Monolithic Power Systems Inc. MP174GS-P

Overview

MP174GS-P from Monolithic Power Systems is a 700V primary-side constant-voltage (CV) off-line regulator with integrated MOSFET, supporting Buck, Buck-Boost, Boost, and Flyback topologies. It delivers up to 400mA output current in CCM mode, achieves <30mW no-load power consumption, and operates across -40°C to +125°C junction temperature. It targets non-isolated low-power AC/DC conversion in home appliance standby supplies.

For engineers reviewing the MP174GS-P datasheet, MP174GS-P pinout, MP174GS-P application, or MP174GS-P equivalent, key selection criteria include its 700V/13.5Ω integrated MOSFET, primary-side CV regulation without optocoupler, green-mode frequency foldback, thermal shutdown at 150°C, and SOIC-8 package compatibility for board-level thermal management.

Technical Context

The MP174GS-P implements primary-side regulation using internal error amplifier sampling of FB voltage 6μs after MOSFET turn-off, referenced to a 2.55V internal bandgap. Its green-mode operation dynamically reduces both switching frequency and peak current limit under light load via off-time–dependent peak-current compression.

Protection logic includes auto-restart OLP triggered by FB <1.7V for ≥220ms, SCP activation at 750–900mA peak current with 180ns leading-edge blanking, and OTP shutdown at 150°C with 30°C hysteresis. VCC management uses internal high-voltage startup from DRAIN, with UVLO thresholds at 5.3V (turn-on) and 5.6V (turn-off), plus latch-off discharge at 3.4V stop and 2.4V restart.

Key Specifications

Pinout & Package

MP174GS-P is housed in an SOIC-8 package with exposed pad thermal enhancement. Pin 1 is VCC, Pin 2 is FB, Pins 3 and 4 are SOURCE (internally tied), Pin 5 is N/C, Pin 6 is N/C, Pin 7 is DRAIN, and Pin 8 is N/C. The package supports standard reflow profiles and provides θ_JA = 96°C/W on 4-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP174GS-P, MP173GS sacrifices universal input capability and light-load efficiency for lower unit cost, while LNK306DG trades primary-side simplicity for isolation compliance and tighter regulation-making MP174GS-P optimal for non-isolated, ultra-low-standby applications.

Availability

MP174GS-P is available at Aetrix Electronics and suitable for home appliance standby supplies, smart thermostat power systems, and industrial sensor node PSUs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP174GS-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 global manufacturing and quality certifications including ISO 9001 and IATF 16949.

The MP174 product line delivers highly integrated primary-side regulators targeting cost-sensitive, non-isolated AC/DC conversion in white goods, consumer electronics, and industrial controls-emphasizing ultra-low standby power and simplified bill-of-materials.

FAQ

What topologies does MP174GS-P support, and which require external components?

MP174GS-P supports Buck, Buck-Boost, Boost, and Flyback topologies. Buck and Buck-Boost require only an inductor, freewheeling diode, and output capacitor. Flyback adds a transformer and snubber; Boost needs a boost inductor and output capacitor. All configurations use the same FB resistor divider and VCC decoupling capacitor.

How does MP174GS-P achieve <30mW no-load power consumption?

It combines green-mode operation-reducing switching frequency and peak current under light load-with internal VCC biasing, low ICC (200μA no-switching), and optimized gate drive. The 2.4V restart threshold and 16μA latch-off discharge current minimize VCC capacitor leakage losses during standby.

Can MP174GS-P be used in isolated flyback designs, and what feedback mechanism is employed?

Yes, MP174GS-P supports isolated flyback via indirect feedback using a third winding on the transformer. The FB pin senses reflected voltage from this winding, eliminating optocoupler need. Regulation accuracy depends on transformer turns ratio consistency and winding coupling-typical output tolerance is ±5%.

What is the role of the two SOURCE pins (3 and 4) in SOIC-8, and how should they be connected?

Pins 3 and 4 are internally bonded together as the MOSFET source terminal and serve as the common ground reference for VCC and FB. They must be connected to the same low-impedance power ground plane-never split or routed separately-to prevent noise coupling into the feedback path and ensure stable regulation.

How does the OLP protection trigger, and what is the recovery behavior?

OLP triggers when FB voltage drops below 1.7V for 220ms (at 28kHz switching), indicating sustained overload. Upon activation, the IC stops switching, discharges VCC via 16μA current source, and restarts automatically once VCC falls below 2.4V and rises above 5.3V-providing hiccup-mode protection without manual reset.

Is MP174GS-P RoHS-compliant and halogen-free, and what is its moisture sensitivity level?

Yes, MP174GS-P is lead-free, halogen-free, and fully compliant with EU RoHS Directive 2011/65/EU. It carries MSL-3 rating per J-STD-020, requiring floor life of 168 hours at ≤30°C/60% RH and bake condition of 125°C/8h if exposed beyond that limit before reflow.