STMicroelectronics STEVAL-ISA109V2

Overview

STEVAL-ISA109V2 from STMicroelectronics is an evaluation board for the STBB2 dual-mode buck-boost DC-DC converter, supporting 2.3 V–5.5 V input and delivering regulated 3.3 V at up to 800 mA with 3 MHz switching frequency. It demonstrates adjustable-output operation (VSEL tied to VIN) and supports fixed-output configuration via resistor rework.

For engineers reviewing the STEVAL-ISA109V2 datasheet, STEVAL-ISA109V2 schematic, STEVAL-ISA109V2 application, or STEVAL-ISA109V2 equivalent, this board enables rapid validation of high-frequency, compact buck-boost power stages in space-constrained portable and battery-powered systems where input voltage may fall below or rise above the required output.

Technical Context

The board implements the STBB2 IC in adjustable mode with feedback resistors pre-configured for 3.3 V output; VSEL pin hardwired to VIN selects the adjustable variant. Input voltage range (2.3 V–5.5 V) and 3 MHz constant-frequency operation enable stable regulation across wide battery discharge curves while minimizing external passive size.

It supports reconfiguration to fixed-output mode by replacing R1 with a 0 Ω jumper and removing R2-demonstrating both variants of the same STBB2 die. No external compensation components are required, as the STBB2 integrates type-II compensation.

Key Specifications

Availability

STEVAL-ISA109V2 is available at Aetrix Electronics and suitable for portable medical monitors, wearable health sensors, and ultra-compact IoT edge nodes requiring stable component supply and fast power architecture validation.

Supply support for STEVAL-ISA109V2 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 analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The STEVAL-ISA109V2 belongs to ST's STEVAL evaluation board series, developed specifically to accelerate design-in of ST's high-efficiency, high-frequency DC-DC converters in battery-fed applications with tight PCB area constraints.

FAQ

What is the primary purpose of the STEVAL-ISA109V2?

This board is a dedicated evaluation platform for the STBB2 buck-boost converter IC. It allows engineers to verify performance-including efficiency, transient response, and thermal behavior-under real-world input conditions (2.3–5.5 V), with factory-set 3.3 V output and full access to test points for probing key nodes like SW, FB, and VSEL.

Can the output voltage be adjusted to values other than 3.3 V?

Yes. The board uses an external resistor divider on the FB pin to set output voltage. By changing R1 and R2 values per the STBB2 datasheet's feedback equation, users can configure outputs from 1.2 V to 5.5 V. The default 3.3 V setting uses specific resistor ratios confirmed in the reference schematic (DocID024566 Rev 1).

How do I switch from adjustable to fixed-output mode?

To use the fixed-output version of STBB2, replace R1 with a 0 Ω resistor and remove R2 entirely. This connects the internal reference directly to FB, enabling one of the factory-trimmed fixed outputs (e.g., 3.0 V or 3.3 V depending on STBB2 variant). The board layout supports this rework without signal integrity compromise.

Is the STEVAL-ISA109V2 suitable for production use?

No. It is strictly an evaluation tool-not qualified for volume deployment. It lacks conformal coating, production-grade thermal vias, or long-term reliability validation. For production, designers must implement the STBB2 in their own layout following ST's recommended footprint, grounding, and layout guidelines from AN4407 and the STBB2 datasheet.