Monolithic Power Systems Inc. MP156GS

Overview

MP156GS 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 operates across -40°C to +125°C junction temperature-enabling compact, low-cost AC/DC conversion in home appliance standby supplies.

For engineers reviewing the MP156GS datasheet, MP156GS pinout, MP156GS application, or MP156GS equivalent, this page provides verified technical context on green-mode frequency foldback, peak-current compression, VCC UVLO hysteresis (250mV), OLP timer delay (170ms at 37kHz), and open-loop detection threshold (60mV).

Technical Context

The MP156GS implements primary-side regulation using internal sampling capacitor feedback to eliminate optocouplers. Its error amplifier samples FB voltage 6µs after MOSFET turn-off, enabling precise 2.55V ±100mV reference tracking across load and temperature.

Green-mode operation dynamically scales switching frequency and peak current limit (290mA typ.) downward under light load via minimum off-time control (18µs normal, soft-starting from 72µs) and ramp compensation that increases exponentially as load decreases-reducing no-load dissipation while maintaining regulation.

Key Specifications

Pinout & Package

MP156GS is housed in an 8-pin SOIC package with exposed pad connected to DRAIN for thermal enhancement. Pin 1 is VCC; pins 3 and 4 are SOURCE (common ground reference); pin 7 is DRAIN; pin 2 is FB; pins 5, 6, and 8 are NC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP157GS, MP156GS trades 150V breakdown margin for lower system cost and identical thermal performance in SOIC8; versus LNK304DG, it delivers 58% lower no-load power and eliminates external current sensing-reducing component count and layout sensitivity.

Availability

MP156GS is available at Aetrix Electronics and suitable for smart appliance standby supplies, white goods control boards, consumer electronics adapters, and industrial sensor node PSUs requiring stable component supply across multi-year production cycles.

Supply support for MP156GS 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 primary-side regulation, ultra-low standby power, and topology flexibility without optocouplers.

FAQ

What is the maximum recommended output power for MP156GS in SOIC8 package?

The MP156GS supports up to 4W output power in SOIC8 under typical conditions (T_A = 25°C, adequate copper area). Derating is required above 70°C ambient due to θ_JA = 96°C/W; at 85°C, maximum continuous output drops to ~2.8W to maintain T_J ≤ 125°C. Layout with thermal vias under the exposed DRAIN pad improves power handling.

Does MP156GS require an external VCC supply in all topologies?

Yes-MP156GS relies on an external VCC supply derived from the output or auxiliary winding. The internal HV current source only charges VCC during startup; sustained operation requires external bias (e.g., resistor from output to VCC with Zener clamp). This ensures stable regulation and enables <30mW no-load consumption.

How does the MP156GS implement open-loop protection without secondary feedback?

MP156GS detects open-loop failure by monitoring FB pin voltage: if V_FB falls below 60mV for >128 switching cycles (blanked during startup), the IC halts switching and initiates auto-restart. This threshold corresponds to loss of sampling capacitor charge-indicating broken feedback path or failed resistors-without requiring secondary-side components.

Can MP156GS be used in isolated flyback designs with primary-side regulation?

Yes-MP156GS supports flyback topology using primary-side regulation via auxiliary winding sampling. The FB pin senses reflected output voltage through a resistor divider on the auxiliary winding, eliminating optocoupler and TL431. Design requires careful turns ratio selection to ensure V_FB stays within 1.6–2.65V across line/load/temperature.

What is the purpose of the 350ns leading-edge blanking (LEB) function?

The 350ns LEB disables the current comparator immediately after MOSFET turn-on to suppress false triggering from parasitic ringing and di/dt-induced voltage spikes across the internal sense element. This ensures accurate peak-current limiting without requiring external RC snubbers-critical for stable operation in high-frequency, high-dV/dt flyback and boost converters.

How does frequency foldback improve light-load efficiency in MP156GS?

Frequency foldback reduces switching frequency as load decreases, directly lowering switching losses (proportional to f_SW). Simultaneously, peak-current compression lowers conduction losses. Together, they maintain >65% efficiency at 10% load-versus <45% for fixed-frequency controllers-making MP156GS compliant with stringent global standby power regulations.

Is MP156GS RoHS-compliant and lead-free?

Yes-MP156GS is fully RoHS-compliant and lead-free, meeting Directive 2011/65/EU. All MPS products adhere to JEDEC J-STD-020 moisture sensitivity level (MSL) 3 and undergo rigorous qualification per AEC-Q200 for industrial reliability. Full compliance documentation is available on the MPS Quality Assurance portal.