onsemi FQPF9N90CT: A Comprehensive Guide to the 900V N-Channel MOSFET
The onsemi FQPF9N90CT stands as a robust 900V N-Channel MOSFET engineered for high-voltage, high-speed switching applications. Utilizing advanced planar stripe DMOS technology, this Power MOSFET is housed in a TO-220F full-pack (isolated) package, offering a compelling combination of high voltage capability, low gate charge, and low on-resistance. This article delves into its datasheet specifications, a typical application circuit, and its pinout configuration.
Datasheet Overview and Key Specifications
The FQPF9N90CT is designed for durability and efficiency. Its key electrical characteristics make it suitable for demanding environments.
Drain-to-Source Voltage (VDSS): 900V. This high voltage rating is ideal for off-line power supplies and other mains-connected circuits.
Continuous Drain Current (ID): 8.5A at a case temperature of 25°C. This provides substantial current handling capability.
On-Resistance (RDS(on)): A maximum of 1.3Ω at 4.5A, 25°C. Low on-resistance is crucial for minimizing conduction losses and improving overall system efficiency.
Gate Charge (Qg): 24nC (typical). Low gate charge allows for faster switching speeds and reduces the drive power required from the controller IC.
Avalanche Energy Rated: This feature ensures ruggedness and reliability against inductive switching spikes and unexpected voltage transients.
Pinout Configuration
The device comes in a TO-220F full-pack (fully isolated) package. This means the metal tab is electrically isolated from the die, allowing for easier mounting to a heatsink without an insulating kit. The pinout is standard for a TO-220F package:
1. Pin 1 (Gate): The control pin. A voltage applied between the Gate and Source terminals controls the flow of current between the Drain and Source.
2. Pin 2 (Drain): The output terminal connected to the high-voltage load.
3. Pin 3 (Source): The common return terminal, typically connected to ground.
Typical Application Circuit
A primary application for the FQPF9N90CT is in switch-mode power supplies (SMPS), such as power factor correction (PFC) stages and flyback converters. The following describes a simplified flyback converter circuit:
1. Controller IC: A PWM (Pulse Width Modulation) controller generates the switching signal.
2. Gate Drive: The output of the controller is fed to the Gate pin of the MOSFET, often through a gate driver IC or a resistor to control switching speed.
3. Primary Side: The Drain pin is connected to the high-voltage DC bus (e.g., rectified mains voltage) through the primary winding of a transformer.
4. Switching Operation: As the MOSFET switches on and off, energy is stored in the transformer's core when on and released to the secondary (output) side when off.
5. Clamping/Protection: A snubber circuit (e.g., a resistor-capacitor-diode network) is often placed across the transformer primary or the MOSFET itself to suppress voltage spikes and protect the 900V-rated device from exceeding its maximum voltage rating.
ICGOOODFIND: The onsemi FQPF9N90CT is a high-performance MOSFET that offers a critical balance of very high voltage blocking capability and low switching losses. Its fully isolated package simplifies thermal management, making it an excellent choice for designers of industrial power systems, high-voltage switch-mode power supplies, and lighting ballasts where reliability under stress is paramount.
Keywords: 900V MOSFET, Switch-Mode Power Supply, Low Gate Charge, Avalanche Rated, TO-220F Package
