STMicroelectronics STEVAL-ISA020V1

Overview

STEVAL-ISA020V1 from STMicroelectronics is a 3.5 W AC-DC battery charger demonstration board based on the VIPer12AS-E primary switcher and TSM101 voltage/current controller, delivering 0–7 V at 0.5 A output with low-battery detection signal, designed for NiCd/NiMH single-cell charging applications.

For engineers reviewing the STEVAL-ISA020V1 datasheet, STEVAL-ISA020V1 pinout, STEVAL-ISA020V1 application, or STEVAL-ISA020V1 equivalent, this board supports rapid evaluation of offline flyback topology, integrated current/voltage regulation, and cost-optimized single-output battery charging design under universal AC input (88–264 Vac, 50–60 Hz).

Technical Context

The board implements a discontinuous conduction mode (DCM) flyback converter using VIPer12AS-E - an integrated 800 V avalanche-rugged MOSFET + PWM controller - with primary-side regulation enabled by optocoupler feedback (SFH617A-3) and secondary-side monitoring via TSM101's dual op-amps and reference.

TSM101 provides real-time battery voltage sensing (via resistive divider R14/R16), charge current limiting (R18 sense resistor), and low-battery flag generation (open-collector output at U2 pin 5), all operating without external microcontroller intervention.

Key Specifications

Availability

STEVAL-ISA020V1 is available at Aetrix Electronics and suitable for battery-powered medical devices, portable test equipment, and industrial handheld chargers requiring stable component supply and proven reference design validation.

Supply support for STEVAL-ISA020V1 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, analog ICs, and automotive-grade silicon.

This board belongs to ST's STEVAL (ST Evaluation) series - purpose-built reference designs that accelerate prototyping of power conversion, battery management, and sensor interface subsystems for industrial and consumer applications.

FAQ

What is the maximum battery voltage supported by STEVAL-ISA020V1?

The board delivers up to 7 V output, configurable via P5, and is intended for single-cell NiCd/NiMH batteries (nominal 1.2 V, fully charged ~1.4 V). It is not rated for Li-ion or multi-cell stacks due to lack of overvoltage protection beyond 7 V and absence of CC/CV charge algorithm implementation.

Does STEVAL-ISA020V1 include full charge termination logic?

No. The board implements constant-current charging and low-battery detection but lacks delta-V, dT/dt, or timer-based full-charge cutoff. Termination must be handled externally or via host system monitoring of the low-battery flag and output voltage.

Can the output voltage be fixed instead of adjustable?

Yes. Replace potentiometer P5 with two fixed resistors forming the same voltage divider ratio (e.g., 10 kΩ top + 1.5 kΩ bottom for ~6.0 V output), maintaining TSM101 feedback node (pin 2) bias within 2.5 V ±0.1 V for stable regulation.

Is the VIPer12AS-E used in its standard 8-pin DIP package on this board?

Yes. U1 is mounted as VIPer12AS-E in 8-pin DIP package (SO-8 footprint not used); pinout matches ST's official VIPer12AS-E DIP datasheet: pins 1–2 = Drain, pin 3 = VDD, pin 4 = FB, pins 5–8 = Source, with internal high-voltage startup circuit active from rectified AC line.