STMicroelectronics STEVAL-ISA055V1

Overview

STEVAL-ISA055V1 from STMicroelectronics is a demonstration board implementing the ST1S12XX synchronous buck converter, delivering 1.2 V at up to 0.7 A with 1.7 MHz fixed-frequency current-mode PWM control, ±3% output voltage tolerance, and integrated enable/soft-start functions. It targets low-voltage digital core power in HDD systems where thermal constraints preclude linear regulators.

For engineers reviewing the STEVAL-ISA055V1 datasheet, STEVAL-ISA055V1 pinout, STEVAL-ISA055V1 application, or STEVAL-ISA055V1 equivalent, this board provides validated layout, component selection (TSOT23-5L-based ST1S12), efficiency >90%, <600 µA quiescent current, and R_DS(on) of 250 mΩ (high-side) / 400 mΩ (low-side) under real operating conditions.

Technical Context

The board implements a fixed-output (1.2 V), current-mode PWM synchronous buck topology using the ST1S12 IC in TSOT23-5L package, operating at 1.7 MHz to minimize external passive size. Input range is 2.5 V–5.5 V, supporting USB-powered and single-cell Li-ion applications.

Thermal protection and cycle-by-cycle current limiting are embedded in the ST1S12 controller, and internal soft-start prevents inrush current. Output ripple is minimized via ceramic capacitors and current-mode control stability without external compensation.

Key Specifications

Availability

STEVAL-ISA055V1 is available at Aetrix Electronics and suitable for hard disk drive (HDD) servo control, portable storage power management, and low-voltage digital core supply applications requiring stable component supply and validated reference design implementation.

Supply support for STEVAL-ISA055V1 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, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The STEVAL-ISA055V1 belongs to ST's ST1S12 evaluation platform series, developed specifically to accelerate adoption of high-efficiency, small-footprint synchronous buck converters for HDD and portable digital core power applications.

FAQ

What input voltage range does the STEVAL-ISA055V1 support?

The board accepts 2.5 V to 5.5 V DC input, compatible with single-cell Li-ion batteries (3.0–4.2 V), USB 5 V supplies (with margin), and regulated 3.3 V rails. This range ensures operation across portable HDD and embedded storage platforms without external LDO pre-regulation.

Does the STEVAL-ISA055V1 include thermal protection?

Yes - the underlying ST1S12 IC integrates thermal shutdown and cycle-by-cycle current limiting. When die temperature exceeds safe threshold or output is shorted, the device halts switching and auto-recovers after cooldown, protecting both board and load during fault conditions.

Can the output voltage be adjusted on this board?

No - STEVAL-ISA055V1 implements the fixed 1.2 V version of the ST1S12. The schematic uses no feedback resistor divider; VFB is internally tied to generate 1.2 V. For adjustable output, ST recommends STEVAL-ISA054V1 (based on ST1S12 adjustable variant).

What package does the ST1S12 IC on this board use?

The ST1S12 IC is mounted in TSOT23-5L package - a 5-pin, 2.9 mm × 1.6 mm surface-mount outline with exposed thermal pad. Pinout matches standard TSOT23-5: VIN, SW, GND, EN, VOUT (feedback pin unused in fixed version).