Monolithic Power Systems Inc. HF920GSE

Overview

HF920GSE from Monolithic Power Systems is a monolithic 900V flyback switching regulator IC integrating a high-voltage power MOSFET, current-mode controller, and comprehensive protection circuitry. It delivers fixed-frequency operation up to 150kHz, <30mW no-load standby consumption, and burst-mode control for smart meters, industrial controls, and large appliances operating on poor AC grids (85–420Vac).

For engineers reviewing the HF920GSE datasheet, HF920GSE pinout, HF920GSE application, or HF920GSE equivalent, this page provides verified technical context, SOIC8-7A package mapping, real-world EMI mitigation features (frequency jittering + doubling), and design-critical parameters including R_DS(ON) = 15Ω @ 25°C, V_(BR)DSS = 900V, and OTP threshold at 150°C.

Technical Context

The HF920GSE implements peak-current-mode control with internal slope compensation and leading-edge blanking (t_LEB1 = 385ns, t_LEB2 = 350ns) to ensure stable regulation under transient load steps and prevent false triggering during MOSFET turn-on spikes. Its programmable oscillator uses an external resistor on FSET to set f_S from 43–150kHz, with ±3.5% frequency jittering to reduce EMI peak energy.

Burst-mode operation activates when FB voltage falls below 0.4–0.6V, disabling switching pulses to achieve <30mW no-load consumption; recovery occurs at FB > 0.6–0.8V. Frequency-doubling mode engages when FB reaches 3.3–4.0V (OLP threshold), doubling f_S to maintain regulation despite up to 50% inductance drop from magnetic interference.

Key Specifications

Pinout & Package

HF920GSE is housed in an SOIC8-7A package with exposed GND pad for thermal dissipation (θ_JA = 96°C/W, θ_JC = 45°C/W). The "7A" suffix denotes a modified SOIC-8 footprint where Pin 5 is internally connected to GND (not NC), enabling enhanced thermal performance over standard SOIC-8.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP6004GQ-Z and UCC28881DR, HF920GSE uniquely supports 420Vac operation, integrates 900V/15Ω MOSFET for highest input ruggedness, and offers frequency doubling - making it the only option capable of sustaining regulation under severe magnetic interference in wide-input industrial applications.

Availability

HF920GSE is available at Aetrix Electronics and suitable for smart metering, industrial PLC power supplies, and large appliance control boards requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for HF920GSE 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, and global manufacturing partnerships.

The HF920GSE belongs to MPS's high-voltage offline regulator product line, engineered specifically for reliable, low-standby-power AC/DC conversion in utility-grade and industrial environments where input voltage instability and EMI sensitivity are critical constraints.

FAQ

What is the maximum continuous input voltage the HF920GSE can withstand?

The HF920GSE integrates a 900V MOSFET with guaranteed V_(BR)DSS ≥ 900V, allowing direct connection to rectified AC inputs up to 420Vac (≈595VDC peak). Absolute maximum drain voltage is rated at 900V, and operation above 850V risks exceeding safe operating area limits even briefly.

How does the frequency doubling mode improve reliability in industrial settings?

Frequency doubling activates when FB voltage reaches the OLP threshold (3.3–4.0V), doubling the switching frequency to maintain regulation if transformer inductance drops up to 50% due to external magnetic fields. This prevents output collapse during solenoid actuation or motor startup near the power supply.

Can the HF920GSE operate without an auxiliary winding?

No - the HF920GSE requires an auxiliary winding to power VCC after startup. The internal HV current source on the D pin only supplies initial charge; once VCC reaches VCCH (12–14V), the IC switches to auxiliary winding supply. Without it, the device will repeatedly cycle in UVLO.

What is the purpose of the PRO pin, and how should it be implemented?

The PRO pin provides external fault detection with 3.1V threshold and 0.2V hysteresis. It is commonly used for input overvoltage protection by connecting a resistor divider from rectified AC to PRO. When pulled above 3.32V, it initiates auto-restart shutdown; recovery occurs when PRO falls below 2.92V.

Does the HF920GSE require external slope compensation?

No - the HF920GSE includes internal slope compensation optimized for its current-mode architecture. External slope compensation is unnecessary and would interfere with the built-in ramp (21mV/μs typical), which ensures stability across all operating conditions including CCM and DCM transitions.

How is thermal performance affected by the SOIC8-7A package's GND pad layout?

The SOIC8-7A package requires a minimum 3cm² copper area connected to Pins 5–8 (GND) for thermal dissipation. With this layout, θ_JA is 96°C/W; reducing copper area increases junction temperature rise linearly - e.g., halving copper area raises θ_JA to ~140°C/W, risking OTP activation at lower loads.

What is the minimum recommended input bulk capacitor value for 230Vac operation?

For 230Vac ±15% input, the recommended minimum input bulk capacitance is 1μF/W (half the universal 2μF/W value). For a 9.5W output (SOIC14-11 max), use ≥10μF/400V electrolytic. Lower values risk excessive V_DC(min) droop, causing premature UVLO and reduced hold-up time.