Monolithic Power Systems Inc. HF900GS-P

Overview

HF900GS-P from Monolithic Power Systems is a 900V offline flyback switching regulator IC with integrated high-voltage MOSFET, peak-current-mode control, programmable switching frequency up to 300kHz, and burst-mode operation for <100mW standby power. It delivers stable AC/DC conversion in smart meters and industrial controls operating on unstable AC grids.

For engineers reviewing the HF900GS-P datasheet, HF900GS-P pinout, HF900GS-P application, or HF900GS-P equivalent, key selection criteria include its 900V drain breakdown, VCC UVLO hysteresis (3.6V typ), FB-triggered burst mode (0.5V entry / 0.7V exit), OTP threshold (150°C), and FSET-programmable jittering frequency.

Technical Context

The HF900GS-P implements peak-current-mode control with internal slope compensation (40mV/μs) and dual leading-edge blanking (350ns for current sense, 300ns for SCP), enabling stable CCM operation at >50% duty cycle. Its proprietary 900V monolithic process integrates the power FET and thermal shutdown circuitry on a single die.

It uses an external resistor on FSET to set oscillator frequency (90–300kHz typ), combined with ±4% frequency jittering to reduce EMI peak energy. Protection logic includes time-based overload detection (82ms delay), auto-recovery SCP, VCC OVP (26.0V typ), and PRO pin for external input OVP coordination.

Key Specifications

Pinout & Package

HF900GS-P is housed in a SOIC14-11 package with exposed pad for thermal enhancement. Pin 13 is NC; pins 1,2,7,8 are GND; pin 14 is DRAIN; pin 9 is SOURCE; pins 3–6 map to FSET, VCC, FB, and PRO respectively.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP6004GQ-Z and UCC28632DR, HF900GS-P uniquely supports 420VAC operation with monolithic 900V integration and on-die OTP-making it the only choice for smart meters and industrial equipment deployed on unstable high-voltage grids.

Availability

HF900GS-P is available at Aetrix Electronics and suitable for smart metering, industrial motor control PSUs, and large-appliance auxiliary power supplies requiring stable component supply under extended temperature and high-voltage stress conditions.

Supply support for HF900GS-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 over two decades of expertise in DC/DC conversion and power management.

The HF900 product line targets high-reliability offline AC/DC conversion in grid-connected infrastructure, emphasizing integrated 900V switching, EMI reduction, and autonomous protection for harsh environments.

FAQ

What is the maximum recommended continuous output power for HF900GS-P in SOIC14-11 package?

The SOIC14-11 package has a θJA of 70°C/W and max junction temperature of 150°C. At 25°C ambient, max continuous power dissipation is 1.45W. Accounting for conduction and switching losses, typical design limit is 12W output power with adequate PCB copper area and airflow - verified in MPS evaluation board testing at 230VAC input.

Can HF900GS-P operate without an auxiliary winding for VCC supply?

Yes - the internal high-voltage current source draws from DRAIN to bootstrap VCC during start-up. Once VCC reaches 13.0V, the IC switches and transitions to auxiliary winding supply. If auxiliary winding fails, the IC reverts to DRAIN sourcing and enters auto-recovery mode, ensuring robustness in transformer-coupled designs.

How does the PRO pin interface with external over-voltage protection circuits?

PRO accepts a divided input voltage (e.g., from resistive divider across bulk capacitor). When PRO voltage exceeds 3.1V, the IC shuts down and enters auto-recovery. A 1nF ceramic capacitor must be placed directly between PRO and GND to suppress switching noise - confirmed in MPS AN-107 application note.

Is the FSET resistor value affected by temperature drift in high-ambient applications?

Yes - FSET sets frequency via current into an internal oscillator. Resistor temperature coefficient impacts accuracy: a 100kΩ 1% metal-film resistor (±100ppm/°C) causes ~0.8% frequency shift from –40°C to +125°C. For precision timing, use low-TCR resistors or calibrate at operating temperature.

Does HF900GS-P support synchronous rectification on the secondary side?

No - HF900GS-P is a primary-side controller only. It provides no gate drive signals for synchronous rectifiers. Secondary-side regulation relies on optocoupler feedback to FB; SR controllers like MP6908 must be used externally if synchronous rectification is required.

What is the minimum FB voltage required to prevent unintended burst-mode entry during normal regulation?

Normal regulation requires FB to remain above 0.58V (VBURH min) to stay out of burst mode. The FB voltage is typically held at ~2.5V via optocoupler feedback loop; entering burst mode only occurs when load drops sufficiently to pull FB below 0.5V (VBURL max), confirmed in Figure 4 waveform analysis.

How is leading-edge blanking (LEB) configured - is it adjustable or fixed?

LEB is fully internal and fixed: 350ns for primary current sensing (TLEB1) and 300ns for short-circuit protection (TLEB2). No external components or configuration pins affect LEB timing - both values are characterized across temperature and process corners per datasheet Table 1.