Landing Correction IC# Technical Documentation: FAN7071 High-Voltage Half-Bridge Gate Driver IC
Manufacturer : FAIRCHILD (now part of ON Semiconductor)
Document Revision : 1.0
Date : October 26, 2023
---
## 1. Application Scenarios
The FAN7071 is a monolithic high-voltage, high-speed power MOSFET and IGBT driver designed for applications requiring high efficiency, compact size, and robust performance in half-bridge or synchronous buck converter topologies.
### 1.1 Typical Use Cases
Motor Drive Systems
- Brushless DC (BLDC) Motor Controllers : The FAN7071 provides the necessary high-side and low-side gate driving capability for 3-phase inverter bridges, commonly used in automotive cooling fans, industrial pumps, and drone propulsion systems.
- Stepper Motor Drivers : In microstepping applications requiring precise current control, the driver ensures clean switching transitions for smooth motor operation.
Switched-Mode Power Supplies (SMPS)
- Synchronous Buck Converters : For point-of-load (POL) regulators in computing and telecom equipment, where efficiency at high switching frequencies (up to 500 kHz) is critical.
- Half-Bridge and Full-Bridge Topologies : Used in AC-DC power supplies (e.g., server PSUs) and DC-DC converters requiring high-voltage operation.
Lighting Systems
- LED Drivers : In high-power LED arrays for architectural and industrial lighting, where constant current regulation is achieved through half-bridge LLC resonant converters.
Renewable Energy
- Solar Microinverters : Converts DC from photovoltaic panels to AC, with the FAN7071 driving the high-voltage switches in the inverter stage.
### 1.2 Industry Applications
- Automotive : Engine control units (ECUs), electric power steering (EPS), and battery management systems (BMS) for 12V/24V systems.
- Consumer Electronics : Gaming consoles, high-end audio amplifiers, and LCD TV power boards.
- Industrial Automation : Programmable logic controller (PLC) power modules, robotic arm drives, and conveyor motor controls.
- Telecommunications : Base station power amplifiers and rectifier modules.
### 1.3 Practical Advantages and Limitations
Advantages:
- Integrated Bootstrap Functionality : Simplifies design by eliminating the need for an external high-side supply.
- High Noise Immunity : Typical 50 V/ns common-mode rejection (CMR) ensures stable operation in electrically noisy environments.
- Wide Voltage Range : Operates with a supply voltage (Vcc) from 10V to 20V, compatible with standard 12V rails.
- Fast Switching Speeds : Typical rise/fall times of 30 ns/20 ns minimize switching losses in high-frequency applications.
Limitations:
- Peak Current Capability : Maximum source/sink current of 0.5A/1.0A may be insufficient for driving very large MOSFETs or parallel devices without additional buffering.
- Temperature Constraints : Junction temperature range of -40°C to +125°C may require thermal management in high-ambient environments.
- Voltage Thresholds : Fixed undervoltage lockout (UVLO) thresholds may not be adjustable for custom startup sequences.
---
## 2. Design Considerations
### 2.1 Common Design Pitfalls and Solutions
Pitfall 1: Bootstrap Capacitor Selection
- Issue : Inadequate capacitance leads to high-side gate drive undervoltage during extended high-side switch conduction.
- Solution : Calculate bootstrap capacitance using:
\[
C_{boot} \geq \frac{2 \times Q_g}{V_{cc} - V_f - V_{LS}}
\]
Where \(Q_g\) is the total gate charge, \(V_f
