Monolithic Power Systems Inc. HFC0511GS-P

Overview

HFC0511GS-P 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 27 kHz minimum switching frequency under light load, burst-mode operation for ≤30 mW no-load consumption, and integrated X-cap discharge. Used in notebook adapters and LCD TV standby power stages.

For engineers reviewing the HFC0511GS-P datasheet, HFC0511GS-P pinout, HFC0511GS-P application, or HFC0511GS-P equivalent, key selection criteria include its 700 V HV pin rating, adjustable over-power compensation, thermal shutdown with 25°C hysteresis, and SOIC8-7A package compatibility with universal input (85–265 VAC) designs.

Technical Context

The HFC0511GS-P implements current-mode control with 25 mV/μs internal slope compensation to prevent sub-harmonic oscillation in CCM operation above 50% duty cycle. Its frequency foldback reduces switching frequency from 130 kHz down to 27 kHz as FB voltage drops below 1.8 V, freezing peak current at 0.68 V on CS.

Burst mode activates when FB falls below 0.7 V, halting DRV output until FB rises above 0.8 V; this enables <30 mW no-load power. The TIMER pin integrates soft-start timing (via external capacitor), OLP delay (40 ms with 47 nF), brown-out detection, and X-cap discharge sequencing (32-cycle delay + 16/48-cycle discharge cycles).

Key Specifications

Pinout & Package

Available in SOIC8-7A package (7-pin variant with pin 7 omitted; pin numbering follows standard SOIC-8 layout). Thermal resistance θ_JA = 96°C/W on 4-layer PCB.

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, the HFC0511GS-P uniquely integrates X-cap discharge, 700 V HV rating, and burst-mode tuning for sub-30 mW no-load performance - making it optimal for safety-certified, low-standby-power flyback designs.

Availability

HFC0511GS-P is available at Aetrix Electronics and suitable for AC/DC adapters, LCD TV standby supplies, and offline battery chargers requiring stable component supply, long-term lifecycle support, and RoHS-compliant green-mode operation.

Supply support for HFC0511GS-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 focus on efficiency, integration, and reliability in power conversion.

The HFC0511GS-P belongs to MPS's green-mode flyback controller product line, engineered specifically for ultra-low no-load power, universal AC input compatibility, and safety-critical discharge functions in consumer and industrial offline power supplies.

FAQ

What is the maximum allowable input voltage on the HV pin?

The HV pin is rated for continuous operation up to 700 V, with breakdown voltage guaranteed at 700 V (min) and 790 V (max). This allows direct connection to rectified universal AC mains (up to 375 VDC peak) with margin for transients and surges, eliminating need for external HV divider or startup resistor networks.

How does the X-cap discharge function operate without increasing standby power?

The HFC0511GS-P activates its internal HV current source only after detecting AC removal - initiating a timed sequence (32-cycle wait → 16-cycle discharge → 16-cycle detect → 48-cycle discharge) that fully discharges X-capacitors without continuous bleeder current. This eliminates the 0.5–1 W standby loss typical of fixed-resistor discharge paths.

Can the burst-mode entry and exit thresholds be adjusted externally?

No - VBURL (0.7 V) and VBURH (0.8 V) are internally fixed thresholds with no external adjustment. However, the FB node's DC level is set by the optocoupler feedback network; selecting appropriate resistor values on the secondary side allows precise control of the actual burst transition points relative to output voltage regulation.

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

TLEB1 (350 ns) applies during normal current limiting to ignore switch-node ringing; TLEB2 (270 ns) activates only during short-circuit protection to allow faster fault response. This dual-blanking scheme prevents false OCP triggering under normal operation while ensuring rapid SCP activation when VCS exceeds 1.47 V.

Does the HFC0511GS-P support continuous conduction mode (CCM) operation?

Yes - its internal 25 mV/μs slope compensation stabilizes current-mode control above 50% duty cycle, enabling reliable CCM operation across universal input ranges. This avoids sub-harmonic oscillation and supports higher power density designs with lower RMS currents in the primary winding.

How is over-power compensation calibrated for varying input voltages?

Over-power compensation injects a current (I_OPC) into the CS node proportional to HV voltage (K_OPC = 0.45 μA/V). By selecting the series resistor between CS and current-sense resistor, designers adjust how much this current offsets the sensed voltage - narrowing OCP variation from ±15% to ±5% across 85–265 VAC input range.

What happens to the DRV output during thermal shutdown?

During thermal shutdown, DRV is forced low and remains latched off until junction temperature falls below 125°C. Unlike hiccup mode, this is an auto-restart behavior with hysteresis - no external reset is required, and VCC UVLO threshold drops from 8.5 V to 5.5 V to sustain operation during fault recovery.