STMicroelectronics STEVAL-ISA198V1

Overview

STEVAL-ISA198V1 from STMicroelectronics is an evaluation board for the L7987L 61 V, 2 A asynchronous step-down (buck) switching regulator in HTSSOP16 package, delivering 5 V at up to 2 A output with 500 kHz switching frequency, 5 ms soft-start, and ceramic-capacitor compatibility.

For engineers reviewing the STEVAL-ISA198V1 datasheet, STEVAL-ISA198V1 pinout, STEVAL-ISA198V1 application, or STEVAL-ISA198V1 equivalent, key selection factors include input voltage range (4.5–60 V), adjustable soft-start timing, 180° out-of-phase synchronization capability, and integrated overcurrent/thermal protection for industrial power supply validation.

Technical Context

The board implements a fixed 5 V output buck converter using the L7987L IC, which integrates a high-side N-channel MOSFET and supports external frequency adjustment from 250 kHz to 1.5 MHz. It enables out-of-phase synchronization of two regulators to reduce input RMS current ripple.

Soft-start is programmable via external capacitor on SS pin (5.3 ms typical), while current limit threshold (3 A) and feedback loop compensation are configured externally. The VBIAS pin supports switch-over between internal and external biasing to optimize light-load efficiency via pulse-skipping mode.

Key Specifications

Availability

STEVAL-ISA198V1 is available at Aetrix Electronics and suitable for industrial power supply validation, automotive body electronics testing, and embedded system DC-DC reference design requiring stable component supply and documented regulator performance.

Supply support for STEVAL-ISA198V1 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 ICs, sensors, and analog devices for industrial, automotive, and consumer applications.

The STEVAL-ISA198V1 belongs to ST's ST EVAL series of application-specific evaluation boards, developed to accelerate prototyping and validation of their high-voltage buck regulators in real-world power architectures.

FAQ

What is the primary function of the STEVAL-ISA198V1 evaluation board?

The STEVAL-ISA198V1 is a fully assembled and tested demonstration platform for the L7987L buck regulator, configured to deliver 5 V at up to 2 A from a 4.5–60 V input. It validates thermal performance, loop stability, and protection behavior under load transients and fault conditions.

Can the output voltage be adjusted, and how?

Yes - the default 5 V output is set by the R4/R9 resistor divider on the FB pin. To adjust, replace R4 (0 Ω) and R9 (27 kΩ) with values satisfying VOUT = 0.8 V × (1 + R9/R4); minimum supported output is 0.8 V per the L7987L datasheet.

Does STEVAL-ISA198V1 support synchronization with another identical board?

Yes - the SYNCH pin (U1 Pin 7) accepts an external clock signal, and two boards can be configured in 180° out-of-phase synchronization using the FSW pin (U1 Pin 10) as master clock output, reducing total input capacitor RMS current by ~30%.

What type of output capacitors are recommended for this board?

The board is designed and tested with ceramic output capacitors (C5 = 47 µF, C3 = 1 µF, C1 = 4.7 µF), leveraging the L7987L's stability with low-ESR ceramics. Aluminum or tantalum caps are not required and may degrade transient response due to higher ESR.