onsemi FDC3601N Dual N-Channel PowerTrench MOSFET: Datasheet, Application Circuit, and Pinout Explanation

The onsemi FDC3601N is a highly integrated dual N-Channel MOSFET utilizing advanced PowerTrench® technology, designed to deliver superior efficiency and power density in a compact package. This device is engineered for demanding power management applications, offering a low on-state resistance (RDS(on)) and high switching performance. Its common-centroid configuration within the DFN5 2x2 package enhances thermal performance and simplifies PCB layout by improving symmetry.

Datasheet Overview and Key Specifications

A thorough review of the FDC3601N datasheet reveals its critical electrical characteristics. Key parameters include a drain-source voltage (VDS) of 30V, making it suitable for low-voltage applications such as DC-DC conversion in computing and consumer electronics. Each MOSFET features a continuous drain current (ID) rating of 6.5A, with a very low typical RDS(on) of 13.5 mΩ at VGS = 10V. This low resistance is pivotal for minimizing conduction losses and improving overall system efficiency. The device is also characterized by its low gate charge (Qg), which reduces switching losses and allows for higher frequency operation.

Pinout Explanation

The FDC3601N is housed in a space-saving DFN5 2x2 package with a thermally enhanced exposed pad. The pinout is as follows:

Pin 1 (Source 1): The source terminal for the first MOSFET.

Pin 2 (Gate 1): The gate control pin for the first MOSFET.

Pin 3 (Drain 1 & Drain 2): This is a common drain connection for both MOSFETs internally. This configuration is ideal for half-bridge and synchronous rectifier topologies.

Pin 4 (Gate 2): The gate control pin for the second MOSFET.

Pin 5 (Source 2): The source terminal for the second MOSFET.

Exposed Pad (Source 1 & Source 2): The pad on the bottom of the package is internally connected to both source pins (Source 1 and Source 2). This pad must be soldered to the PCB ground plane to provide both electrical connection and a critical path for heat dissipation.

Application Circuit: Synchronous Buck Converter

A primary application for the FDC3601N is in a synchronous buck converter circuit, a core component of voltage regulator modules (VRMs) and point-of-load (POL) converters.

In this circuit:

The high-side MOSFET (control FET) is switched actively to control the energy transfer from the input to the output.

The low-side MOSFET (synchronous FET) acts as a rectifier, conducting during the freewheeling period.

The FDC3601N is perfectly suited for this role because its common-drain, separate-source configuration allows one MOSFET to be used as the high-side switch and the other as the low-side switch. The integrated design minimizes parasitic inductance in the critical switching loop, leading to reduced voltage overshoot and lower electromagnetic interference (EMI). The low RDS(on) and Qg work in tandem to maximize efficiency across the load range.

ICGOODFIND Summary

The onsemi FDC3601N stands out as an excellent solution for compact, high-efficiency power conversion. Its dual N-Channel design in a common-drain configuration simplifies the implementation of synchronous rectification circuits. The combination of low RDS(on) and a thermally efficient DFN package ensures robust performance in a minimal footprint, making it a top choice for modern power supply designs in portable and computing applications.

Keywords: PowerTrench MOSFET, Synchronous Buck Converter, Low RDS(on), DFN Package, Dual N-Channel