BS170 MOSFET — Specifications & Equivalents
About the BS170
The BS170 is an N-channel MOSFET with a drain–source voltage (VDS) rating of 60 V, a continuous drain current (ID) of 0.5 A and an on-resistance (RDS(on)) of 5 Ω. It can dissipate up to 0.83 W and is rated to a junction temperature of 150 °C. It is supplied in the TO92 package.
At a glance
- Type: N-channel MOSFET
- Max drain–source voltage (VDS): 60 V
- Max continuous drain current (ID): 0.5 A
- On-resistance (RDS(on)): 5 Ω
- Gate threshold (VGS(th)): 3 V
- Power dissipation (PD): 0.83 W
- Max junction temperature (TJ): 150 °C
- Package: TO92
Typical applications
With its 60 V drain–source rating the BS170 sits in the mid-range class of switching MOSFETs, typically found in 24 V and 48 V industrial and battery systems, motor drives and H-bridges and load and hot-swap switching.
At 0.5 A it is aimed at small-signal and light-load switching rather than power conversion.
On-resistance of 5 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
With a gate threshold (VGS(th)) of 3 V this is not a logic-level device: driving the gate directly from a 3.3 V or 5 V microcontroller pin will leave it only partly on and cause it to overheat. Use a gate driver or level shifter, typically taking VGS to 10 V.
Keep gate–source voltage within the ±20 V maximum; exceeding it punctures the gate oxide and destroys the device permanently.
Choosing a replacement for the BS170
A drop-in substitute for the BS170 must be the same N-channel type and offer a drain–source rating of at least 60 V, a continuous drain current rating of at least 0.5 A, an on-resistance no higher than 5 Ω if efficiency and heat matter and a comparable gate threshold, so your existing gate drive still fully enhances the device.
Mechanically, check the replacement against the TO92 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 BS170?
The BS170 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 60 V drain-source and 0.5 A continuous drain current.
What is the maximum voltage of the BS170?
The BS170 has a maximum drain-source voltage (Vds) of 60 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.
How much current can the BS170 handle?
It is rated for 0.5 A of continuous drain current, with power dissipation limited to 0.83 W. Real-world capability depends on your heatsinking and ambient temperature.
What is the on-resistance of the BS170?
On-resistance (Rds(on)) is 5 Ω. Multiply by the square of your load current to estimate conduction loss.
Is the BS170 logic-level compatible?
No. The gate threshold is 3 V, so a 3.3 V or 5 V logic output cannot fully turn it on. Use a gate driver and take Vgs to around 10 V.
What package does the BS170 come in?
It is listed in TO92. Verify the pinout of the specific variant, as one outline can carry different pin assignments.
What can I use to replace the BS170?
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) | 60 V |
| Gate-Source Voltage (Vgs) | 20 V |
| Gate Threshold Voltage (Vgsth) | 3 V |
| Drain Current (Id) | 0.5 A |
| Drain-Source On-Resistance (Rds) | 5 |
| Junction Temperature (Tj) | 150 °C |
| Package | TO92 |
| Power Dissipation (Pd) | 0.83 W |
Equivalent & Replacement Parts
No verified equivalents are listed for BS170 yet.