STMicroelectronics STEVAL-SMACH15V1

Overview

STEVAL-SMACH15V1 from STMicroelectronics is a USB adapter evaluation board based on the STCH03 offline PWM controller for low-standby AC/DC adapters, delivering 5 V at 3 A continuously with primary-side constant-current (CC) sensing, <15 mW standby power at 230 VAC, and EN55022 Class-B EMI compliance.

For engineers reviewing the STEVAL-SMACH15V1 datasheet, STEVAL-SMACH15V1 schematic, STEVAL-SMACH15V1 application, or STEVAL-SMACH15V1 equivalent, this board enables rapid validation of CC-mode USB charging designs targeting mobile phones, tablets, and handheld devices under EuCoC Rev. 5 Tier 2 and DOE EPS requirements.

Technical Context

The board implements a flyback topology using the STCH03 controller, which integrates a 650 V HV start-up cell and low-voltage PWM controller in one package, enabling primary-sensing CC regulation without secondary-side current sense components. It supports burst-mode operation to maintain ultra-low quiescent current and hiccup-mode protection during transformer saturation or secondary diode short-circuit failure.

Output regulation combines constant voltage (CV) and constant current (CC) modes with hardware-based protections including output overvoltage (OVP), over-temperature (OTP), undervoltage (UVP), and short-circuit limiting. Input power in no-load condition remains below 15 mW at 230 VAC, meeting stringent global energy efficiency mandates.

Key Specifications

Availability

STEVAL-SMACH15V1 is available at Aetrix Electronics and suitable for USB charging design validation, energy-efficient AC/DC adapter development, and low-power flyback reference implementation requiring stable component supply and full regulatory documentation support.

Supply support for STEVAL-SMACH15V1 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 evaluation platforms for industrial, automotive, and consumer applications.

This board belongs to ST's SMACH (Smart Adapter Charger) evaluation series, purpose-built to accelerate development of compact, high-efficiency, standards-compliant USB power adapters using ST's proprietary primary-sensing CC control architecture.

FAQ

What is the primary function of the STCH03 controller on this board?

The STCH03 provides primary-side constant-current (CC) and constant-voltage (CV) regulation for flyback converters, eliminating the need for optocouplers or secondary-side current sense resistors. Its integrated 650 V HV start-up cell and burst-mode control enable <15 mW no-load consumption while maintaining tight output regulation across line and load variations.

Does this board support USB BC 1.2 or USB PD protocols?

No - STEVAL-SMACH15V1 delivers fixed 5 V output only and does not implement USB Battery Charging (BC) 1.2 enumeration or USB Power Delivery (PD) communication. It is a basic CC/CV USB adapter reference design compliant with physical layer power delivery standards, not protocol-aware charging.

Can the output current limit be adjusted without hardware modification?

No - the 3 A current limit is set by R7 (0.47 Ω) and internal STCH03 CC threshold; adjustment requires changing this resistor value and recalibrating feedback loop compensation. The board has no onboard potentiometer or digital interface for dynamic current tuning.

Is the schematic and PCB layout available for reuse in commercial products?

Yes - ST provides the full schematic (DB3654), bill of materials, and Gerber files under ST's standard license terms. Commercial reuse is permitted subject to ST's Evaluation License Agreement, which prohibits resale of the board as-is but allows derivative designs incorporating STCH03 and validated layout practices.