P-channel MOSFET (AO3401, IRF9540N, AOD4185, TO-92)
AO3401 · TO-92 (SOT-23 on a carrier) · V_GS(th) ≈ −0.9 V · 4 A · −30 V · turns on when the gate is pulled below the source
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Pins
- G
- D
- S
Ratings and limits
| V_DS | −30 V |
|---|---|
| I_D | 4 A |
| V_GS(th) | ≈ −0.9 V |
| Package | TO-92 (SOT-23 on a carrier) |
How to use it
A high-side switch: source to the positive supply, gate pulled below the source to turn on. Wired backwards in a supply lead it makes reverse-polarity protection with almost no voltage drop.
Lessons and builds that use it
- Ideal-diode OR-ing: USB plus battery
- Reverse-polarity protection with a P-MOSFET
- Class-D amplifier from parts
- 65 W USB-C PD stage on a ready-made 24 V supply: buck converter, PD controller, load switch (build)
- 65 W USB-C PD charger from scratch: mains flyback (UC3844, 800 V MOSFET, PQ2625 transformer), TL431 + PC817 feedback, PD controller (build)
- Real device: phone charger, 220 V AC wall to 5 V USB (build)
- Real device: laptop charger, 220 V AC wall to 20 V with PFC (build)