A P-channel power MOSFET in TO-220, the complement to the N-channel IRF540 and the usual choice for high-side switching and reverse-polarity protection. It blocks 100 V, carries up to 23 A, and turns on when the gate is pulled below the source, which is convenient for switching a load's positive rail from a ground-referenced control signal. Its on-resistance (about 0.20 ohm) is higher than an equivalent N-channel part, as is typical for P-channel devices. Pair it with an IRF540 to build an H-bridge or a complementary push-pull stage. The tab and pin 2 are the drain; pinout is G, D, S.

Pinout

Pin	Name	Type	Function
1	G	input	Gate. Insulated MOSFET gate; VGS(th) = -2.0 V to -4.0 V, absolute maximum VGS = ±20 V. Drive to ~-10 V (source-referenced) for full enhancement (RDS(on) = 0.20 Ω); total gate charge Qg = 61 nC.
2	D	passive	Drain. Power terminal, internally connected to the mounting tab. VDS breakdown = -100 V, continuous ID = -19 A (TC = 25 °C), pulsed IDM = -72 A. Body diode cathode returns to this pin.
3	S	passive	Source. Power return terminal for the P-channel MOSFET; body/source-drain diode anode. Same current rating as drain (-19 A continuous). Reference for VGS drive.

Key specifications

Parameter	Value
Type	P-channel power MOSFET
Drain-source (VDS)	-100 V
Continuous drain current (ID)	-23 A
RDS(on)	0.20 Ω at VGS=-10 V
Gate drive	standard (VGS=-10 V for full on)
Power dissipation	150 W
Tab	electrically Drain
Pinout	G-D-S
Package	TO-220

Ordering variants

Same part, different packaging or reel option.

IRF9540PbF (TO-220)
IRF9540 (TO-220, tube)

CAD (KiCad official)

Symbol: Transistor_FET:IRF9540N
Footprint: Package_TO_SOT_THT:TO-220-3_Vertical
3D model: TO-220 (KiCad packages3D)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Vishay Siliconix datasheet (7 pp, sha256 e95ccd4f3a9181e0, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF