard 6 V minimum VIN specification due to internal bias generation and gate driver requirements. Attempting operation below 6 V will activate UVLO and disable switching; no brown-out recovery or low-VIN fallback mode is supported.