STMicroelectronics STEVAL-L6981NDR

Overview

STEVAL-L6981NDR from STMicroelectronics is an evaluation board based on the L6981NDR synchronous step-down DC-DC converter, delivering up to 1.5 A at output voltages from 0.85 V to VIN, with fixed 3.3 V/5 V options, 3.5–38 V input range, and low-noise mode (LNM) operation for industrial power systems.

For engineers reviewing the STEVAL-L6981NDR datasheet, STEVAL-L6981NDR pinout, STEVAL-L6981NDR application, or STEVAL-L6981NDR equivalent, this board enables rapid validation of L6981NDR's constant-frequency LNM performance, EN-controlled sequencing, thermal protection behavior, and EMI-filtered 38 V industrial supply implementation.

Technical Context

The STEVAL-L6981NDR implements peak current mode control using the L6981NDR IC in SO-8 package, with internal compensation, fixed 1.3 ms soft-start, and EN/SYNC pin supporting enable control and external clock synchronization exclusively for LNM variants.

It integrates pulse-by-pulse current sensing on high-side and low-side MOSFETs, overvoltage protection at FB node, thermal shutdown, and output voltage sequencing capability - all validated on a pre-layout-optimized PCB with optional EMI filter components (L1, L3, C4, C12, C11) and test points for VIN, VOUT, EN, CLK_IN, and GND.

Key Specifications

Availability

STEVAL-L6981NDR is available at Aetrix Electronics and suitable for industrial power systems, factory automation controllers, and programmable logic controller (PLC) power rails requiring stable component supply and fast prototyping of 38 V-input DC-DC conversion.

Supply support for STEVAL-L6981NDR 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 microcontrollers, power management ICs, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The STEVAL-L6981NDR belongs to ST's STEVAL evaluation board family, engineered specifically to accelerate design-in of high-reliability, wide-input-voltage DC-DC regulators in noise-sensitive and thermally constrained industrial environments.

FAQ

What is the primary purpose of the STEVAL-L6981NDR evaluation board?

The STEVAL-L6981NDR is a fully assembled, tested reference design board that demonstrates the L6981NDR synchronous buck converter in Low Noise Mode (LNM), enabling engineers to validate EMI performance, thermal behavior, sequencing, and regulation accuracy before integrating into final industrial power systems.

Does the board support external clock synchronization?

Yes - the EN/SYNC pin (Pin 4 of U1) accepts an external clock signal (TP2), allowing precise frequency alignment with system clocks or other converters to reduce beat frequencies and improve EMI compliance in multi-rail systems.

Can the output voltage be adjusted beyond the fixed 3.3 V or 5 V options?

Yes - by replacing the feedback resistor divider (R1, R3, R6 shown as n.m. or 0 Ω in schematic), users can configure adjustable output from 0.85 V to VIN using the FB pin, per L6981NDR's internal 0.8 V reference and compensation network.

What protection features are implemented and how are they verified on this board?

The board implements overvoltage protection (via FB monitoring), thermal shutdown (via L6981NDR die sensor), and pulse-by-pulse current limiting (on both internal MOSFETs); all are hardware-asserted and observable via PGND voltage collapse, VOUT droop, or EN pin toggling during fault events.