Monolithic Power Systems Inc. HFC0500GS-Z

Overview

HFC0500GS-Z from Monolithic Power Systems is a fixed-frequency current-mode flyback controller with internal slope compensation, designed for medium-power offline AC/DC power supplies. It delivers 65 kHz nominal switching frequency, supports frequency foldback down to 25 kHz, enters burst mode below 0.7 V FB voltage, and achieves ≤79 mW no-load power consumption at 265 VAC. It integrates HV startup, X-cap discharge, and programmable OLP for notebook adapters and smart phone chargers.

For engineers reviewing the HFC0500GS-Z datasheet, HFC0500GS-Z pinout, HFC0500GS-Z application, or HFC0500GS-Z equivalent, key selection criteria include its ultra-low standby power (EuP Lot 6 compliant), adjustable overpower compensation via CS pin, thermal shutdown with 25°C hysteresis, and SOIC8-7A package compatibility with board-level EMI mitigation requirements.

Technical Context

HFC0500GS-Z implements fixed-frequency current-mode control with 25 mV/μs internal slope compensation to prevent subharmonic oscillation in CCM operation above 50% duty cycle. Its dual-stage light-load management-frequency foldback (21–30 kHz) followed by burst mode-reduces switching losses while maintaining regulation.

The controller features integrated high-voltage (700 V) startup current source with brown-out detection (HVON = 107 V typ., HVOFF = 97 V typ.), X-cap discharge triggered after 32 TIMER cycles upon AC removal, and latched fault protection on TIMER pin (VTIMER(LATCH) = 1 V, TLATCH = 12 μs) for external OVP/OTP.

Key Specifications

Pinout & Package

Package: SOIC8-7A - thermally enhanced 8-pin surface-mount package with exposed pad (θJA = 96°C/W, θJC = 45°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC28632DR and ICE2QS03G, HFC0500GS-Z uniquely combines fixed-frequency stability, integrated X-cap discharge, and adjustable overpower compensation - delivering lower system-level BOM cost, guaranteed EuP Lot 6 standby performance, and simplified safety certification for universal-input AC/DC designs.

Availability

HFC0500GS-Z 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 RoHS-compliant green-mode operation.

Supply support for HFC0500GS-Z 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 over 20 years of expertise in DC/DC, AC/DC, and motor driver solutions.

HFC0500GS-Z belongs to MPS's green-mode flyback controller product line, engineered specifically for ultra-low no-load power consumption and integrated safety functions in universal-input offline power supplies.

FAQ

What is the minimum recommended VCC capacitor value for reliable start-up?

A minimum 10 µF VCC capacitor is recommended per the datasheet. This ensures sufficient hold-up time during brown-out detection (VCCOFF to VCCSS window), maintains >50% of AC input period for reliable HV monitoring, and supports stable operation under worst-case ICC(noswitch) = 700 µA latch-mode current draw.

How does the X-cap discharge function eliminate external bleed resistors?

HFC0500GS-Z uses its HV pin to activate an internal current source only after AC removal - initiating a timed 16-cycle discharge pulse, followed by 16-cycle re-detection and 48-cycle secondary discharge until X-cap voltage drops to VCC level. This replaces constant-loss external resistors with intelligent, event-triggered discharge.

Can the burst mode threshold be adjusted externally?

No - burst entry (VBURL = 0.7 V typ.) and exit (VBURH = 0.8 V typ.) thresholds are internally fixed. However, the effective burst point can be tuned indirectly via opto-coupler gain and feedback divider ratio, which set the FB voltage corresponding to specific output load conditions.

What is the purpose of the two leading-edge blanking times (TLEB1/TLEB2)?

TLEB1 = 350 ns disables the current comparator during MOSFET turn-on to ignore parasitic ringing on CS; TLEB2 = 270 ns applies during short-circuit events to enable faster SCP response. This dual-blanking scheme prevents false OCP triggering while preserving robust fault detection.

Does the HFC0500GS-Z support continuous conduction mode (CCM) operation?

Yes - its 25 mV/μs internal slope compensation stabilizes current-mode control up to 75% duty cycle, enabling reliable CCM operation across universal input ranges without external compensation networks or risk of subharmonic oscillation.

How is overload protection (OLP) implemented without secondary-side sensing?

OLP uses the FB pin: when output overloads, opto-coupler current drops, raising FB voltage. Once FB exceeds VOLP = 3.7 V, a 40 ms timer (CTIMER = 47 nF) begins counting. If FB remains above 3.7 V for the full duration, DRV is latched off - providing primary-side OLP without auxiliary windings.

What is the maximum allowable HV pin voltage during normal operation?

The HV pin has a 700 V absolute maximum rating, with typical breakdown at 790 V. During normal operation, it connects directly to the rectified AC line (≤375 V peak at 265 VAC), well within safe margin. The internal current source turns off once VCC reaches 15.5 V, isolating HV from active biasing.