Monolithic Power Systems Inc. MP023GS

Overview

MP023GS from Monolithic Power Systems is a primary-side, offline flyback controller delivering precise constant-voltage (CV) and constant-current (CC) regulation without optocoupler or secondary feedback. It integrates a 700V high-voltage start-up current source, supports programmable cable compensation via the CP pin, features variable off-time peak current control for DCM operation, and achieves ≤30mW no-load power consumption. It targets low-power AC/DC adapters for handheld electronics.

For engineers reviewing the MP023GS datasheet, MP023GS pinout, MP023GS application, or MP023GS equivalent, key selection considerations include its SOIC8-7A package, HV pin's 700V breakdown rating, FB reference voltage of 3.96V ±6mV, programmable CS-based sampling time (2.5–9.2μs), and integrated OVP/OLP/OTP/OCkP/VCC UVLO protection.

Technical Context

The MP023GS implements primary-side regulation using auxiliary winding voltage sensing at the FB pin with programmable sampling timing (tFBS-Min to tFBS-Max) to compensate for diode forward-drop variation across load conditions. Its variable off-time control modulates switching frequency (72–105Hz min, up to ~150kHz typical) to maintain CV or CC output while operating strictly in discontinuous conduction mode (DCM) via zero-current detection (ZCD threshold: 55–145mV).

Current limiting is set by VLimit-Max (464–496mV) in CC mode and dynamically adjusted in CV mode via frequency modulation; maximum on-time (tONmax = 22–50μs) prevents latch-up during CS short. Cable compensation is enabled only when CP is connected to a 1μF capacitor-activating a proportional current-sink in FB that adjusts the output voltage divider's effective ratio based on VCP (e.g., 1.6V at 500mV limit, 0.4 duty).

Key Specifications

Pinout & Package

MP023GS is housed in a SOIC8-7A package - an industry-standard 8-pin surface-mount outline with exposed pad omitted, optimized for compact flyback transformer designs and thermal performance in low-power adapters.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar primary-side CC/CV flyback controller applications.

Compared with MP021GS, MP023GS adds critical cable compensation and flexible sampling timing for tighter CV regulation across variable loads; versus UCC28730, it simplifies design with integrated HV start-up and deterministic ZCD threshold, reducing validation effort for cost-sensitive consumer adapters.

Availability

MP023GS is available at Aetrix Electronics and suitable for USB wall adapters, smartphone charging supplies, and appliance standby power systems requiring stable component supply, RoHS-compliant sourcing, and long-term production continuity.

Supply support for MP023GS 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 core expertise in DC/DC conversion, LED drivers, and AC/DC controllers.

The MP023GS belongs to MPS's primary-side regulated flyback controller product line, designed specifically for cost-sensitive, low-power (<30W) offline adapters where optocoupler elimination, low no-load power, and cable compensation are critical system requirements.

FAQ

What is the function of the CP pin on MP023GS?

The CP pin provides output cable compensation by generating a DC voltage (e.g., 1.6V at 500mV current limit) proportional to output current, which sinks current from the FB voltage divider to raise the effective output voltage setpoint. This compensates for IR drop across USB cables - but only when CP is connected to a 1μF capacitor; adding any resistor disables this function.

How does MP023GS achieve primary-side constant current regulation without secondary sensing?

MP023GS infers output current from primary-side parameters: it fixes peak primary current (via VLimit-Max at CS) and controls secondary diode conduction time (D_S-Max) through CP pin configuration. The relationship I_OUT = (N_P/N_S) × I_PKS × (1−D_S-Max)/2 is enforced by internal timing logic, eliminating need for secondary shunt or Hall-effect sensors.

Can MP023GS operate with universal AC input (90–264VAC)?

Yes - the 700V HV pin withstands rectified line voltages up to 375VDC (265VAC), and the VCC UVLO range (8.2–20.0V) accommodates wide auxiliary winding voltage swings. Designers must select transformer turns ratio and bulk capacitor values to ensure minimum V_DC exceeds the expression in Equation (11) across full input range.

What protection features are integrated into MP023GS?

MP023GS integrates six protections: VCC under-voltage lockout (UVLO), over-voltage protection (OVP) triggered at FB >5.96V, open-circuit protection (OCkP) detecting missing FB signal, overload protection (OLP) after 128 cycles of FB <1.38V, over-temperature protection (OTP) at 140°C, and internal maximum on-time (tONmax) limiting to prevent latch-up during CS faults.

Is MP023GS compatible with synchronous rectification controllers like MP6906?

Yes - MP023GS is fully compatible with MPS's MP6906 synchronous rectifier controller. The MP6906 replaces the secondary Schottky diode, driven by the same transformer auxiliary winding used for MP023GS feedback, enabling efficiency gains of 2–3% in 5–12V output designs without modifying the primary-side control loop.

What is the minimum external component count required for a functional MP023GS design?

A minimal working MP023GS flyback requires only seven components: one primary MOSFET, one current-sense resistor (CS), one gate drive resistor (DRV), one VCC decoupling capacitor (0.1μF), one FB voltage divider (two resistors), one CP capacitor (1μF for cable comp), and the transformer with auxiliary winding - no optocoupler, TL431, or secondary-side references needed.