Monolithic Power Systems Inc. EV023-S-00A

Overview

EV023-S-00A from Monolithic Power Systems is an evaluation board built around the MP023GS primary-side regulated (PSR) flyback controller, designed to demonstrate a universal-input 5V/2.4A (12W) cell phone charger reference design operating from 85–265VAC at 50/60Hz. It implements a single-stage flyback topology with synchronous rectification (MP6906J + AP9990GMT-HF), achieves >83% full-load efficiency, meets EN55022 conducted EMI limits, and integrates OVP, OCP, OTP, and VCC UVLO protections.

For engineers reviewing the EV023-S-00A datasheet, EV023-S-00A pinout, EV023-S-00A application, or EV023-S-00A equivalent, this board serves as a validated hardware platform for rapid prototyping of cost-sensitive, compact AC/DC adapters targeting handheld electronics - with emphasis on no-optocoupler control, <20mW no-load consumption, and programmable cable compensation.

Technical Context

The EV023-S-00A implements a primary-side-controlled flyback converter using the MP023GS SOIC8-7A controller, eliminating secondary-side feedback components. It employs variable off-time peak current control and precise CC/CV regulation via FB voltage sensing with programmable compensation point, enabling ±5% output voltage and ±8% constant current accuracy across line and load variations.

Input rectification and π-filtering (C1/L1/C2) meet EN55022 Class B conducted EMI requirements; the transformer (EPC17 core, 0.71mH primary inductance, 15µH leakage) is optimized for EMI margin and safety isolation (3000VAC PRI–SEC). Synchronous rectification with MP6906J driver and AP9990GMT-HF MOSFET replaces Schottky diodes to improve efficiency under light-to-full load conditions.

Key Specifications

Availability

EV023-S-00A is available at Aetrix Electronics and suitable for cell phone charger development, handheld electronics adapter qualification, and auxiliary power supply validation requiring stable component supply, pre-validated layout, and documented EMI performance.

Supply support for EV023-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 analog and power ICs, with expertise in DC/DC converters, LED drivers, motor drivers, and AC/DC controllers.

The EV023-S-00A belongs to MPS's evaluation board portfolio for primary-side regulation (PSR) controllers, developed to accelerate adoption of optocoupler-free, low-BOM-cost flyback designs for consumer and industrial power adapters.

FAQ

What is the role of the MP023GS controller on this board?

The MP023GS is a primary-side regulation (PSR) flyback controller that eliminates the need for an optocoupler and TL431 by estimating output voltage and current through primary-side sensing. It provides precise constant-voltage and constant-current regulation, programmable cable drop compensation, and cycle-by-cycle current limiting - all implemented within its SOIC8-7A package.

Can the synchronous rectifier be replaced with a diode?

Yes - the board supports both configurations. The MP6906J-driven AP9990GMT-HF MOSFET can be replaced with Schottky diodes (D5/D6, marked NC on schematic), as noted in the circuit description. This trade-off reduces cost and complexity but lowers efficiency by ~2–3% at full load due to higher conduction losses.

Does this board meet international safety standards?

The EV023-S-00A has been tested to 3000VAC isolation between primary and secondary circuits, satisfying reinforced insulation requirements per IEC61000-4-2. However, it is an engineering prototype without agency certification (e.g., UL, CE, CB); users must perform full safety qualification for end-product compliance.

What is the purpose of R16 (5.1kΩ) on the output?

R16 serves as a dummy load resistor to ensure stable regulation and proper PSR loop operation under no-load or very light-load conditions. Without it, the MP023GS may exhibit output voltage overshoot or instability due to insufficient minimum load for accurate primary-side sensing.

How is EMI performance achieved without a Y-capacitor across primary-secondary boundaries?

CY1 (1nF Y-capacitor) is present between primary ground and secondary ground to suppress common-mode noise. Its placement, combined with the π-input filter (C1/L1/C2), transformer inter-winding shielding, and snubber networks (R5/C5, R19/C15), collectively ensures EN55022 Class B compliance - verified across L/N lines with both floating and earthed output GND.

Is the transformer custom-wound, and are winding details provided?

Yes - the FX0429 transformer uses an EPC17 core with five windings (N1–N5), including triple-insulated wire for N3. Full winding sequence, start/end pins, wire gauge (e.g., 0.23mm, 0.55mm TIW), turn counts (e.g., N1=60T, N2=12T parallel), and varnish/solder specs are documented in the BOM and transformer specification section (pages 8–9).