STMicroelectronics EVAL4971

Overview

EVAL4971 from STMicroelectronics is an evaluation board for the L4971 1.5A step-down switching regulator IC, designed to demonstrate adjustable 3.3V–50V output operation from 8V–55V input. It implements voltage feedforward control, soft-start, pulse-by-pulse current limiting, and thermal shutdown in a DIP8/SO16W-compatible layout using STPS3L60U Schottky diode, 126µH Kool Mu inductor, and precision feedback divider network.

For engineers reviewing the EVAL4971 datasheet, EVAL4971 pinout, EVAL4971 application, or EVAL4971 equivalent, this board enables rapid validation of L4971-based power supply designs targeting industrial DC-DC conversion, battery-powered systems with wide VIN range, and programmable output voltage regulation under load transients and line variations.

Technical Context

The EVAL4971 implements the full functional reference design for the L4971 controller, including external bootstrap capacitor (CBOOT), oscillator timing network (R1=20kΩ, C2=2.7nF), compensation network (C4=22nF, R2=9.1kΩ), and feedback divider (R1/R2) set for 3.3V output. It supports switching frequencies up to 100kHz (standard) and 200kHz (derated), with measured efficiency of 84% at 3.3V/1.5A and 93% at 12V/1.5A from 35V input.

Board-level features include thermal monitoring via PCB copper pour, low-ESR electrolytic input/output capacitors (220µF/63V, 330µF/35V), and layout-optimized high-current paths for the internal 0.25Ω DMOS switch. The board validates protection functions: hiccup-mode short-circuit response, feedback disconnection detection, and inhibit-driven zero-quiescent-current sleep mode.

Key Specifications

Availability

EVAL4971 is available at Aetrix Electronics and suitable for industrial power supply development, battery management system prototyping, and wide-input DC-DC converter qualification requiring stable component supply and documented reference performance.

Supply support for EVAL4971 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, Switzerland, specializing in power management, analog, microcontrollers, and automotive-grade ICs with vertical manufacturing and broad industrial certification coverage.

The EVAL4971 belongs to ST's power evaluation board portfolio, engineered to accelerate adoption of its monolithic step-down regulators-specifically enabling fast validation of high-efficiency, wide-VIN DC-DC designs for harsh-environment applications.

FAQ

What input voltage range does EVAL4971 support?

EVAL4971 supports 8V to 55V DC input, matching the full operational range of the L4971 controller. It has been tested with 8V, 12V, 24V, 35V, and 48V sources, maintaining regulation and protection functionality across all points. Input filtering uses a 220µF/63V low-ESR electrolytic capacitor to ensure stability under transient loads.

Can EVAL4971 be used to evaluate output voltages above 12V?

Yes - EVAL4971 supports output voltages from 3.3V to 50V via external feedback resistor adjustment. The board includes footprint options and layout clearance for resistors up to 30kΩ, enabling configurations such as 15V (R3=16kΩ, R4=4.7kΩ), 24V (R3=30kΩ, R4=4.7kΩ), and 48V (R3=68kΩ, R4=4.7kΩ), all verified per L4971's ±1% reference accuracy.

Does EVAL4971 implement the L4971's soft-start and inhibit functions?

Yes - EVAL4971 fully implements both functions: soft-start time is set by a capacitor on SS_INH (pin 2), and inhibit is accessible via a header pin tied to ground or open-drain logic. Measured quiescent current drops to 150–300µA in inhibit mode, and soft-start delay is configurable from ~10ms to >100ms using 100nF–1µF capacitors, as confirmed in Figure 26 of the L4971 datasheet.

Is thermal performance data available for EVAL4971 under full load?

Yes - thermal imaging and junction temperature measurements show the L4971 remains below 105°C at 1.5A/35V_IN/5.1V_OUT with 200LFM airflow. The DIP8 version dissipates ~800mW (R_th(j-amb) = 90°C/W), and the SO16W version stays within 110°C with board copper pour. Efficiency curves (Figures 16–19) and power dissipation plots (Figures 21–22) are provided in the L4971 datasheet using this board.