Monolithic Power Systems Inc. MP174AGJ-Z

Overview

MP174AGJ-Z from Monolithic Power Systems is a 700V primary-side constant-voltage (CV) regulator with integrated MOSFET, supporting buck, buck-boost, boost, and flyback topologies in non-isolated off-line power supplies. It delivers up to 400mA output current in CCM mode, achieves <30mW no-load power consumption, and features frequency foldback and peak-current compression for high light-load efficiency - deployed in home appliance standby power and white-goods auxiliary supplies.

For engineers reviewing the MP174AGJ-Z datasheet, MP174AGJ-Z pinout, MP174AGJ-Z application, or MP174AGJ-Z equivalent, key selection criteria include its TSOT23-5 package footprint, 700V/13.5Ω integrated MOSFET, VCC UVLO thresholds (5.1–5.3V turn-on, 5.4–5.6V turn-off), 2.55V FB reference, and thermal shutdown at 150°C with 30°C hysteresis.

Technical Context

The MP174AGJ-Z implements primary-side regulation using internal error amplifier sampling 6μs after MOSFET turn-off, referenced to a 2.55V precision bandgap. Its green-mode operation dynamically reduces switching frequency and peak current under light load via off-time extension and current limit compression.

Protection logic includes auto-restart OLP triggered by FB voltage dropping below 1.7V for 220ms, SCP activation at 750–900mA peak current with 180ns blanking, open-loop detection at FB <0.5V, and OTP at 150°C with recovery at 120°C. The IC uses leading-edge blanking (350ns) and ramp compensation scaled to load conditions.

Key Specifications

Pinout & Package

MP174AGJ-Z is housed in a thermally enhanced TSOT23-5 package with exposed drain pad for improved heat dissipation. Pin 1 is VCC, Pin 2 is FB, Pins 3 and 4 are SOURCE (internally tied), and Pin 5 is DRAIN. Pins 5, 6, and 8 of SOIC-8 are N/C - not present in TSOT23-5 variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP174AGJ-Z, MP173AGJ-Z sacrifices light-load efficiency and surge margin for lower unit cost, while LNK304DG-TL trades primary-side simplicity for tighter regulation and higher power - making MP174AGJ-Z optimal for cost-sensitive, ultra-low-standby, and compact non-isolated designs.

Availability

MP174AGJ-Z is available at Aetrix Electronics and suitable for home appliance standby supplies, white-goods auxiliary rails, and consumer electronics adapters requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP174AGJ-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 focus on energy-efficient DC/DC conversion, motor drivers, and power management solutions.

The MP174A product line targets ultra-low-power, non-isolated off-line regulation - designed specifically to replace linear and transformer-based standby supplies in cost- and space-constrained consumer and industrial applications.

FAQ

What is the maximum recommended output power for MP174AGJ-Z in TSOT23-5 package?

The TSOT23-5 package has a θ_JA of 100°C/W and 1W maximum continuous power dissipation at 25°C ambient. With 700V/13.5Ω MOSFET and typical 400mA CCM output, practical output power is limited to ≤5W - but thermal derating above 60°C ambient requires reducing load current or adding copper pour to the DRAIN pad.

Can MP174AGJ-Z operate in flyback topology with primary-side regulation?

Yes - the MP174AGJ-Z supports flyback topology with primary-side CV regulation using a reflected-voltage sampling network. It does not require an optocoupler or secondary-side feedback; instead, it infers output voltage from the demagnetization time and auxiliary winding voltage, enabling isolated yet simplified designs.

How does the MP174AGJ-Z achieve <30mW no-load consumption?

It combines green-mode operation (frequency foldback + peak-current compression), low VCC operating current (200μA no-switching), internally biased VCC, and <16μA latch-off phase discharge current. These reduce dynamic and static losses simultaneously - verified at 265VAC input with 12V/0mA output and standard external components.

What is the purpose of the 350ns leading-edge blanking (LEB) on the current sense path?

The 350ns LEB disables the current comparator immediately after MOSFET turn-on to ignore parasitic turn-on spikes caused by freewheeling diode reverse recovery and layout inductance. This prevents false overcurrent triggering and ensures reliable switching cycle initiation under all load and input conditions.

Does MP174AGJ-Z require an external VCC capacitor, and what value is recommended?

Yes - a 1–4.7μF ceramic or low-ESR electrolytic capacitor is required between VCC and SOURCE. It sustains control circuit operation during MOSFET off-time and provides charge reservoir for startup. Larger values improve hold-up but increase start-up time; 2.2μF is typical for 12V output designs.

How is open-loop detection implemented, and what triggers it?

Open-loop detection monitors FB voltage continuously; if FB falls below 0.4–0.6V (typ. 0.5V) for >1 switching cycle, the IC halts switching and initiates auto-restart. It is blanked for the first 512 cycles to tolerate large output capacitors during startup - preventing false trips during soft-start or transient events.

Is MP174AGJ-Z compliant with RoHS and REACH regulations?

Yes - MP174AGJ-Z is lead-free, halogen-free, and fully compliant with EU RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. Full compliance documentation, including material declarations and test reports, is available through MPS Quality Assurance portal.