FDB33N25 MOSFET — Specifications & Equivalents
Manufacturer: Commonly produced by Fairchild (now onsemi)
About the FDB33N25
The FDB33N25 is an N-channel MOSFET with a drain–source voltage (VDS) rating of 250 V, a continuous drain current (ID) of 33 A and an on-resistance (RDS(on)) of 0.094 Ω. It can dissipate up to 235 W and is rated to a junction temperature of 150 °C. It is available in TO263 and D2PAK packages, so confirm the pinout of the exact variant you order.
At a glance
- Type: N-channel MOSFET
- Max drain–source voltage (VDS): 250 V
- Max continuous drain current (ID): 33 A
- On-resistance (RDS(on)): 0.094 Ω
- Power dissipation (PD): 235 W
- Max junction temperature (TJ): 150 °C
- Package: TO263, D2PAK
- Manufacturer: Commonly produced by Fairchild (now onsemi)
Typical applications
With its 250 V drain–source rating the FDB33N25 sits in the medium-high-voltage class of switching MOSFETs, typically found in telecom and industrial DC rails, boost and flyback converters, LED and backlight drivers and power-factor-correction stages. Common where the bus sits well above 100 V but below rectified mains.
Gate drive and switching notes
Keep gate–source voltage within the ±30 V maximum; exceeding it punctures the gate oxide and destroys the device permanently.
Choosing a replacement for the FDB33N25
A drop-in substitute for the FDB33N25 must be the same N-channel type and offer a drain–source rating of at least 250 V, a continuous drain current rating of at least 33 A and an on-resistance no higher than 0.094 Ω if efficiency and heat matter.
Mechanically, check the replacement against the TO263 and D2PAK footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.
Where the application switches inductive loads or runs near the voltage limit, keep extra headroom rather than choosing a part that only just meets the original numbers.
Frequently asked questions
What is the FDB33N25?
The FDB33N25 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 250 V drain-source and 33 A continuous drain current.
What is the maximum voltage of the FDB33N25?
The FDB33N25 has a maximum drain-source voltage (Vds) of 250 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.
How much current can the FDB33N25 handle?
It is rated for 33 A of continuous drain current, with power dissipation limited to 235 W. Real-world capability depends on your heatsinking and ambient temperature.
What is the on-resistance of the FDB33N25?
On-resistance (Rds(on)) is 0.094 Ω. Multiply by the square of your load current to estimate conduction loss.
What package does the FDB33N25 come in?
It is listed in TO263 and D2PAK. Verify the pinout of the specific variant, as one outline can carry different pin assignments.
What can I use to replace the FDB33N25?
No verified equivalents are listed yet. Choose a part of the same polarity that meets or exceeds every rating above and shares a compatible package and pinout.
Key Specifications
| Type | MOSFET |
|---|---|
| Channel Type | N -Channel |
| Drain-Source Voltage (Vds) | 250 V |
| Gate-Source Voltage (Vgs) | 30 V |
| Drain Current (Id) | 33 A |
| Drain-Source On-Resistance (Rds) | 0.094 |
| Junction Temperature (Tj) | 150 °C |
| Package | TO263 D2PAK |
| Power Dissipation (Pd) | 235 W |
Equivalent & Replacement Parts
No verified equivalents are listed for FDB33N25 yet.