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STMicroelectronics STP185N55F3 — Discrete Semiconductors

STP185N55F3 N-Channel MOSFET, 55V 120A TO-220, 3.8mOhm

MPNSTP185N55F3
Obsolete

STMicroelectronics STripFET™ STP185N55F3, N-Channel MOSFET, 55 V Vdss, 120 A Id, 3.8 mOhm Rds(on) @ 10 V, 100 nC Qg, TO-220-3, -55 to 175 °C.

$5.3800Ref. price · indicative, final on quote
PackagingTO-220-3
RoHSROHS3 Compliant
SeriesSTripFET™
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

STP185N55F3 specifications
ParameterValue
SeriesSTripFET™
FET typeN-Channel
MountingThrough Hole
Drain to source voltage55 V
Drive voltage (Max rds on, min rds on)10V
Current - continuous drain (Id) @ 25°C120A (Tc)
Power dissipation330W (Tc)
Operating temperature-55°C~175°C(TJ)
PackageTube
Vgs±20V
TechnologyMOSFET (Metal Oxide)
CaseTO-220-3
Vgs(th) (Max) @ id4V @ 250µA
Rds on (Max) @ id, vgs3.8mOhm @ 60A, 10V
Gate charge (Qg) (Max) @ vgs100 nC @ 10 V
Input capacitance (Ciss) (Max) @ vds6800 pF @ 25 V

Product details

Gate charge and switching — 100 nC at 10 V

Total gate charge is 100 nC at 10 V. That is a moderate figure for a 120 A device — the driver must supply about 1 A of peak current to hit a 100 ns rise time. For a 100 kHz SMPS, budget around 10 mA average gate drive current; a standard totem-pole driver handles it without a heatsink.

That extra headroom matters in downhole tools, avionics power stages, or any environment where the case temperature can push past 125°C. The 330 W power dissipation at case temperature assumes an infinite heatsink; real-world derating follows the RthJC of the TO-220 package — about 0.45 °C/W junction-to-case.

Obsolete — sourcing through the independent channel

ST has marked the STP185N55F3 as obsolete. Availability and pricing vary with market conditions; we source and quote each request to order against an RFQ, confirming current stock and price at quote time.

Frequently asked questions

Is STP185N55F3 obsolete and what is a direct replacement?

Yes, the STP185N55F3 is obsolete per ST's product status. No official direct replacement is listed by the manufacturer. For a pin-compatible alternative in the same TO-220 footprint, look for an N-channel MOSFET with similar 55 V Vdss, 120 A Id, and 3.8 mOhm Rds(on) ratings — several vendors offer parts in this performance tier. Confirm the gate charge and threshold voltage match your drive circuit before substituting.

What is the Rds(on) and Vgs(th) of STP185N55F3?

Maximum Rds(on) is 3.8 mOhm at 60 A drain current with 10 V gate drive. Maximum gate threshold voltage is 4 V at 250 µA drain current. The recommended drive voltage for minimum on-resistance is 10 V.