BFT46 JFET — Specifications & Equivalents
About the BFT46
The BFT46 is an N-channel JFET with a drain–source voltage (VDS) rating of 25 V, a continuous drain current (ID) of 0.01 A and an on-resistance (RDS(on)) of 300 Ω. It can dissipate up to 0.25 W and is rated to a junction temperature of 150 °C. It is supplied in the SOT23 package.
At a glance
- Type: N-channel JFET
- Max drain–source voltage (VDS): 25 V
- Max continuous drain current (ID): 0.01 A
- On-resistance (RDS(on)): 300 Ω
- Power dissipation (PD): 0.25 W
- Max junction temperature (TJ): 150 °C
- Package: SOT23
Typical applications
With its 25 V drain–source rating the BFT46 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 0.01 A it is aimed at small-signal and light-load switching rather than power conversion.
On-resistance of 300 Ω is relatively high, so this part is better suited to low duty-cycle or low-current switching than to continuous high-current conduction.
Choosing a replacement for the BFT46
A drop-in substitute for the BFT46 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 0.01 A and an on-resistance no higher than 300 Ω if efficiency and heat matter.
Mechanically, check the replacement against the SOT23 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 BFT46?
The BFT46 is an N-channel junction field-effect transistor (JFET). It is rated for 25 V drain-source and 0.01 A continuous drain current.
What is the maximum voltage of the BFT46?
The BFT46 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 BFT46 handle?
It is rated for 0.01 A of continuous drain current, with power dissipation limited to 0.25 W. Real-world capability depends on your heatsinking and ambient temperature.
What is the on-resistance of the BFT46?
On-resistance (Rds(on)) is 300 Ω. Multiply by the square of your load current to estimate conduction loss.
What package does the BFT46 come in?
It is listed in SOT23. Verify the pinout of the specific variant, as one outline can carry different pin assignments.
What can I use to replace the BFT46?
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 | JFET |
|---|---|
| Channel Type | N -Channel |
| Drain-Source Voltage (Vds) | 25 V |
| Drain Current (Id) | 0.01 A |
| Drain-Source On-Resistance (Rds) | 300 |
| Output Capacitance (Coss) | 1.5 pF |
| Junction Temperature (Tj) | 150 °C |
| Package | SOT23 |
| Power Dissipation (Pd) | 0.25 W |
Equivalent & Replacement Parts
No verified equivalents are listed for BFT46 yet.