Half Bridge Gate Driver# Technical Documentation: FAN73832 High-Voltage Half-Bridge Gate Driver IC
Manufacturer : FAIRCHILD SEMICONDUCTOR (now part of ON Semiconductor)
## 1. Application Scenarios
### Typical Use Cases
The FAN73832 is a monolithic high-voltage, high-speed gate driver IC designed to drive both high-side and low-side N-channel power MOSFETs or IGBTs in a half-bridge configuration. Its primary function is to provide the necessary voltage translation, isolation, and drive current to efficiently switch high-power transistors.
* Motor Drive Circuits : It is extensively used in variable-frequency drives (VFDs) for 3-phase AC motors, brushless DC (BLDC) motor controllers, and stepper motor drivers. Its ability to handle bootstrap operation makes it ideal for driving the high-side switch in these applications.
* Switch-Mode Power Supplies (SMPS) : Employed in high-power topologies such as half-bridge, full-bridge, and active-clamp forward converters, commonly found in server power supplies, telecom rectifiers, and industrial power units.
* DC-AC Inverters : A core component in uninterruptible power supplies (UPS), solar microinverters, and frequency converters, where it drives the H-bridge or 3-phase bridge legs to generate AC output from a DC source.
* Electronic Ballasts and Induction Heating : Used to drive resonant half-bridge circuits in high-frequency lighting and heating applications.
### Industry Applications
* Industrial Automation : Drives for conveyor systems, pumps, fans, and robotic arms.
* Consumer Appliances : Inverter technology in air conditioners, refrigerators, and washing machines for improved efficiency.
* Renewable Energy : Power conversion stages in solar inverters and small wind turbine systems.
* Automotive : Potential use in auxiliary power modules and high-voltage subsystems in electric and hybrid vehicles (subject to appropriate grade selection).
### Practical Advantages and Limitations
Advantages:
* Integrated High-Voltage Technology : Contains a floating high-side driver capable of operating with a bootstrap supply, simplifying design by eliminating the need for an isolated DC-DC converter.
* Robustness : Features under-voltage lockout (UVLO) for both VCC and VB-VS (high-side supply), preventing malfunction at insufficient voltages. It also includes a shutdown pin and interlocking logic to prevent shoot-through currents.
* High Noise Immunity : Offers excellent dV/dt immunity (typically ±50 V/ns) due to its level-shift circuitry, which is critical in noisy switching environments.
* Compact Solution : Replaces multiple discrete components (level-shifters, drivers, diodes), reducing PCB area and improving reliability.
Limitations:
* Bootstrap Limitation : The high-side drive relies on a bootstrap capacitor. This limits the maximum duty cycle and requires careful calculation of the capacitor value for continuous operation. It is not suitable for applications requiring a 100% duty cycle on the high-side switch.
* Propagation Delay Mismatch : Although minimized, a slight mismatch (typically tens of nanoseconds) exists between the high-side and low-side propagation delays. This must be accounted for in high-frequency designs to avoid shoot-through.
* Peak Current Capability : While capable of sourcing/sinking significant peak current (typ. 2.5A/3.5A), driving very large MOSFETs with extremely high gate charge (Qg) may require an external booster stage.
## 2. Design Considerations
### Common Design Pitfalls and Solutions
1. Pitfall: Bootstrap Circuit Failure
* Cause : Undersized bootstrap capacitor, causing it to discharge below the UVLO threshold during extended high-side ON periods. Excessive voltage drop across the bootstrap diode.
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