Monolithic Power Systems Inc. MP156GJ-P

Overview

MP156GJ-P from Monolithic Power Systems is a primary-side constant-voltage (CV) off-line regulator with integrated 500V/20Ω MOSFET, supporting Buck, Buck-Boost, Boost, and Flyback topologies. It delivers up to 4W output power, achieves <30mW no-load consumption, and features green-mode operation with frequency foldback and peak-current compression for high light-load efficiency - ideal for standby power supplies in home appliances and white goods.

For engineers reviewing the MP156GJ-P datasheet, MP156GJ-P pinout, MP156GJ-P application, or MP156GJ-P equivalent, this device is selected for low-cost, isolated/non-isolated AC/DC conversion where optocoupler-free regulation, thermal shutdown, OLP, SCP, and open-loop protection are required in TSOT23-5 footprint-constrained designs.

Technical Context

The MP156GJ-P implements primary-side CV control using internal sampling capacitor feedback to regulate output voltage without optocoupler or secondary-side sensing. Its error amplifier samples FB voltage 6µs after MOSFET turn-off and applies ramp compensation that scales exponentially with load reduction.

Green-mode operation dynamically reduces both switching frequency and peak current limit (290mA typ → down to ~260mA at light load) as load decreases, minimizing switching and conduction losses. Minimum off-time is 18µs in steady state, with soft-start sequence stepping from 72µs → 36µs → 18µs across 128-cycle intervals.

Key Specifications

Pinout & Package

MP156GJ-P is housed in a TSOT23-5 package with exposed drain pad for thermal enhancement. Pin 1 = VCC, Pin 2 = FB, Pins 3 & 4 = SOURCE (internally tied), Pin 5 = DRAIN. No pins are NC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP157GJ-Z, MP156GJ-P offers lower conduction loss and cost for universal-input consumer applications; versus LNK3206P, it eliminates optocoupler dependency and cuts no-load power by >60%, though with slightly relaxed output accuracy.

Availability

MP156GJ-P is available at Aetrix Electronics and suitable for home appliance control boards, smart sensor hubs, and industrial PLC auxiliary power supplies requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP156GJ-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 MP156 product line targets cost-sensitive, space-constrained off-line AC/DC conversion in consumer and industrial applications, emphasizing integration, energy efficiency, and simplified system design.

FAQ

What topology does MP156GJ-P support without external components?

MP156GJ-P natively supports non-isolated Buck, Buck-Boost, and Boost topologies using direct feedback. For isolated Flyback, it requires only a transformer and basic passive components - no optocoupler, TL431, or secondary-side sensing circuitry. All four topologies are validated in the datasheet with schematic examples and performance curves.

How does MP156GJ-P achieve <30mW no-load power consumption?

It combines three mechanisms: (1) green-mode operation that reduces switching frequency and peak current under light load; (2) internal 16μA latch-off phase current that minimizes VCC discharge loss; and (3) 350ns leading-edge blanking that prevents false triggering and unnecessary switching cycles. These are confirmed in typical performance plots on pages 6–7 of Rev. 1.16 datasheet.

Can MP156GJ-P replace MP156GS in the same PCB layout?

No - MP156GJ-P uses TSOT23-5 (5-pin, 0.95mm pitch), while MP156GS uses SOIC8 (8-pin, 1.27mm pitch). Pin mapping differs: TSOT23-5 has merged SOURCE pins (3&4) and no NC pins; SOIC8 has separate SOURCE (3&4), DRAIN (7), and NC (5,6,8). Layout redesign and footprint change are mandatory for substitution.

What is the minimum recommended output capacitor for stable regulation at 12V/150mA?

A 100μF low-ESR electrolytic or ceramic capacitor is specified in the typical application circuit (page 16). Using <47μF risks excessive output ripple (>100mV) and instability during load transients, as shown in Figure 6's ripple waveform. Ceramic capacitors ≥10μF may be used if paralleled with bulk capacitance to meet ESR and capacitance requirements simultaneously.

Does MP156GJ-P require an external VCC capacitor?

Yes - a 1–4.7μF ceramic capacitor must be placed between VCC and SOURCE pins. This capacitor sustains control circuit operation during switching cycles and is recharged by the internal HV current source from the DRAIN pin. The datasheet specifies 2.2μF as optimal for universal input; undersizing causes UVLO cycling and startup failure.

How does open-loop protection trigger and recover?

Open-loop protection activates when FB voltage falls below 60mV for >128 switching cycles (blanked during startup). The IC stops switching, discharges VCC to 2.4V via 16μA current source, then restarts once VCC drops below 2.4V and the HV regulator recharges it. Recovery time depends on VCC capacitor value and is calculated per equation on page 9 of the datasheet.

Is MP156GJ-P qualified for industrial temperature range?

Yes - its specified operating junction temperature is –40°C to +125°C, and thermal shutdown activates at 150°C. The SOIC8 variant (MP156GS) shares identical specs; both packages are rated for industrial use. Derating guidelines in Absolute Maximum Ratings (page 2) confirm 1W power dissipation at TA = +25°C for TSOT23-5.