Monolithic Power Systems Inc. HF500GS-7-P

Overview

HF500GS-7-P from Monolithic Power Systems is a fixed-frequency, current-mode flyback regulator IC integrating a 700V/12Ω MOSFET and full control logic for offline AC/DC power supplies. It delivers up to 7W output in open-frame designs at 230Vac, supports self-supply without auxiliary winding, implements frequency jittering (±6.5% amplitude), and features timer-based overload protection with over-power line compensation. It targets low-cost, compact adapter and standby power applications.

For engineers reviewing the HF500GS-7-P datasheet, HF500GS-7-P pinout, HF500GS-7-P application, or HF500GS-7-P equivalent, key selection criteria include its integrated 700V MOSFET, SOIC8-7B package, self-supply capability, burst-mode operation down to 0.18V current-limit threshold, and input-voltage-independent OLP via B/O pin compensation.

Technical Context

The HF500GS-7-P operates in fixed-frequency current-mode control with built-in slope compensation (18–31 mV/μs) to prevent subharmonic oscillation above 50% duty cycle in CCM. Its oscillator runs at 65kHz nominal with ±6.5% jitter modulation period of 3.7ms when CTIMER = 47nF.

It implements three load-dependent operating modes: fixed-frequency with jitter at medium/heavy loads; frequency foldback down to 25kHz at light load (VFB < 1.8V); and burst mode below VFB = 0.7V, where switching halts until VFB rises above 0.8V. Over-power compensation adjusts current limit based on B/O voltage (0–247mV offset), decoupling OLP from input line variation.

Key Specifications

Pinout & Package

HF500GS-7-P is housed in a SOIC8-7B package - an industry-standard 8-pin surface-mount outline with one pin (Pin 3) omitted to support high-voltage creepage between DRAIN and GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP6004GQ-Z and UCC28704DR, the HF500GS-7-P uniquely combines self-supply, over-power line compensation, and frequency jitter in a single SOIC8-7B package - simplifying universal-input adapter design while ensuring consistent overload behavior and EMI compliance without auxiliary components.

Availability

HF500GS-7-P is available at Aetrix Electronics and suitable for home appliance power supplies, universal-input adapters, and industrial auxiliary power systems requiring stable component supply, long-lifecycle availability, and RoHS-compliant sourcing.

Supply support for HF500GS-7-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, and global manufacturing partnerships.

The HF500GS-7-P belongs to MPS's HF-series fixed-frequency flyback controllers, engineered specifically for cost-sensitive, low-power offline AC/DC conversion with integrated HV MOSFET and self-supply architecture.

FAQ

What is the maximum continuous output power achievable with HF500GS-7-P at 230Vac input?

At 230Vac ±15% in an open-frame design at 50°C ambient, HF500GS-7-P delivers up to 7W continuous output power. This rating assumes proper heatsinking, SOIC8-7B thermal resistance (θJA = 85°C/W), and junction temperature maintained below 125°C. Output power drops to 6.5W in enclosed non-ventilated adapters due to reduced thermal dissipation.

How does the self-supply function eliminate the need for an auxiliary winding?

The HF500GS-7-P integrates a high-voltage current source connected to the DRAIN pin, drawing startup current directly from the rectified AC bus. Once VCC reaches 12V, the internal source disables and the IC runs from VCC; if VCC falls below 11.5V, the source re-enables. This cycle sustains operation without auxiliary winding, reducing BOM count and transformer complexity.

Can HF500GS-7-P operate safely without input brown-in/out functionality?

Yes - pulling the B/O pin above 6V (VDIS = 5.4–6.6V) disables brown-in/out, input OVP, and over-power compensation. In this configuration, the IC starts immediately upon VCC reaching 11.5V and relies solely on VCC UVLO and internal protections. This simplifies design when line monitoring is unnecessary or handled externally.

What is the purpose of the TIMER pin's dual role in soft-start and overload protection?

The TIMER pin serves three functions: (1) soft-start ramp generation (1V → 1.75V), limiting inrush current; (2) frequency jitter modulation via triangular waveform comparison; and (3) OLP timing using a 16-cycle counter triggered when FB exceeds 3.7V. External capacitor value (e.g., 47nF) sets both soft-start duration and OLP delay (32ms typical), enabling coordinated startup and fault response.

How does over-power compensation maintain consistent overload protection across input voltage variations?

Over-power compensation adds a B/O-voltage-dependent offset (0–247mV) to the internal current-sense threshold. Since B/O voltage scales with input line voltage, the added offset counteracts the natural increase in primary current at higher input voltages - ensuring the OLP trip point remains fixed at ~7W regardless of whether input is 85Vac or 265Vac.

What thermal protection behavior occurs during sustained overload?

Under sustained overload, HF500GS-7-P first enters timer-based OLP (latching after 32ms), then triggers thermal shutdown if junction temperature exceeds 150°C. The device latches off until VCC drops below 2.5V (VCCLATCH), requiring power cycle recovery. Thermal hysteresis (25°C) ensures restart only after die cools to ≤125°C, preventing thermal cycling damage.