3N203 MOSFET — Specifications & Equivalents
About the 3N203
The 3N203 is an N-channel MOSFET with a drain–source voltage (VDS) rating of 25 V, a continuous drain current (ID) of 0.05 A and an on-resistance (RDS(on)) of 100 Ω. It can dissipate up to 0.36 W and is rated to a junction temperature of 175 °C. It is supplied in the TO72 package.
At a glance
- Type: N-channel MOSFET
- Max drain–source voltage (VDS): 25 V
- Max continuous drain current (ID): 0.05 A
- On-resistance (RDS(on)): 100 Ω
- Power dissipation (PD): 0.36 W
- Max junction temperature (TJ): 175 °C
- Package: TO72
Typical applications
With its 25 V drain–source rating the 3N203 sits in the very-low-voltage class of switching MOSFETs, typically found in battery protection and power-path switching, point-of-load converters and logic-level load switching in portable devices.
At 0.05 A it is aimed at small-signal and light-load switching rather than power conversion.
On-resistance of 100 Ω is relatively high, so this part is better suited to low duty-cycle or low-current switching than to continuous high-current conduction.
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.
Switching behaviour is characterised by an output capacitance (Coss) of 1.7 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.
Choosing a replacement for the 3N203
A drop-in substitute for the 3N203 must be the same N-channel type and offer a drain–source rating of at least 25 V, a continuous drain current rating of at least 0.05 A and an on-resistance no higher than 100 Ω if efficiency and heat matter.
Mechanically, check the replacement against the TO72 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 3N203?
The 3N203 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 25 V drain-source and 0.05 A continuous drain current.
What is the maximum voltage of the 3N203?
The 3N203 has a maximum drain-source voltage (Vds) of 25 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.
How much current can the 3N203 handle?
It is rated for 0.05 A of continuous drain current, with power dissipation limited to 0.36 W. Real-world capability depends on your heatsinking and ambient temperature.
What is the on-resistance of the 3N203?
On-resistance (Rds(on)) is 100 Ω. Multiply by the square of your load current to estimate conduction loss.
What package does the 3N203 come in?
It is listed in TO72. Verify the pinout of the specific variant, as one outline can carry different pin assignments.
What can I use to replace the 3N203?
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) | 25 V |
| Gate-Source Voltage (Vgs) | 30 V |
| Drain Current (Id) | 0.05 A |
| Drain-Source On-Resistance (Rds) | 100 |
| Output Capacitance (Coss) | 1.7 pF |
| Junction Temperature (Tj) | 175 °C |
| Package | TO72 |
| Power Dissipation (Pd) | 0.36 W |
Equivalent & Replacement Parts
No verified equivalents are listed for 3N203 yet.