Monolithic Power Systems Inc. HFC0300HS-LF

Overview

HFC0300HS-LF from Monolithic Power Systems is a variable off-time, current-mode flyback controller IC designed for universal-input AC/DC SMPS. It implements fixed-peak-current control with frequency foldback (65 kHz max → <20 kHz light-load), peak-current compression to suppress transformer acoustic noise, active burst mode (VBURH = 3.2 V, VBURL = 3.1 V), and integrated high-voltage startup (700 V HV pin). It targets compact, high-efficiency offline adapters and battery chargers.

For engineers reviewing the HFC0300HS-LF datasheet, HFC0300HS-LF pinout, HFC0300HS-LF application, or HFC0300HS-LF equivalent, key selection criteria include its SOIC-7 package, 8.2–20 V VCC operating range, 200 ns internal leading-edge blanking, thermal shutdown with 25°C hysteresis, and OVP latch-off at 24 V with 3.0 V reset threshold.

Technical Context

The HFC0300HS-LF uses a voltage-controlled oscillator architecture where the FSET pin capacitor (charged by 28 µA current source) sets maximum frequency, while COMP feedback voltage dynamically adjusts off-time to regulate output. Its fixed-peak-current sensing (V_CS limit = 0.5 V) enables boundary conduction mode (BCM) operation across universal input (85–265 VAC).

Protection logic integrates timer-based overload detection (74 ms delay at C_FSET = 330 pF), short-circuit shutdown (V_CS > 1.0 V), and VCC overvoltage latching (24 V trip, 3.0 V release). Startup relies on internal 700 V HV current source until VCC reaches 11.7 V, then transitions to auxiliary winding supply.

Key Specifications

Pinout & Package

Package: SOIC-7 (7-pin small-outline integrated circuit, surface-mount, RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC28704DR and ICE2QS03G, the HFC0300HS-LF delivers superior light-load efficiency via integrated burst mode and peak-current compression, eliminates external HV startup components, and provides tighter OVP reset control-making it optimal for space-constrained, low-noise, high-reliability offline supplies.

Availability

HFC0300HS-LF is available at Aetrix Electronics and suitable for USB-C wall adapters, smart home IoT power supplies, medical auxiliary PSUs, and industrial sensor transmitters requiring stable component supply, RoHS compliance, and long-term lifecycle support.

Supply support for HFC0300HS-LF 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, and global manufacturing partnerships.

The HFC0300 belongs to MPS's offline AC/DC controller product line, engineered specifically for high-efficiency, low-noise, and compact flyback converters targeting consumer, industrial, and medical power applications.

FAQ

What is the purpose of the HV pin on the HFC0300HS-LF?

The HV pin provides a 700 V-rated input for the internal high-voltage startup current source (2 mA typical), enabling direct connection to the rectified AC line. This eliminates the need for an external high-voltage resistor network, reducing standby power and component count. The current source automatically disables once VCC reaches 11.7 V.

How does the HFC0300HS-LF achieve low no-load power consumption?

It enters active burst mode when COMP voltage exceeds 3.2 V, disabling switching entirely until COMP falls below 3.1 V. Combined with frequency foldback and peak-current compression, this reduces measured no-load loss to 74.4 mW at 90 VAC and <100 mW at 265 VAC-meeting stringent global energy standards.

Can the HFC0300HS-LF operate in continuous conduction mode (CCM)?

Yes-it supports CCM, DCM, and boundary conduction mode (BCM) depending on transformer design and current-sense resistor value. The fixed 0.5 V CS threshold allows precise peak-current setting; CCM operation requires selecting R_sense such that I_peak exceeds the BCM-calculated value per application note equations (3)–(6).

What protection features are integrated into the HFC0300HS-LF?

It integrates thermal shutdown (150 °C trip, 125 °C release), VCC under-voltage lockout (8.2 V ON / 11.7 V OFF), over-voltage protection (24 V latch, 3.0 V reset), timer-based overload protection (74 ms delay), short-circuit protection (1.0 V CS threshold), and over-voltage protection on VCC pin with 20 µs filtering.

How is switching frequency adjusted in real time?

Frequency is controlled by the voltage on the FSET pin, which is charged by a 28 µA current source and compared against the COMP feedback voltage. As COMP rises (lighter load), the FSET capacitor charges slower, extending off-time and lowering frequency-enabling natural EMI spreading without external frequency modulation circuitry.

Is an external ramp compensation circuit required?

Ramp compensation is required only for CCM operation with duty cycle >0.5 to prevent subharmonic oscillation. The recommended circuit (R1=510 kΩ, R2=33 pF, R3=1 kΩ, C1=30 kΩ) injects slope-compensated current into the CS node, with compensation rate calculated per equation (10) in the datasheet.

What is the function of the 200 ns leading-edge blanking (LEB) feature?

The internal 200 ns LEB disables the current-sense comparator immediately after DRV turn-on, preventing false triggering from parasitic ringing at the MOSFET drain. This ensures accurate peak-current detection and stable operation even with high dV/dt switching waveforms.