BSS123A MOSFET — Specifications & Equivalents
About the BSS123A
The BSS123A is an N-channel MOSFET with a drain–source voltage (VDS) rating of 100 V, a continuous drain current (ID) of 0.17 A and an on-resistance (RDS(on)) of 10 Ω. It can dissipate up to 0.36 W and is rated to a junction temperature of 150 °C. It is supplied in the SOT23 package.
At a glance
- Type: N-channel MOSFET
- Max drain–source voltage (VDS): 100 V
- Max continuous drain current (ID): 0.17 A
- On-resistance (RDS(on)): 10 Ω
- Power dissipation (PD): 0.36 W
- Max junction temperature (TJ): 150 °C
- Package: SOT23
Typical applications
With its 100 V drain–source rating the BSS123A sits in the medium-voltage class of switching MOSFETs, typically found in 48 V and 96 V distribution systems, solar and telecom power stages, DC motor drives and intermediate-bus DC-DC converters.
At 0.17 A it is aimed at small-signal and light-load switching rather than power conversion.
On-resistance of 10 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
Switching behaviour is characterised by an output capacitance (Coss) of 40 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.
Choosing a replacement for the BSS123A
A drop-in substitute for the BSS123A must be the same N-channel type and offer a drain–source rating of at least 100 V, a continuous drain current rating of at least 0.17 A and an on-resistance no higher than 10 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 BSS123A?
The BSS123A is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 100 V drain-source and 0.17 A continuous drain current.
What is the maximum voltage of the BSS123A?
The BSS123A has a maximum drain-source voltage (Vds) of 100 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.
How much current can the BSS123A handle?
It is rated for 0.17 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 BSS123A?
On-resistance (Rds(on)) is 10 Ω. Multiply by the square of your load current to estimate conduction loss.
What package does the BSS123A 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 BSS123A?
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) | 100 V |
| Drain Current (Id) | 0.17 A |
| Drain-Source On-Resistance (Rds) | 10 |
| Output Capacitance (Coss) | 40 pF |
| Junction Temperature (Tj) | 150 °C |
| Package | SOT23 |
| Power Dissipation (Pd) | 0.36 W |
Equivalent & Replacement Parts
No verified equivalents are listed for BSS123A yet.