Onsemi FDG6320C Dual N-Channel Logic Level MOSFET: Features and Application Circuit Design
The Onsemi FDG6320C is a highly integrated dual N-channel logic-level MOSFET that provides a compact and efficient solution for power management and switching applications. Encased in a space-saving SC-70-6 package, this component is engineered to deliver high performance in low-voltage, high-speed circuits. Its ability to be driven directly from logic-level signals (as low as 1.8 V) makes it an indispensable part of modern portable electronics, computing peripherals, and embedded systems.
Key Features of the FDG6320C
The standout characteristics of the FDG6320C are its low on-resistance (RDS(ON)) and its logic-level gate drive capability. With a typical RDS(ON) of just 90 mΩ at VGS = 4.5 V, the device minimizes conduction losses, leading to higher efficiency and reduced heat generation. This is critical for battery-operated devices where every milliwatt of power saved extends operational life.
Furthermore, the dual independent MOSFETs in a single package allow designers to halve the board space required for two discrete transistors, simplifying layout and reducing the overall bill of materials (BOM). The device also features a low gate threshold voltage (VGS(th)), typically around 1 V, ensuring robust turn-on with microcontrollers (MCUs) and digital signal processors (DSPs) without the need for additional gate-drive circuitry.
Application Circuit Design: A DC Motor Driver
A common and practical application for the FDG6320C is in the design of a compact H-Bridge circuit for bidirectional control of a small DC motor. This circuit allows the motor to run forwards and backwards, which is essential in applications like camera lens control, robotic movements, or automated valves.
In a simplified H-Bridge design, two FDG6320C packages (four total N-channel MOSFETs) can be used. The two MOSFETs within a single package can be used for the high-side or low-side switches of one half-bridge. However, as the FDG6320C is an N-channel device, driving the high-side switches requires a bootstrap circuit or a charge pump to generate a gate voltage higher than the motor's supply voltage (Vmotor).
Circuit Design Considerations:
1. Gate Driving: While the MOSFETs are logic-level, ensure the MCU's GPIO pins can supply sufficient peak current to charge and discharge the gate capacitance quickly. A small series gate resistor (e.g., 10 - 100 Ω) is recommended to dampen ringing and prevent oscillations.
2. Freewheeling Diodes: The internal body diodes of the MOSFETs provide a path for inductive kickback current when the motor is switched off. For better efficiency and thermal performance, especially with PWM speed control, external Schottky diodes can be added in parallel to handle the reverse current with a lower forward voltage drop.
3. Decoupling: Place a 100 nF ceramic capacitor very close to the Vmotor pin of the MOSFET package to provide a local high-frequency charge source, minimizing voltage spikes on the power supply rail.
4. Protection: Incorporate fuse protection on the main Vmotor line and consider using sense resistors with an operational amplifier for over-current detection and shutdown.
This design showcases the FDG6320C's strength in creating compact, efficient, and reliable motor control systems without sacrificing precious PCB real estate.
The Onsemi FDG6320C stands out as an exemplary component for space-constrained, low-power switching designs. Its integration of two high-performance MOSFETs, combined with exceptional logic-level compatibility and low RDS(ON), provides engineers with a versatile building block for a wide array of applications, from load switching and motor driving to power management in portable devices.
Keywords:
Logic-Level MOSFET
Low RDS(ON)
Dual N-Channel
SC-70-6 Package
Application Circuit Design
