Monolithic Power Systems Inc. HFC0400GS-P

Overview

HFC0400GS-P from Monolithic Power Systems is a fixed-frequency current-mode flyback controller with integrated slope compensation, HV startup current source, and X-cap discharge function. It operates at 65kHz nominal switching frequency, supports frequency foldback down to 25kHz, enters burst mode below 0.32V FB, and achieves ≤35.26mW no-load power at 265VAC/50Hz - targeting medium-power AC/DC adapters for notebooks and smartphones.

For engineers reviewing the HFC0400GS-P datasheet, HFC0400GS-P pinout, HFC0400GS-P application, or HFC0400GS-P equivalent, key selection criteria include its 700V HV pin breakdown, 25kHz–65kHz adaptive frequency range, 0.95V current limit threshold, thermal shutdown with 25°C hysteresis, and SOIC8-7A package compatibility with standard flyback transformer designs.

Technical Context

HFC0400GS-P implements fixed-frequency current-mode control with built-in 25mV/µs slope compensation to prevent subharmonic oscillation in CCM operation above 50% duty cycle. Its HV pin provides 700V breakdown rating and enables brown-out detection (108V turn-on, 103V turn-off) plus programmable X-cap discharge via TIMER pin timing.

The controller integrates multiple protection mechanisms: timer-based OLP triggered at FB ≥3.7V after 50ms delay, latch-off OVP at VCC ≥25V for 26µs, short-circuit protection at CS ≥1.45V with 270ns blanking, and thermal shutdown at 150°C with auto-restart hysteresis. Burst mode activation is controlled by FB thresholds (0.32V entry, 0.46V exit).

Key Specifications

Pinout & Package

Package: SOIC8-7A - surface-mount, 8-pin, 150°C rated, RoHS-compliant package with exposed pad not present; compatible with standard reflow profiles and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-frequency flyback controller applications.

Compared with UCC28630DR and ICE2QS03G, HFC0400GS-P uniquely combines 700V HV startup, 25kHz foldback, burst mode, and certified X-cap discharge in one SOIC8-7A package - making it the only option meeting IEC 62368-1 and Energy Star Tier 2 for consumer AC/DC adapters.

Availability

HFC0400GS-P is available at Aetrix Electronics and suitable for AC/DC adapters, offline battery chargers, and LCD monitor power supplies requiring stable component supply, long-term lifecycle support, and certified low-noise performance.

Supply support for HFC0400GS-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.

HFC0400GS-P belongs to MPS's AC/DC flyback controller product line, engineered specifically for ultra-low standby power, integrated safety features, and simplified board-level design in consumer-grade offline power supplies.

FAQ

What is the maximum allowable no-load input power for HFC0400GS-P at 230VAC?

HFC0400GS-P achieves 32.40mW no-load power consumption at 230VAC/50Hz with 5V/0A and 16V/0A outputs, verified per typical performance characteristics on page 12 of Rev. 1.02 datasheet. This value assumes standard external components and PCB layout per MPS reference design MPQ2012.

How does the X-cap discharge function operate without external resistors?

Upon AC removal, HFC0400GS-P activates its internal HV current source after ~32 TIMER cycles, discharging the X-cap in 16-cycle bursts separated by 16-cycle detection windows. Total discharge time depends on X-cap value and line voltage but ensures V_X drops below V_CC (5.3V) before system restart, eliminating bleeder resistor losses.

Can HFC0400GS-P operate in continuous conduction mode (CCM)?

Yes - its built-in 25mV/µs slope compensation enables stable CCM operation even at duty cycles exceeding 50%, as confirmed in Section "Current-Mode Operation with Slope Compensation" (page 14). This allows optimized transformer sizing and reduced RMS current in universal-input designs.

What is the purpose of the two leading-edge blanking (LEB) times?

HFC0400GS-P uses 350ns LEB1 for normal current sensing and 270ns LEB2 specifically for short-circuit protection. The shorter LEB2 ensures rapid SCP response (<1µs delay) while avoiding false triggering from MOSFET switching noise during normal operation.

Does HFC0400GS-P require an external VCC capacitor?

Yes - a minimum 10µF VCC capacitor is recommended (page 18), sized using equation (4) to sustain operation during brown-out events. The capacitor must handle ripple current from the auxiliary winding and maintain VCC within 8.0–14.5V UVLO window during all load and line conditions.

How is overload protection (OLP) differentiated from over-voltage protection (OVP)?

OLP is timer-based: FB ≥3.7V for 50ms triggers shutdown. OVP is voltage-latched: VCC ≥25V for 26µs forces full latch-off until VCC drops below 2.5V. OLP protects against sustained overloads; OVP safeguards against regulator failure or feedback loop open-circuit faults.

Is the SOIC8-7A package thermally enhanced?

No - SOIC8-7A is a standard plastic SOIC package with θ_JA = 96°C/W and θ_JC = 45°C/W (page 3). It lacks an exposed thermal pad; thermal design must rely on copper pour and airflow. For >15W designs, consider heatsinking the DRV and CS traces per MPS AN-107 guidelines.