Monolithic Power Systems Inc. MP020A-5GS-Z

Overview

MP020A-5GS-Z from Monolithic Power Systems is an offline primary-side flyback controller IC with integrated 700V MOSFET, delivering precise constant-current (CC) and constant-voltage (CV) regulation for universal-input AC/DC adapters without optocoupler or secondary feedback. It features 10Ω R_DS(ON), 30mW no-load power consumption, variable off-time DCM control, and full protection suite including OVP (6.35V), OTP (150°C), and OCkP. It targets 5V/1A cell phone chargers operating across 85–265VAC input.

For engineers reviewing the MP020A-5GS-Z datasheet, MP020A-5GS-Z pinout, MP020A-5GS-Z application, or MP020A-5GS-Z equivalent, key selection criteria include its SOIC8-7A package, primary-side CC/CV accuracy (±5% CV, ±8% CC), 120Hz minimum switching frequency, integrated high-voltage start-up current source (550µA), and cable compensation capability up to 2V at full load.

Technical Context

The MP020A-5GS-Z implements primary-side regulation via auxiliary winding voltage sampling at FB, with 3.5µs delayed OVP detection and 120mV DCM threshold monitoring to enforce discontinuous conduction mode. Its peak-current control loop uses internal current sense with 300ns leading-edge blanking and a fixed 380mA typical current limit.

Constant-current regulation relies on zero-current detection (ZCD) sampling of secondary diode conduction duty cycle, enabling output current estimation (I_{O_REF} = 0.152A) independent of transformer turns ratio. Cable compensation is implemented through CP pin voltage generation (0–2V) proportional to load current, converted to FB current injection for dynamic V_OUT adjustment.

Key Specifications

Pinout & Package

MP020A-5GS-Z is housed in a SOIC8-7A package (JEDEC MS-012 compliant), featuring exposed pad thermal enhancement and 0.050" lead pitch. The 8-pin layout supports compact flyback designs with minimal external components.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar primary-side CC/CV flyback controller applications.

Compared with MP020A-5GS-Z, MP023DN-5GS-Z trades output power for lower unit cost in ultra-low-power adapters, while INN2214K adds safety features and precision at the expense of layout compatibility and system-level integration effort.

Availability

MP020A-5GS-Z is available at Aetrix Electronics and suitable for cell phone chargers, handheld electronics adapters, and standby power supplies requiring stable component supply, consistent parametric performance, and long-term industrial availability.

Supply support for MP020A-5GS-Z 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 over two decades of expertise in DC/DC conversion, AC/DC control, and motor drivers.

The MP020A product line delivers highly integrated primary-side regulated controllers for low-power offline adapters, designed specifically to eliminate optocouplers while maintaining tight CC/CV regulation and ultra-low no-load consumption.

FAQ

What is the purpose of the CP pin on MP020A-5GS-Z?

The CP pin generates a 0–2V DC voltage proportional to output load current, which is injected into the FB resistor divider to dynamically compensate for voltage drop across USB cables. This ensures the measured auxiliary winding voltage reflects true output voltage under load, enabling accurate CV regulation at the device connector.

How does MP020A-5GS-Z achieve constant-current regulation without secondary sensing?

It uses zero-current detection (ZCD) of the secondary diode conduction time to estimate output current. The product of ZCD voltage and peak primary current (I_PK) approximates I_{O_REF} = 0.152A. This calculated value is compared against a reference to adjust switching frequency and maintain constant current in DCM operation.

Can MP020A-5GS-Z operate with 230VAC input only, not universal 85–265VAC?

Yes - it supports single-range 230VAC operation. Input bulk capacitors should be halved versus universal-input designs (e.g., ~1µF/W instead of 2–3µF/W), and minimum DC bus voltage must still satisfy Equation (8) to sustain full load. No internal configuration change is required.

What is the function of the 3.5µs delay in FB over-voltage protection?

The 3.5µs delay prevents false OVP triggering caused by switching transients at the FB node. Protection activates only if FB remains above 6.35V for ≥3.5µs, ensuring reliable response to genuine overvoltage faults while ignoring high-frequency noise or ringing during normal operation.

Does MP020A-5GS-Z require an external dummy load for no-load regulation?

A 10mW dummy load is recommended to prevent output voltage rise due to minimum switching frequency limitation at no load. While the IC achieves <30mW no-load consumption, omitting the dummy load may cause CV regulation error exceeding ±5%, especially in high-impedance feedback networks.

How is thermal performance managed in the SOIC8-7A package?

The SOIC8-7A exposes the die paddle as a thermal pad connected to GND pins (2,5,6). At least 1 in² of top-side copper connected to these pins acts as a heatsink. Thermal resistance θ_JA is 76°C/W on a 4-layer PCB per JESD51-7, limiting continuous power dissipation to 1.3W at 25°C ambient.

What protection features activate during open-circuit conditions?

Open-circuit protection (OCkP) triggers when the FB pin fails to detect a 120mV falling edge over successive cycles - indicating no secondary conduction. The IC shuts down driving signals and enters hiccup mode, resuming operation only after the fault is removed and VCC recycles through UVLO.