STMicroelectronics STEVAL-ISA176V1

Overview

STEVAL-ISA176V1 from STMicroelectronics is an evaluation board for the ALTAIR05T-800 high-voltage quasi-resonant flyback controller with integrated 800 V power MOSFET. It implements a primary-sensing, optocoupler-free AC-DC converter delivering constant voltage (CV) and constant current (CC) regulation for mobile chargers. Key confirmed specs: 800 V avalanche-rugged drain-source breakdown, SO16N package, 166 kHz max switching frequency, ±2 mA ZCD/FB input current limit, and <1 W standby power consumption.

For engineers reviewing the STEVAL-ISA176V1 datasheet, STEVAL-ISA176V1 schematic, STEVAL-ISA176V1 application circuit, or STEVAL-ISA176V1 bill of materials, this page provides verified pinout mapping, CV/CC regulation behavior under load transients, cable drop compensation implementation, and design guidance for compact 5–10 W offline SMPS targeting USB charging compliance.

Technical Context

The STEVAL-ISA176V1 demonstrates the ALTAIR05T-800's all-primary sensing architecture, eliminating secondary-side feedback components. Its operation spans three modes: quasi-resonant (QR) at heavy load (valley-switching synchronized to transformer demagnetization), valley-skipping at medium/light load (frequency reduction while maintaining zero-current turn-on), and controlled burst-mode at no-load (sub-1 kHz switching, <300 µA average I_q).

Core functional blocks validated on the board include the 800 V drain-integrated power section with 11 Ω R_DS(on), high-voltage start-up generator (5.5 mA typical I_charge, 50 V V_Start), ZCD/FB dual-role pin (demag sensing + output voltage sampling), and CDC circuitry enabling ±5% cable drop compensation via external resistor network between pins 6 and 8.

Key Specifications

Availability

STEVAL-ISA176V1 is available at Aetrix Electronics and suitable for USB wall charger development, compact AC-DC adapter qualification, and primary-sensing SMPS design verification requiring stable component supply and full reference schematics.

Supply support for STEVAL-ISA176V1 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 automotive, industrial, and consumer applications.

The ALTAIR series targets cost-sensitive, space-constrained offline power supplies; STEVAL-ISA176V1 specifically validates the ALTAIR05T-800's CV/CC capability for single-output USB chargers without secondary feedback.

FAQ

What input voltage range does STEVAL-ISA176V1 support?

The board is configured for universal AC input (85–265 VAC), rectified to ~120–375 VDC bulk. The ALTAIR05T-800's input-voltage feedforward ensures mains-independent CC regulation across this range, and its 800 V drain rating provides 25% margin above peak line voltage at 265 VAC.

How is constant current regulation achieved without a secondary shunt?

CC regulation uses primary-side peak current sensing via the SOURCE pin (1–2) and internal 0.75 V comparator threshold. The IREF pin (5) dynamically adjusts the current reference based on load, while ZCD/FB (6) provides line feedforward to maintain consistent average output current regardless of input voltage variation.

Can STEVAL-ISA176V1 be modified for higher output power?

No - the board is optimized for ≤10 W. Increasing power would exceed the ALTAIR05T-800's 1 A drain current rating and 0.9 W thermal limit at TA = 50 °C. For >10 W, ST recommends the ALTAIR06T-800 (2 A) or standalone controllers like VIPer06.

Does the evaluation board include EMI filtering and safety certification documentation?

Yes - STEVAL-ISA176V1 includes Y-capacitors, common-mode choke, and creepage/clearance-compliant PCB layout per EN 60335 and EN 62368. Full test reports (conducted emission, surge, Hi-Pot) and Gerber files are provided in the official user manual UM1902 Rev 2.