Monolithic Power Systems Inc. HF900GPR

Overview

HF900GPR from Monolithic Power Systems is a 900V offline flyback switching regulator with integrated high-voltage MOSFET, peak-current-mode control, programmable switching frequency up to 300kHz, and burst-mode operation for <100mW standby power. It targets AC/DC power supplies in smart meters, industrial controls, and large appliances operating on unstable AC grids.

For engineers reviewing the HF900GPR datasheet, HF900GPR pinout, HF900GPR application, or HF900GPR equivalent, key selection criteria include its 900V drain rating, internal OTP co-integrated with the power FET, VCC UVLO hysteresis (3.6V typ), FB-triggered burst mode (0.5V entry / 0.7V exit), and FSET-programmable jittering frequency for EMI reduction.

Technical Context

The HF900GPR 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 operation at duty cycles >50% in CCM. Its proprietary 900V monolithic process integrates the power switch and thermal shutdown (150°C trip, 30°C hysteresis) on a single die.

Startup is managed by an internal high-voltage current source drawn from DRAIN, transitioning to auxiliary-winding-derived VCC once VCCH (13.0V typ) is reached; VCC UVLO hysteresis ensures robust restart after fault recovery. Protection includes time-based OLP (82ms delay at 100kHz), SCP (1.42V threshold), VCC OVP (26.0V), and PRO-pin configurable input OVP.

Key Specifications

Pinout & Package

HF900GPR is packaged in PDIP8-7EP (plastic dual in-line, 7 exposed pads for thermal enhancement), offering 1.47W continuous power dissipation at TA = +25°C and θJA = 68°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP101G and UCC28881DR, HF900GPR delivers superior grid resilience (900V), lower system-level EMI (jittering + programmable fS), and lowest standby (burst mode + integrated OTP), making it optimal for safety-critical, high-reliability AC/DC designs.

Availability

HF900GPR is available at Aetrix Electronics and suitable for smart metering, industrial automation, and appliance power supply designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for HF900GPR 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 HF900 belongs to MPS's high-voltage offline regulator product line, engineered specifically for reliable, low-component-count AC/DC conversion in harsh-grid environments and safety-critical infrastructure.

FAQ

What is the maximum recommended operating junction temperature for HF900GPR?

The absolute maximum junction temperature is 150°C, at which point the integrated over-temperature protection activates and disables the MOSFET driver. Recovery occurs at 120°C due to 30°C hysteresis. Continuous operation above 125°C requires thermal derating per the θJA = 68°C/W specification and PCB copper area optimization.

Can HF900GPR operate without an auxiliary winding for VCC supply?

No. While the internal high-voltage current source powers the IC during startup from DRAIN, sustained operation requires VCC to be supplied by an auxiliary winding. The IC stops switching when VCC falls below VCCL (9.4V typ), and the internal current source resumes only during fault recovery-not during normal operation.

How does the PRO pin function in over-voltage protection schemes?

The PRO pin triggers immediate shutdown when voltage exceeds 3.1V (typ). It is commonly used with a resistor divider from the rectified input to detect over-voltage events. A 1nF ceramic capacitor must be placed directly between PRO and GND to suppress switching noise that could cause false triggering.

What is the minimum FSET resistor value to achieve 300kHz operation?

Using the formula fS = (9×10⁹)/(RFSET + 112.5×10³), a 300kHz target requires RFSET ≈ 21.5kΩ. A standard 22kΩ ±1% resistor yields ~295kHz (within datasheet tolerance), confirming feasibility. Lower values risk exceeding the 300kHz upper limit and violating timing margins.

Does HF900GPR support discontinuous conduction mode (DCM) operation?

Yes. The device supports both CCM and DCM. At light loads, burst mode dominates; at heavier loads, operation transitions to CCM when duty cycle and inductor design permit. Slope compensation is active in both modes to ensure subharmonic oscillation immunity above 50% duty cycle.

Is the NC pin (Pin 13 in SOIC14-11) electrically isolated or internally floating?

Pin 13 is a true no-connect terminal-internally unconnected and electrically isolated from all circuitry. It must remain unconnected on PCB; routing traces or vias to this pin may introduce parasitic coupling or mechanical stress risks.

How is short-circuit protection (SCP) implemented and what is its response time?

SCP triggers when the SOURCE pin voltage exceeds 1.42V (typ), indicating excessive primary current. Leading-edge blanking (300ns) prevents false trips from switching spikes. Once triggered, the IC enters auto-recovery mode within one switching cycle and resumes operation after fault removal.