Monolithic Power Systems Inc. HFC0100HS-LF-P

Overview

HFC0100HS-LF-P from Monolithic Power Systems is a peak current mode quasi-resonant (QR) controller IC for offline flyback SMPS, featuring integrated high-voltage startup current source (700V HV pin), valley-switching detection (40–70mV VVSD threshold), burst-mode operation (0.5V/0.7V FB thresholds), and comprehensive protection including thermal shutdown (150°C), VCC UVLO (8V/11.8V), OVP (6V), and OLP (3.7V). It targets low-standby-power AC/DC adapters for consumer electronics.

For engineers reviewing the HFC0100HS-LF-P datasheet, HFC0100HS-LF-P pinout, HFC0100HS-LF-P application, or HFC0100HS-LF-P equivalent, key selection criteria include QR valley-sensing timing (100–200ns tVSD), minimum off-time limit (7.8μs), internal soft-start (2.4ms), 250ns leading-edge blanking, and SOIC-8 package compatibility with auxiliary-winding-based OVP and optocoupler feedback.

Technical Context

The HFC0100HS-LF-P implements discontinuous conduction mode (DCM) QR control using valley detection on the VSD pin to trigger MOSFET turn-on at minimum drain-source voltage, reducing switching loss and EMI. Its internal 700V-rated HV pin enables direct rectified-line startup without auxiliary winding during initial power-up.

Operation includes active burst mode below 0.5V FB (restarting at 0.7V), auto-retry UVLO/OLP/OTP, and latch-off OVP triggered by 6V VSD plateau sampling with 3.5μs blanking. The controller enforces a 7.8μs minimum off-time to cap frequency ≤150kHz per EN55022 requirements.

Key Specifications

Pinout & Package

Package: SOIC-8 (3.9mm × 4.9mm, 1.27mm pitch), RoHS-compliant, lead-free, halogen-free.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quasi-resonant controller applications.

Compared with NCP1342DR2G and ICE2QS03G, the HFC0100HS-LF-P uniquely combines 700V HV startup, SOIC-8 footprint, and VSD-based OVP in a discrete-controller format-enabling higher power density and simpler transformer design than integrated solutions, while avoiding external startup components required by NCP1342.

Availability

HFC0100HS-LF-P is available at Aetrix Electronics and suitable for smartphone chargers, LCD TV standby supplies, inkjet printer power modules, and refrigerator control board SMPS requiring stable component supply and long-term lifecycle support.

Supply support for HFC0100HS-LF-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 HFC0100 belongs to MPS's Quasi-Resonant Controller product line, engineered specifically for high-efficiency, low-standby-power offline flyback converters targeting consumer, computing, and white-goods applications.

FAQ

What is the purpose of the NC pin (Pin 3) on the HFC0100HS-LF-P?

Pin 3 is a no-connect terminal reserved solely to increase creepage distance between HV (Pin 4) and VCC (Pin 2) for reinforced isolation compliance in AC/DC power supplies. It must remain unconnected on the PCB and should not be tied to ground, VCC, or any other net per MPS design guidelines and safety certification requirements.

How does the HFC0100HS-LF-P implement over-voltage protection without a direct output voltage sense?

The HFC0100HS-LF-P monitors the auxiliary winding voltage on the VSD pin. Since the auxiliary winding voltage is proportional to the output voltage (VOUT × NAUX/NSEC), a 6V threshold on VSD triggers latch-off OVP. This eliminates the need for secondary-side voltage dividers or TL431 circuits, simplifying isolated feedback while maintaining accurate output overvoltage detection.

Can the HFC0100HS-LF-P operate without an auxiliary winding?

No. The VSD pin is mandatory for valley detection, OVP, and minimum off-time enforcement. Without an auxiliary winding, the controller cannot detect drain voltage valleys, resulting in hard switching, excessive EMI, and potential failure. The datasheet specifies auxiliary winding connection as fundamental to all operating modes-including burst, QR, and fault protection.

What is the function of the internal 250ns leading-edge blanking (LEB) on the CS pin?

The 250ns LEB disables the current comparator input immediately after DRIVE turns on, blocking the high dv/dt-induced current spike from the MOSFET's parasitic capacitance and PCB trace inductance. This prevents premature current-limit triggering during turn-on, ensuring accurate peak current sensing and stable power delivery across line and load variations.

How does burst mode reduce standby power, and what sets its entry/exit thresholds?

Burst mode reduces standby power by pausing switching cycles when output load drops below ~5%. The controller stops switching when FB falls to 0.5V (VBURL), allowing output voltage to decay until FB rises to 0.7V (VBURH), at which point normal QR operation resumes. This gated cycling cuts both switching and gate-drive losses, achieving <30mW no-load consumption compliant with DOE VI and CoC Tier 2.

Is the HFC0100HS-LF-P compatible with synchronous rectification controllers?

Yes-the HFC0100HS-LF-P is designed to interface with external synchronous rectification (SR) controllers such as the MP6908 or SR086. Its DRIVE output timing and valley detection enable precise SR FET turn-on, while FB-based current limiting ensures coordinated primary/secondary regulation. No modifications to the HFC0100HS-LF-P circuit are needed beyond adding the SR controller and associated gate drive components.

What thermal protection behavior occurs if junction temperature exceeds 150°C?

When die temperature reaches 150°C, the HFC0100HS-LF-P initiates thermal shutdown (TSD), halting all switching and gate drive. The device remains latched off until junction temperature falls to 100°C (50°C hysteresis), at which point it automatically restarts. This auto-retry behavior protects against permanent damage during sustained overload or poor heatsinking without requiring external reset circuitry.