3N138 MOSFET 35V N-Channel
The 3N138 is a 35 V N‑Channel MOSFET designed to switch low‑voltage loads efficiently, useful in projects with 12/24 V LED strips, small DC motors, valves or relays; imagine you want to turn on a 12 V pump with a microcontroller: connect the source (S) to GND, the drain (D) to the negative side of the pump and the positive side of the pump to +12 V, then drive the gate (G) from the micro’s pin via a 100–220 Ω resistor, adding a ~100 kΩ pull‑down resistor to GND to keep it off at start‑up and, if the load is inductive, a flyback diode (e.g. 1N5819 or 1N4007) in antiparallel across the load to protect against overvoltage; with a maximum drain‑source voltage of 35 V the device suits 5–24 V systems, but check the datasheet to see if it is “logic‑level” (so the gate is driven well at 3.3–5 V) or if a dedicated driver is required, and remember that the maximum gate‑to‑source voltage typically ranges up to ±20 V: do not exceed it; for efficiency a low Rds(on) matters, because losses are estimated with P ≈ I²·Rds(on), so, if the load draws a lot of current or the MOSFET gets hot, plan for a heatsink or a good copper area; small numerical example: for a 12 V, 2 A LED strip, choose a 3N138 with Rds(on) of a few milliohms, expecting losses below 0.5 W and temperature under control with a well‑dissipating PCB; good practice: common ground between power and logic, short track to the load, an optional 12–15 V Zener between gate and source for protection, and respect the SOA if you use fast PWM; with these precautions the 3N138 35 V N‑Channel MOSFET becomes a solid, silent and efficient switch for your projects.
Specifications:
| Drain Current-Max (Abs) (ID) | 0.05 A |
| Drain Current-Max (ID) | 0.05 A |
| Drain-source On Resistance-Max | 350.0 ohm |
| DS Breakdown Voltage-Min | 35.0 V |
| FET Technology | METAL-OXIDE SEMICONDUCTOR |
| JEDEC-95 Code | TO-72 |
