Monolithic Power Systems Inc. MP150GS-Z

Overview

MP150GS-Z from Monolithic Power Systems is a primary-side constant voltage (CV) regulator IC with integrated 500V/30Ω MOSFET, supporting Buck, Buck-boost, Boost, and Flyback topologies for offline low-power AC/DC conversion. It delivers up to 2W output power, achieves <150mW no-load consumption, and features green-mode operation with frequency foldback and peak current compression. It is used in home appliance standby supplies and white-goods auxiliary power rails.

For engineers reviewing the MP150GS-Z datasheet, MP150GS-Z pinout, MP150GS-Z application, or MP150GS-Z equivalent, this page provides verified technical context, SOIC8 package details, CV regulation behavior under light load, thermal shutdown at 150°C, and design guidance for flyback/Buck implementations without optocouplers.

Technical Context

The MP150GS-Z implements primary-side regulation via sampling capacitor-based output voltage sensing, eliminating optocoupler dependency. Its internal 500V MOSFET enables direct high-voltage drain connection, while VCC management uses an internal HV current source with 5.3V turn-on and 5.6V turn-off thresholds.

It employs adaptive green-mode control: switching frequency and peak current limit (290mA typ.) both decrease under light load to maintain efficiency, with minimum off-time fixed at 18μs in steady state. Protection includes OLP (170ms delay at 37kHz), SCP (450mA threshold), TSD (150°C), and open-loop detection (60mV FB threshold).

Key Specifications

Pinout & Package

MP150GS-Z is supplied in SOIC8 package with exposed pad connected to Drain pin for thermal dissipation. Pin 1 is VCC; pins 3 and 4 are SOURCE (common ground reference); pin 7 is DRAIN; pin 2 is FB; pins 5, 6, and 8 are NC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar primary-side offline regulator applications.

Compared with LNK304DG and UCC28910DR, MP150GS-Z offers the lowest component count for sub-2W Buck topologies due to its self-powered VCC architecture and absence of auxiliary winding requirement, while delivering competitive light-load efficiency and simpler PCB layout.

Availability

MP150GS-Z is available at Aetrix Electronics and suitable for home appliance auxiliary supplies, white-goods standby power, and consumer electronics adapters requiring stable component supply, RoHS-compliant packaging, and long-lifecycle availability.

Supply support for MP150GS-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 leadership in DC/DC converters, LED drivers, and AC/DC controllers.

The MP150 product line targets cost-sensitive, low-power offline AC/DC conversion where integration, efficiency, and regulatory compliance are critical-specifically enabling optocoupler-free designs in appliances, IoT edge nodes, and energy-efficient consumer adapters.

FAQ

What topologies does MP150GS-Z support, and which require isolation?

MP150GS-Z supports Buck, Buck-boost, Boost, and Flyback topologies. Only Flyback provides galvanic isolation; the others are non-isolated and deliver referenced outputs. Flyback implementation requires an auxiliary winding or sampling capacitor to reconstruct output voltage on the primary side, while Buck/Buck-boost use direct feedback.

How does MP150GS-Z achieve constant voltage regulation without an optocoupler?

It uses a sampling capacitor charged during the MOSFET off-time to hold the output voltage level. The FB pin monitors this capacitor's voltage, comparing it to the internal 2.55V reference. Regulation occurs by adjusting switching frequency and peak current to maintain FB ≈ 2.55V-no secondary-side sensing or optocoupler needed.

What is the maximum continuous output power achievable with MP150GS-Z in SOIC8 package?

In SOIC8, maximum continuous output power is 2W under forced-air cooling at TA = 25°C. At 5V/200mA, thermal derating begins above 60°C ambient due to θJA = 96°C/W; full 2W output requires heatsink or copper pour on Drain-exposed pad to sustain junction temperature ≤125°C.

Does MP150GS-Z require a minimum dummy load, and why?

Yes-a 2–3mA dummy load is recommended. It ensures sufficient inductor current to charge the sampling capacitor during each off-cycle, maintaining accurate FB voltage reconstruction. Without it, light-load regulation degrades, causing output overshoot or instability in no-load or micro-load conditions.

How does the OLP protection timer behave at different switching frequencies?

The OLP delay scales inversely with switching frequency: τ_OLP ≈ 170ms × (37kHz / f_s). At 50kHz, OLP triggers after ~126ms; at 30kHz, after ~209ms. This ensures consistent overload response time regardless of operating point, avoiding nuisance trips during transient load steps.

Can MP150GS-Z be used in a high-side Buck configuration with positive output?

Yes-MP150GS-Z is explicitly validated for high-side Buck. In this configuration, SOURCE connects to system ground, DRAIN connects to input HV, and the inductor feeds output to load. Output polarity is positive, feedback is direct, and no isolation is provided-ideal for low-cost, non-isolated 5V/12V rails in appliances.

What is the role of the 470pF capacitor between FB and SOURCE pins in typical layouts?

This capacitor filters high-frequency noise on the FB node, preventing false triggering of OLP or regulation errors. Placed close to the IC, it stabilizes the error amplifier input during fast transients and reduces susceptibility to EMI from the drain switching node-critical for reliable CV performance in noisy environments.