High Current High Side Only Gate Driver# Technical Documentation: FAN7371 High-Voltage Half-Bridge Gate Driver IC
Manufacturer : FAIRCHILD SEMICONDUCTOR (now part of ON Semiconductor)
## 1. Application Scenarios
### 1.1 Typical Use Cases
The FAN7371 is a monolithic high-voltage, high-speed power MOSFET and IGBT gate driver designed for applications requiring high-side and low-side switching. Its primary function is to provide robust gate drive signals while handling significant voltage differentials between control logic and power switches.
Primary Operational Modes:
- Half-Bridge/Full-Bridge Configurations : Driving two power switches (typically MOSFETs or IGBTs) in complementary or independent switching patterns.
- High-Side Switching : Specifically capable of driving a switch where the source/emitter voltage floats at high potential relative to system ground.
- Bootstrap Operation : Utilizes an external bootstrap capacitor and diode to generate the floating supply voltage for the high-side driver, eliminating the need for an isolated power supply.
### 1.2 Industry Applications
The FAN7371 is deployed across multiple power electronics sectors due to its high-voltage capability (up to 600V) and robust design.
Motor Drive Systems:
- Industrial Motor Controls : AC induction, BLDC, and stepper motor drives in conveyor systems, pumps, and compressors.
- Consumer Appliances : Inverter-driven compressors in air conditioners, refrigerators, and washing machines.
- Electric Mobility : E-bike motor controllers, electric power steering (EPS) systems.
Power Conversion:
- Switched-Mode Power Supplies (SMPS) : Particularly in half-bridge and full-bridge topologies for server PSUs, telecom rectifiers, and industrial power supplies.
- Uninterruptible Power Supplies (UPS) : Inverter stages converting DC battery voltage to AC output.
- Solar Inverters : DC-AC conversion stages in micro and string inverters.
Lighting:
- High-Intensity Discharge (HID) Ballasts : Electronic ballasts for automotive and industrial lighting.
- LED Drivers : High-power LED drivers using buck, boost, or buck-boost topologies.
### 1.3 Practical Advantages and Limitations
Advantages:
- High Voltage Isolation : Can withstand up to 600V between high-side and low-side, enabling direct use in many offline and high-voltage DC applications.
- Integrated Bootstrap Functionality : Simplifies design by eliminating the need for a separate isolated DC-DC converter for the high-side supply.
- Robustness : Features under-voltage lockout (UVLO) for both channels, preventing power device operation at insufficient gate voltage, which reduces the risk of shoot-through and thermal runaway.
- Fast Switching : Typical propagation delays of 60ns (max) enable high-frequency switching (up to several hundred kHz), improving power density and reducing magnetic component size.
- Cross-Conduction Prevention : Built-in dead-time control (though external adjustment is often recommended for optimization) prevents simultaneous conduction of high-side and low-side switches.
Limitations:
- Bootstrap Limitations : In applications with extremely long high-side on-times or very low duty cycles, the bootstrap capacitor may discharge, causing high-side UVLO fault. This necessitates careful capacitor selection or alternative bias supply methods.
- dv/dt Immunity : While robust, extremely high voltage slew rates (common in hard-switching topologies at high voltage/current) can induce parasitic turn-on via Miller capacitance. This often requires external gate resistors or Miller clamp circuits.
- Peak Current Capability : The typical 2.5A source/3.5A sink current may be insufficient for very large MOSFET/IGBT modules with extremely high gate charge (Qg). Parallel drivers or external buffer stages may be required.
- Thermal Management : In
