Monolithic Power Systems Inc. EV171A-S-00A

Overview

EV171A-S-00A from Monolithic Power Systems is an evaluation board designed to demonstrate the MP171A primary-side constant voltage regulator in a buck topology, delivering 5V/50mA output from universal 85–265VAC input, with integrated 700V MOSFET, <100mW no-load consumption, and compliance with EN55022 conducted EMI and IEC61000-4-5 Class 3 (2kV) surge immunity.

For engineers reviewing the EV171A-S-00A datasheet, EV171A-S-00A pinout, EV171A-S-00A application, or EV171A-S-00A equivalent, this board enables rapid validation of non-isolated offline CV regulation for low-power AC/DC conversion in cost-sensitive consumer and industrial standby applications.

Technical Context

The EV171A-S-00A implements a fixed-frequency, primary-side regulated buck converter using the MP171AGS IC in SOIC-8 package. It eliminates optocouplers and secondary-side feedback by sensing reflected output voltage via C1 and R1/R2 divider, enabling accurate 5V regulation across 85–265VAC input.

EMI performance is enhanced through CLC filtering (C3–L1–C4), RF1 inrush/surge limiting, and optimized layout per single-sided PCB design. Protection features-including SCP, OLP, open-loop detection, TSD, and VCC UVLO-are exercised directly on the board under real operating conditions.

Key Specifications

Availability

EV171A-S-00A is available at Aetrix Electronics and suitable for home appliance standby supplies, industrial control auxiliary rails, and white goods low-power AC/DC conversion requiring stable component supply and fast prototyping capability.

Supply support for EV171A-S-00A 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance power management ICs, with emphasis on integration, efficiency, and system-level simplification.

The MP171A product line targets cost-sensitive, non-isolated offline regulators for universal-input, low-power (<1W) applications-enabling compact, optocoupler-free AC/DC solutions in consumer and industrial equipment.

FAQ

What is the purpose of the EV171A-S-00A evaluation board?

The EV171A-S-00A is a fully assembled, tested buck-converter evaluation board that demonstrates the MP171A primary-side constant voltage regulator. It validates real-world performance-including efficiency, EMI, surge immunity, and protection behavior-under 85–265VAC input and 5V/50mA output conditions.

Can the EV171A-S-00A be used for Flyback or Boost topologies?

No-the EV171A-S-00A is specifically configured as a buck converter per its schematic and bill of materials. While the underlying MP171A IC supports Buck, Buck-Boost, Boost, and Flyback topologies, this board's layout, component selection (e.g., L1/L2 values, D3 type), and feedback network are optimized exclusively for buck operation.

Does the board include safety agency certification?

No. The documentation explicitly states: "the engineering prototype has not been agency approved." Users must employ an isolation transformer during testing, and the board is intended solely for lab evaluation-not for end-product certification or direct integration into certified systems.

What components enable its EN55022 compliance?

Conducted EMI compliance is achieved via the CLC filter formed by C3 (2.2μF/400V), L1 (1mH), and C4 (2.2μF/400V), along with RF1 (39Ω fuse resistor) for inrush limiting and surge suppression. Layout optimization and grounding strategy further reduce common-mode noise.

How is output voltage regulated without an optocoupler?

Regulation uses primary-side sensing: output voltage is reflected to the FB pin via C1 (22nF sample-hold capacitor) and scaled by R1/R2 (41.2kΩ/39.2kΩ) resistor divider. The MP171A internally compares this signal to its 0.8V reference and adjusts switching duty cycle to maintain 5V output accuracy.

What is the role of R3 on the board?

R3 (1.2kΩ) serves as a mandatory dummy load to ensure stable regulation at no-load conditions. Without it, the 5V rail may rise above specification due to leakage and sampling dynamics in primary-side control; it draws ~4.2mA, keeping the output within ±2% tolerance when unloaded.