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onsemi 4N25SM — Optoisolators

4N25SM Optoisolator, 4170Vrms, Transistor Output, onsemi

MPN4N25SM
Active

onsemi 4N25SM, single-channel DC-input optoisolator, 4170Vrms isolation, transistor with base output, 6-SMD gull-wing surface-mount package, tube packaging.

$0.7400Ref. price · indicative, final on quote
onsemi 4N25SM datasheet (PDF)
Packaging6-SMD, Gull Wing
RoHSROHS3 Compliant
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

4N25SM specifications
ParameterValue
Input typeDC
Output typeTransistor with Base
MountingSurface Mount
Voltage - isolation4170Vrms
Voltage - output30V
Voltage - forward (Vf)1.18V
Current transfer ratio20% @ 10mA
Current - DC forward (If)60 mA
Operating temperature-55°C ~ 100°C
PackageTube
Case6-SMD, Gull Wing
Channels1
Vce saturation500mV
Turn on (Turn off time)2µs, 2µs

Product details

Isolation and switching for field-fit

The 4N25SM is a single-channel optoisolator from onsemi, rated for 4170Vrms isolation between input and output. The transistor output with base access gives you flexibility to bias the transistor for faster switching or to pull the base low to force the output off.

Current transfer ratio and drive margin

Minimum current transfer ratio is 20% at 10mA forward current. That means with 10mA through the LED, the output transistor can sink at least 2mA. If your downstream load needs more, you either increase the LED current (up to 60mA max) or pick a part with higher CTR. The 4N35SM sibling drops Vce saturation to 300mV versus 500mV here, which matters if you are driving a low-voltage logic input directly.

The 6-SMD gull-wing package reflows on a standard profile, but note it ships in a tube — not tape-and-reel.

Frequently asked questions

What are the equivalents or substitutes for 4N25SM?

The 4N25SR2M is the same die in tape-and-reel. The 4N28SM is a functional equivalent with the same isolation and switching speed but a different base-product number. The 4N35SM offers a lower Vce saturation of 300mV versus 500mV, which helps when driving 3.3V logic directly.

Is 4N25SM surface mount?

Yes, 6-SMD gull-wing package. Reflow-solderable on a standard profile. The tube packaging means you need a tube feeder or hand-place for prototypes.

What is the Vce saturation of 4N25SM?

500mV maximum at the rated forward current. That is the voltage drop across the output transistor when it is on — budget that into your logic-low threshold.