Monolithic Power Systems Inc. MP173AGS-Z

Overview

MP173AGS-Z from Monolithic Power Systems is a 700V primary-side offline regulator IC with integrated MOSFET, supporting buck/boost/buck-boost/flyback topologies for non-isolated AC/DC conversion. It delivers up to 280mA output current in CCM, achieves <30mW no-load power consumption, and features green-mode operation with frequency foldback and peak current compression. It targets standby power and low-power home appliance SMPS designs.

For engineers reviewing the MP173AGS-Z datasheet, MP173AGS-Z pinout, MP173AGS-Z application, or MP173AGS-Z equivalent, key selection criteria include its 700V drain rating, SOIC-8 package thermal performance (θJA = 96°C/W), CV regulation without optocoupler, and integrated protection suite (TSD, OLP, SCP, open-loop detection).

Technical Context

The MP173AGS-Z implements primary-side constant voltage (CV) control using feedback sampling via an external capacitor (C3), eliminating optocoupler dependency. Its internal 700V MOSFET operates with peak current limiting (420mA typ) and minimum off-time control (12μs typ) to regulate output across load conditions.

Green-mode operation dynamically reduces switching frequency and peak current under light loads, enabling <30mW no-load consumption. Protection logic includes auto-restart OLP (220ms delay), SCP with 180ns blanking, and thermal shutdown at 150°C with 30°C hysteresis.

Key Specifications

Pinout & Package

MP173AGS-Z is housed in an SOIC-8 package with exposed pad thermal enhancement. Pin 1 is marked by notch or bevel; pins 5, 6, and 8 are internally not connected (N/C). The DRAIN pin connects directly to high-voltage input; SOURCE serves as ground reference for FB and VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP173AGS-Z, MP174AGS-Z offers higher voltage margin and better EMI performance at the cost of slightly reduced light-load efficiency, while LNK3206G trades green-mode operation for lower system-level BOM count and simpler design - making MP173AGS-Z optimal for balanced efficiency, cost, and regulatory compliance in 1–4W applications.

Availability

MP173AGS-Z is available at Aetrix Electronics and suitable for smart home appliance power, industrial sensor node supply, and consumer electronics standby power requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP173AGS-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 power management ICs, with over two decades of expertise in DC/DC converters, AC/DC controllers, and motor drivers.

The MP173A product line delivers highly integrated, low-noise primary-side regulators targeting cost-sensitive, space-constrained offline power supplies in white goods, industrial controls, and consumer standby systems.

FAQ

What topologies does MP173AGS-Z support, and which require isolation?

The MP173AGS-Z supports buck, boost, buck-boost, and flyback topologies. Only flyback provides galvanic isolation; the other three are non-isolated. Flyback implementation requires an isolated transformer and indirect feedback via auxiliary winding, whereas buck/boost/buck-boost use direct primary-side sensing and deliver referenced output rails.

How does MP173AGS-Z achieve <30mW no-load consumption?

It combines green-mode operation-reducing both switching frequency and peak current under light load-with low VCC operating current (200µA typ in no-switching state), internally biased VCC, and frequency foldback. These features minimize dynamic and static losses simultaneously, meeting strict global energy standards without auxiliary winding or external bias.

Can MP173AGS-Z replace optocoupler-based feedback in existing designs?

Yes, but redesign is required. MP173AGS-Z eliminates the optocoupler and TL431 by using primary-side CV regulation via a feedback capacitor (C3) and resistor divider. Layout must follow MPS guidelines: minimize FB loop area, place C3 close to FB/SOURCE, and avoid routing near noisy nodes like DRAIN or inductor switches.

What is the purpose of the dual DRAIN pins (5 and 7) in SOIC-8?

Pins 5 and 7 are internally bonded to the same DRAIN node to improve current handling and thermal dissipation. This dual-pin configuration lowers effective bond wire resistance and spreads heat across two leads, enhancing reliability in high-voltage switching applications and allowing higher peak current capability within the SOIC-8 footprint.

Does MP173AGS-Z require an external VCC supply for operation?

No - it self-supplies VCC from the DRAIN pin via an internal high-voltage current source. An external VCC supply is optional and only recommended for applications needing <30mW no-load consumption with VO > 7V, where auxiliary bias reduces total system loss. Standard operation uses only the external VCC capacitor (C2) charged from DRAIN.

How does open-loop detection work, and what triggers it?

Open-loop detection activates when FB voltage falls below 0.5V (typ), indicating loss of feedback signal - e.g., due to broken resistor divider or failed capacitor. The IC stops switching and enters auto-restart mode after discharging VCC to VCCPRO (2.5V typ). Detection is blanked for first 512 cycles to avoid false triggers during startup with large output capacitance.