Type MOSFET Transistor | Working principle N-channel | |
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Pin configuration G = Gate, D = Drain, S = Source. The symbol doesn't always show the internal diode formed by the substrate connection source to drain | ||
The 2N7000 and BS170 are N-channel, enhancement-mode MOSFETs used for low-power switching applications. The two are nearly identical except that the leads are arranged differently and the current ratings are somewhat different; they are sometimes listed together on the same datasheet, along with other variants 2N7002, VQ1000J, and VQ1000P.
The 2N7000 is a widely available and popular part, often recommended as useful and common components to have around for hobbyist use, along with such other popular discrete semiconductors as the 1N4148 and 1N4001 diodes; the 2N2222, 2N3904, and 2N3906 bipolar junction transistors; and the IRF510 power MOSFET. The BS250P is "a good p-channel analog of the 2N7000."
Packaged in a TO-92 enclosure, both the 2N7000 and BS170 are 60 V devices, capable of switching 200 mA (2N7000) or 500 mA (BS170), with a maximum on-resistance of 5 Ω at 10 V Vgs.
The 2N7002 is a slightly higher resistance, lower current variant, in a TO-236 package, also known as "small outline transistor" SOT-23 surface-mount package, which is the most commonly used three-lead surface-mount package.
Applications
The 2N7000 has been referred to as a "FETlington" and as an "absolutely ideal hacker part." The word "FETlington" is a reference to the Darlington-transistor-like saturation characteristic.
A typical use of these transistors is as a switch for moderate voltages and currents, including as drivers for small lamps, motors, and relays. In switching circuits, these FETs can be used much like bipolar junction transistors, but have some advantages:
The main disadvantages of these FETs over bipolar transistors in switching are the following: