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BSS123 Logic Level N-Channel Mosfet

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The BSS138 is an SMD Package (SOT23) Logic Level N-Channel MOSFET with drain current of 170mA and Drain Source Voltage of 100V. The MOSFET also has low threshold voltage of 1.7V typically.

Pin Configuration

Pin Number

Pin Name




Current flows out through Source



Controls the biasing of the MOSFET



Current flows in through Drain



·         Logic Level N-Channel MOSFET with low on-state resistance

·         Continuous Drain Current (ID) is 170mA

·         Drain Source Voltage (VDS) is 100V

·         On-state Resistance is 6Ω

·         Typical Gate threshold voltage (VGS-th) is 1.7V

·         Turn ON and Turn off delay time is 1.7ns and 17ns respectively

·         Available in SOT23 SMD package


Note: The complete technical information can be found at the datasheet given at the end of this page.

Alternative for BSS123: BSS138, NTR4003, 2N7002, FDC666, FDC558, BS170, 2N7000

Equivalent P-Channel for BSS123: BSS84, FDN358P

Other N-Channel Mosfet’s: BS170N, IRF3205, 2N7000, IRF1010E, IRF540N


BSS123 Description

The BSS123 is a compact Logic Level N-Channel Mosfet. The mosfet has very low threshold voltage of 01.7V and hence can be used with any low voltage application circuits and for level shifting applications. Adding to this the Mosfet also has low on-state resistance and low input capacitance which makes it efficient in switching circuits since it requires only less gate current even when switching at high speeds.

The BSS123 is slightly pricy for its specification, so if you are looking for a cheap alternative do check 2N7002. However you have to compensate slightly with the on-state resistance and threshold voltage of the Mosfet. This mosfet comes in a SMD package hence can be used for compact applications. One considerable disadvantage of the mosfet is its low drain current; it can provide a continuous current of 170mA and peaks currents upto 1A at maximum threshold voltage. Anything more than that will damage the mosfet.  You can also check the BSS1238 which has drain current of 200mA.


BSS123 Applications

·         Low current and Low Voltage switching applications

·         Logic Level Shifters

·         DC-DC converts

·         eMobility applications

·         Application where low on-state resistance is required.

·         Power management applications



The Mosfet is available in SOT23, the dimensions of the same is shown below.

 BSS123 Logic Level N Channel Mosfet 2-D Model


Component Datasheet

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