Monolithic Power Systems Inc. HFC0511GS

Overview

HFC0511GS 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 130kHz nominal switching frequency, supports frequency foldback down to 27kHz, enters burst mode below 0.7V FB voltage, and integrates X-cap discharge functionality - enabling ultra-low no-load power consumption compliant with EuP Lot 6 in adapters for notebooks and smart phones.

For engineers reviewing the HFC0511GS datasheet, HFC0511GS pinout, HFC0511GS application, or HFC0511GS equivalent, key selection criteria include its HV-start capability (700V breakdown), adjustable over-power compensation (0.45μA/V), thermal shutdown at 150°C with 25°C hysteresis, and SOIC8-7A package compatibility with standard PCB layout practices.

Technical Context

The HFC0511GS implements a current-mode control architecture with integrated 25mV/μs slope compensation to prevent sub-harmonic oscillation in CCM operation above 50% duty cycle. Its dual-stage light-load management combines frequency foldback (active between 1.0V–1.8V FB) and burst mode (triggered at VBURL = 0.7V, exited at VBURH = 0.8V) to minimize switching losses across universal input (85–265VAC).

It features a programmable TIMER pin that unifies soft-start timing, frequency jitter modulation (±6.5% amplitude, 3.7ms period), OLP delay (40ms with 47nF), brown-out detection (HVON = 107V, HVOFF = 97V), and X-cap discharge sequencing (32-cycle detection → 16-cycle first discharge → repeated 48/16 cycles). The HV pin provides a 700V-rated start-up current source with 2.8mA typical supply at 400V.

Key Specifications

Pinout & Package

The HFC0511GS is housed in a SOIC8-7A package - an industry-standard 8-pin surface-mount outline with 1.27mm pitch, optimized for high-voltage isolation and thermal dissipation in compact flyback designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC28704DR and ICE2QS03G, the HFC0511GS uniquely integrates HV start-up, X-cap discharge, and tightly specified burst thresholds (0.7V/0.8V) - delivering lower component count and guaranteed <30mW no-load power without external circuitry.

Availability

HFC0511GS is available at Aetrix Electronics and suitable for AC/DC notebook adapters, smartphone charging systems, and offline battery chargers requiring stable component supply, long-term lifecycle support, and RoHS-compliant green-mode operation.

Supply support for HFC0511GS 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 HFC0511GS belongs to MPS's Green-Mode Flyback Controller product line, engineered specifically for ultra-low standby power in universal-input AC/DC converters targeting energy regulations like EuP Lot 6 and DOE Level VI.

FAQ

What is the minimum recommended VCC capacitor value for reliable brown-out detection?

A minimum 10µF VCC capacitor is recommended to ensure the VCC hold-up time exceeds half the AC input period (≈10ms at 50Hz). This guarantees robust brown-out detection during line sags, as the internal latch current (700µA typical) must sustain VCC above VCCSS (12V) long enough for the 40ms OLP timer to reset cleanly.

How does the HFC0511GS achieve EuP Lot 6 compliance without external X-cap discharge resistors?

The HFC0511GS uses its HV pin and TIMER pin to execute a sequenced X-cap discharge: after AC removal, it waits 32 TIMER cycles, then applies 16 cycles of HV current to initiate discharge, followed by repeated 48-cycle discharge/16-cycle detection windows until X-cap voltage falls below VCC. This eliminates continuous bleeder loss while meeting IEC62368-1 touch-current safety limits.

Can the over-power compensation be disabled for fixed-output applications?

Yes - over-power compensation is automatically disabled when FB voltage falls below 0.55V (VOPC(OFF)). For fixed-output designs where OLP consistency is less critical, this occurs naturally during light-load burst mode, effectively removing compensation influence without external intervention.

What is the purpose of the dual leading-edge blanking (LEB) times on the CS pin?

The HFC0511GS employs two LEB durations: 350ns for normal current limiting and 270ns for short-circuit protection. This allows precise rejection of transformer leakage spike noise during normal switching while enabling faster fault response during hard shorts - preventing MOSFET destruction without compromising steady-state stability.

Does the frequency jitter affect the accuracy of the OLP timer function?

No - the OLP timer uses the internal TIMER capacitor charged by a dedicated 10µA current source, independent of oscillator jitter. Its 40ms timeout (with 47nF capacitor) is unaffected by frequency modulation, ensuring consistent overload response regardless of jitter state or FB voltage level.

How is thermal shutdown behavior modified during fault conditions?

During thermal shutdown, the VCC UVLO lower threshold drops from 8.5V to 5.5V (VCCPRO), allowing the HV current source to recharge VCC even under latch conditions. This ensures the IC remains powered and can monitor temperature continuously, enabling auto-restart only when junction temperature falls below 125°C - not just VCC recovery.

What determines the maximum allowable output power in constant-voltage mode?

Maximum output power is set by the CS current-limit threshold (1.0V typical) and transformer turns ratio. The over-power compensation function adjusts the effective current limit based on HV voltage, narrowing the OLP point variation between 85VAC and 265VAC inputs to ±3% - critical for consistent power delivery across universal line ranges.