STMicroelectronics EVAL5970D

Overview

EVAL5970D from STMicroelectronics is an evaluation board for the L5970D 1A step-down switching regulator IC, designed to demonstrate adjustable 1.2V–35V output operation from a 4.4V–36V input, featuring 250kHz fixed-frequency PWM control, internal P-channel MOSFET (R_DS(on) = 250mΩ), and synchronization capability. It supports rapid prototyping of DC-DC converters in industrial power supplies and embedded systems requiring stable 3.3V/5V rails.

For engineers reviewing the EVAL5970D datasheet, EVAL5970D pinout, EVAL5970D application, or EVAL5970D equivalent, this board enables immediate validation of L5970D's voltage feedforward architecture, zero-load current operation, thermal shutdown behavior, and feedback disconnection protection under real-world load transients and input ripple conditions.

Technical Context

The EVAL5970D implements the L5970D IC in a fully assembled SO-8-based reference design with external 33µH inductor, STPS2L25U Schottky diode, 10µF ceramic input capacitor, and 100µF POSCAP output capacitor. It uses a resistive divider (5.6kΩ/3.3kΩ) to set V_OUT = 3.3V and includes SYNC, INH, and COMP terminals accessible via test points for loop compensation and master-slave configuration.

Board-level features include thermal relief on high-current traces, ground plane isolation for FB node integrity, and layout-optimized placement of C3 (220pF) and C4 (22nF) to stabilize the error amplifier and suppress switching noise - directly reflecting ST's recommended PCB implementation per AN2347 and L5970D datasheet Figure 15–17.

Key Specifications

Availability

EVAL5970D is available at Aetrix Electronics and suitable for industrial DC-DC converter development, automotive infotainment power supply qualification, and networking equipment auxiliary rail design requiring stable component supply and documented reference performance.

Supply support for EVAL5970D 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, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The EVAL5970D belongs to ST's Power Management Evaluation Kit family, engineered to accelerate adoption of its monolithic buck regulators by providing production-ready layouts, validated BOMs, and thermal/mechanical documentation aligned with IEC 61000-4 immunity requirements.

FAQ

What input voltage range is validated on the EVAL5970D board?

The EVAL5970D board is validated for 4.4V to 36V DC input per the L5970D datasheet, with test circuits confirming stable 3.3V output across this range. Input capacitors (10µF ceramic + optional bulk) are rated for 25V minimum; operation above 36V violates absolute maximum ratings and risks permanent damage to the L5970D IC or diode.

Can the output voltage be adjusted beyond the default 3.3V?

Yes - the board supports output adjustment from 1.2V to 35V using the FB pin and external resistor divider. The default R1=5.6kΩ/R2=3.3kΩ sets 3.3V; replacing R2 with 10kΩ yields 5.0V, and scaling both resistors maintains regulation accuracy while preserving feedback network impedance per datasheet Section 5.1.

Does EVAL5970D support synchronization with other switching regulators?

Yes - the SYNC pin (Pin 2) accepts TTL/CMOS-compatible clock signals (0.74V–2.5V logic levels) to synchronize the L5970D's 250kHz oscillator. When used as slave, it achieves phase alignment within ±0.35µs pulse width tolerance; as master, it drives up to 0.45mA sink current into another regulator's SYNC input.

What thermal performance can be expected at full 1A load?

At 1A output and 12V input, junction temperature rise is ≤45°C above ambient (measured per Figure 3 and Figure 5), assuming standard 2-layer FR-4 PCB with 1oz copper and no forced airflow. This meets the L5970D's 150°C max T_J limit and confirms SO-8 thermal design viability for continuous industrial operation.