Monolithic Power Systems Inc. HFC0400GS-Z

Overview

HFC0400GS-Z from Monolithic Power Systems is a fixed-frequency current-mode flyback controller in SOIC8-7A package, featuring built-in slope compensation, 65kHz nominal switching frequency, 25kHz minimum foldback frequency, burst-mode operation for ultra-low no-load power (≤35.26mW at 265VAC), and integrated X-cap discharge function. It targets medium-power AC/DC adapters requiring high light-load efficiency and safety-compliant standby performance.

For engineers reviewing the HFC0400GS-Z datasheet, HFC0400GS-Z pinout, HFC0400GS-Z application, or HFC0400GS-Z equivalent, key selection criteria include its HV-startup architecture, TIMER-pin-based protection latching, FB-triggered burst/foldback thresholds (0.32V/0.46V and 1.0V/1.8V), and clamped DRV output (13.4V) enabling direct MOSFET drive without external level-shifting.

Technical Context

HFC0400GS-Z implements fixed-frequency current-mode control with programmable slope compensation (25mV/µs) to stabilize CCM operation beyond 50% duty cycle. Its dual-stage light-load management-frequency foldback down to 25kHz followed by burst mode-minimizes switching and conduction losses across 0–100% load range.

The controller integrates a high-voltage (700V) startup current source with brown-out detection (HVON=108V, HVOFF=103V), VCC UVLO with hysteresis (8.0V/14.5V), and multi-level fault handling: timer-based OLP (3.7V FB threshold, 50ms delay), latch-off OVP (25V, 26µs), and short-circuit protection (1.45V CS threshold, 270ns LEB).

Key Specifications

Pinout & Package

Package: SOIC8-7A (exposed pad not present; standard 8-pin SOIC with 7 functional pins and 1 NC pin - Pin 7 is not connected per MPS datasheet Rev. 1.02, p.6).

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, HFC0400GS-Z uniquely combines ultra-low no-load power (<35mW), integrated X-cap discharge, and fixed-frequency jittering - making it optimal for space-constrained, regulatory-driven AC/DC adapters where BOM count and standby loss are primary constraints.

Availability

HFC0400GS-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 compliance with global energy standards.

Supply support for HFC0400GS-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.

HFC0400GS-Z belongs to MPS's high-efficiency flyback controller product line, designed specifically for ultra-low standby power in universal-input, medium-power AC/DC converters targeting consumer and computing applications.

FAQ

What is the maximum allowable HV pin voltage for continuous operation?

The HV pin has a 700V breakdown rating and supports continuous operation up to 700V. Absolute maximum rating is -0.7V to +700V relative to GND. Operation above 600V requires careful PCB layout to avoid creepage/clearance violations and ensure reliable brown-out detection at 103–108V thresholds.

How does the X-cap discharge function activate after AC removal?

After AC disconnection, the IC waits ~32 TIMER cycles (~11ms at 65kHz), then applies HV current for 16 cycles (~5.5ms) to discharge the X-cap. It repeats 48-cycle discharge/16-cycle detect cycles until X-cap voltage drops to VCC level, eliminating need for permanent bleed resistors.

Can the HFC0400GS-Z operate in continuous conduction mode (CCM)?

Yes - its internal 25mV/µs slope compensation stabilizes CCM operation even at duty cycles exceeding 50%, enabling higher power density and lower RMS currents in universal-input designs without external compensation components.

What is the purpose of the two leading-edge blanking (LEB) times?

LEB1 (350ns) suppresses MOSFET turn-on spikes on CS for normal current sensing; LEB2 (270ns) provides shorter blanking during short-circuit events to enable faster SCP response while maintaining noise immunity during normal operation.

How is thermal shutdown implemented and what is its hysteresis?

Thermal shutdown activates at 150°C junction temperature and auto-restarts when temperature falls to 125°C, yielding 25°C hysteresis. During TSD, VCC UVLO lower threshold drops from 8.0V to 5.3V to sustain internal bias during cooling.

Is the SOIC8-7A package lead-free and RoHS compliant?

Yes - HFC0400GS-Z is lead-free, halogen-free, and fully compliant with the RoHS directive. MPS confirms green status per its Quality Assurance documentation, with JEDEC-standard MSL 3 moisture sensitivity rating.

What determines the frequency jitter period and how is it set?

The jitter period (τjitter = 3.7ms typical) is set by the TIMER pin capacitor value and internal 10µA charge/discharge current. With CTIMER = 47nF, the 2.8V–3.2V triangular waveform yields ~270Hz modulation - optimized to exceed spectrum analyzer RBW while staying below control-loop crossover.