STMicroelectronics EVAL5987A

Overview

EVAL5987A from STMicroelectronics is an evaluation board for the L5987 3 A step-down switching regulator IC, designed to demonstrate and validate DC-DC conversion in industrial and consumer power systems. It supports input voltages from 2.9 V to 18 V, delivers up to 3 A output current, features adjustable 250 kHz–1 MHz switching frequency, internal soft-start/inhibit, and operates down to 0.6 V output with 100% duty cycle capability - validated in HSOP8 and VFQFPN3x3 packages.

For engineers reviewing the EVAL5987A datasheet, EVAL5987A pinout, EVAL5987A application, or EVAL5987A equivalent, this board enables rapid prototyping of buck converter designs targeting FPGA/PLD core supplies, LCD TV power rails, and automotive audio subsystems - with direct access to FB, COMP, SYNCH, INH, and FSW signals for loop tuning, synchronization, and enable control.

Technical Context

The EVAL5987A implements a voltage-mode, constant-frequency buck controller based on the L5987 IC, featuring integrated P-channel high-side MOSFET (R_DS(on) = 140–220 mΩ), feedforward-compensated PWM, and programmable oscillator synchronized via the SYNCH pin. Its functional blocks include error amplifier (100 dB gain, 4.5 MHz GBWP), soft-start staircase (64 steps × 9.5 mV), and hiccup-mode overcurrent protection triggered at 3.5–4.4 A.

Thermal management leverages the HSOP8 package's 40 °C/W R_thJA and VFQFPN's 60 °C/W rating, while protection includes UVLO (2.9 V turn-on, 0.175–0.3 V hysteresis), thermal shutdown (150 °C trip, 30 °C hysteresis), and FB disconnection detection (1 µA source current).

Key Specifications

Availability

EVAL5987A is available at Aetrix Electronics and suitable for FPGA power sequencing, LCD TV main rail generation, and automotive infotainment DC-DC conversion requiring stable component supply and fast design validation cycles.

Supply support for EVAL5987A 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, specializing in power management, microcontrollers, and analog ICs - with over 40 years of automotive-qualified and industrial-grade product development.

The EVAL5987A belongs to ST's Power Management Evaluation Kit line, engineered specifically to accelerate adoption of their monolithic buck regulators in space-constrained, thermally demanding applications like set-top boxes and portable displays.

FAQ

What input and output capacitors are pre-installed on EVAL5987A?

The EVAL5987A board uses a 47 µF/25 V low-ESR aluminum polymer capacitor at the input and a 220 µF/6.3 V tantalum capacitor at the output, selected per ST's application note AN2722 to ensure stability across 250 kHz–1 MHz operation and meet RMS current requirements up to 3 A.

Does EVAL5987A support synchronization between multiple boards?

Yes - the EVAL5987A exposes the SYNCH pin of the L5987 IC, enabling master-slave configuration: connecting SYNCH pins of two boards causes the higher-frequency unit to act as master, aligning switching edges with 180° phase shift to reduce input ripple current by up to 30% in multi-rail systems.

Can EVAL5987A be used to evaluate both HSOP8 and VFQFPN package variants of L5987?

No - EVAL5987A is configured exclusively for the L5987A in HSOP8 package, which supports 3 A continuous output with 40 °C/W thermal resistance; the VFQFPN variant requires separate evaluation board EVAL5987D due to different thermal pad layout and PCB footprint.

How is soft-start duration adjusted on EVAL5987A?

Soft-start time is fixed at 7.4–9.1 ms (typ. 8.2 ms) and determined by the L5987A's internal 64-step staircase ramp; it cannot be externally modified on EVAL5987A, but its behavior is fully observable at the COMP pin and correlates directly with switching frequency (T_SS = 2048 / F_SW).