Monolithic Power Systems Inc. MP172GS-P

Overview

MP172GS-P from Monolithic Power Systems is a 700 V primary-side constant-voltage (CV) regulator with integrated MOSFET, supporting buck, boost, buck-boost, and flyback topologies. It delivers up to 120 mA output current in CCM, achieves <30 mW no-load power consumption, and operates across -40°C to +125°C junction temperature for non-isolated off-line power supplies in home appliances and standby systems.

For engineers reviewing the MP172GS-P datasheet, MP172GS-P pinout, MP172GS-P application, or MP172GS-P equivalent, key selection criteria include its 700 V drain-source rating, 2.55 V internal FB reference, frequency foldback behavior, and SOIC-8 package thermal resistance of 96°C/W - all critical for low-power AC/DC converter design and light-load efficiency validation.

Technical Context

The MP172GS-P implements green-mode operation via simultaneous frequency foldback and peak-current compression to maintain high efficiency at light loads. Its primary-side CV regulation eliminates optocoupler dependency by sampling output voltage through an external RC network tied to the FB pin.

Internal protection logic includes auto-restart OLP with 175 ms delay, SCP threshold at 400 mA (typ), thermal shutdown at 150°C with 30°C hysteresis, and open-loop detection triggered below 0.5 V on FB - all managed without external components.

Key Specifications

Pinout & Package

MP172GS-P is housed in a standard SOIC-8 package with exposed thermal pad (not electrically connected), rated for 1 W continuous power dissipation at TA = +25°C and θJA = 96°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP172A-GS-P, MP172GS-P lacks tightened FB tolerance and modernized protection timing, making it less suitable for high-volume consumer products; versus LNK3206G, it eliminates optocoupler dependency but trades off isolation assurance for reduced component count and cost in non-isolated applications.

Availability

MP172GS-P is available at Aetrix Electronics and suitable for home appliance standby power, industrial panel meter auxiliary supplies, and smart sensor node power conversion requiring stable component supply and long-term lifecycle support.

Supply support for MP172GS-P 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 design centers in the US, China, and Taiwan.

The MP172 product line targets cost-sensitive, low-power offline AC/DC conversion where simplicity, minimal BOM, and green-mode efficiency are prioritized over reinforced isolation or ultra-tight regulation.

FAQ

What is the maximum recommended output power for MP172GS-P in continuous conduction mode?

The MP172GS-P supports up to 3 W output power in CCM, verified under 230 VAC input, 5 V output, and 120 mA load. This limit arises from thermal constraints (SOIC-8 θJA = 96°C/W) and peak current saturation at 210 mA, not voltage rating. Exceeding 3 W risks thermal shutdown or regulation loss.

Can MP172GS-P be used in isolated flyback topology without optocoupler feedback?

No - while MP172GS-P supports flyback topology, its primary-side CV regulation relies on sampling the output voltage via a resistive divider and capacitor network referenced to SOURCE. True isolation requires optocoupler-based secondary-side feedback; MP172GS-P's flyback use assumes direct connection between secondary ground and SOURCE, making it non-isolated.

Why does MP172GS-P specify "NOT RECOMMENDED FOR NEW DESIGNS"?

This designation reflects MPS's official position that MP172GS-P has been superseded by the MP172A series, which features improved FB reference accuracy (±1% vs. ±3%), tighter OLP timing, and enhanced ESD robustness. MP172GS-P remains fully functional but is not qualified for new product introductions per MPS documentation.

How is the minimum off time (10 μs) used in practical design?

The 10 μs minimum off time sets the upper bound for switching frequency in DCM operation and directly impacts maximum output power calculation. In buck topology, it limits energy transfer per cycle; designers must select inductance and input voltage such that off time exceeds this value to avoid regulation failure at light loads.

What is the role of the NC pins (4, 5, 6) in SOIC-8 package?

Pins 4, 5, and 6 are unconnected die pads with no internal bond wires. They must remain floating - no routing, soldering, or grounding - to prevent parasitic capacitance, ESD injection paths, or unintended thermal coupling that could destabilize the high-voltage DRAIN node or FB sensing.

Does MP172GS-P support adjustable switching frequency?

No - MP172GS-P uses internally set frequency foldback, ranging from ~36 kHz at full load down to ~10 kHz at light load. Frequency is not externally programmable; variation is automatic and load-dependent, optimized for green-mode efficiency rather than EMI tuning or synchronization.

How does the internal VCC regulator charge the external capacitor?

The internal HV regulator draws current from the DRAIN pin to charge the external VCC capacitor (typically 1–10 µF). When VCC drops below 5.1 V, the HV regulator activates; above 5.7 V, it disables. This self-supply mechanism eliminates need for auxiliary winding while maintaining stable bias under varying line conditions.