onsemi FDMS86350 PowerTrench MOSFET: Datasheet, Application Circuit, and Pinout Explanation
The onsemi FDMS86350 represents a high-performance N-channel MOSFET engineered using the advanced PowerTrench® process technology. This component is specifically designed for demanding switching applications, offering an exceptional balance of low on-resistance and high switching speed, making it a prime choice for power management solutions in compact, high-efficiency designs.
Datasheet Overview and Key Specifications
The datasheet for the FDMS86350 provides a comprehensive look at its electrical characteristics and absolute maximum ratings. Understanding these parameters is critical for ensuring reliable operation within a circuit.
Key specifications include:
Drain-Source Voltage (VDS): 60 V. This defines the maximum voltage that can be applied between the drain and source terminals.
Continuous Drain Current (ID): 16 A at a case temperature of 25°C. This is the maximum continuous current the device can handle.
On-Resistance (RDS(on)): A remarkably low 3.0 mΩ (max) at VGS = 10 V. This is a crucial figure of merit (FOM) as it directly determines the conduction losses and efficiency of the switch; lower RDS(on) means less power is wasted as heat.
Gate Threshold Voltage (VGS(th)): Typically 2.1 V, which is the minimum voltage required to turn the device on.
Package: The MOSFET is housed in an SO-8FL package. This package offers a low profile and a small footprint, which is essential for modern, space-constrained PCB designs, while also providing improved thermal performance over standard SOIC packages.
Application Circuit: A Typical Synchronous Buck Converter
A primary application for the FDMS86350 is as the low-side synchronous rectifier in a DC-DC buck converter circuit. In this setup, a control IC drives a high-side switch (another MOSFET) and the FDMS86350 alternately.
1. When the high-side switch turns on, the input voltage is applied to the inductor, storing energy, and the FDMS86350 is off.
2. When the high-side switch turns off, the control IC turns on the FDMS86350, providing a path for the inductor current to continue flowing to the load. Its ultra-low RDS(on) is critical here to minimize voltage drop and power loss during this freewheeling phase, thereby maximizing the overall efficiency of the power supply.
This device is also perfectly suited for other applications requiring high-speed switching and high current handling, such as motor control circuits and power OR-ing functions.
Pinout Explanation
The FDMS86350 utilizes a standard 8-pin SOIC package, but its pinout is optimized for power applications. It features four pins dedicated to the drain and four to the source to minimize parasitic resistance and inductance.
Pins 1, 2, 7, 8 (Drain): These pins are all internally connected to the Drain terminal of the MOSFET. Connecting all four to the PCB's power plane is essential to handle high current and improve thermal dissipation.
Pins 3, 4, 5, 6 (Source): These pins are all internally connected to the Source terminal of the MOSFET. They must be connected to the ground plane or the appropriate circuit node.
Gate (Typically Pin 5 or as per marking): While the source pins are for current, the gate control signal is connected to a specific pad. It is vital to consult the package drawing in the datasheet to correctly identify the gate pin location for driving the device.
ICGOOODFIND: The onsemi FDMS86350 PowerTrench MOSFET stands out as an exceptional component for high-efficiency power conversion. Its defining strengths are an ultra-low RDS(on) of just 3.0 mΩ and a compact SO-8FL package, making it an ideal solution for space-constrained, high-current applications like synchronous buck converters and motor drives, where minimizing power loss and thermal management are paramount.
Keywords: PowerTrench MOSFET, Low RDS(on), Synchronous Rectification, Buck Converter, SO-8FL Package.
