ICBOMS
onsemi 4N26SM — Optoisolators
Technical Documents PDF / CAD
Download Datasheet (PDF) Preview ↓
RoHS Compliant · Lead-Free EIA-481 Standard
onsemi / Optoisolators

4N26SM Optoisolator – 4170Vrms, Transistor Output, onsemi

MPN 4N26SM
Active Spot Stock · 24-48h Dispatch 100% Original Sealed

onsemi 4N26SM, single-channel DC-input optocoupler with transistor base output, 4170Vrms isolation, 20% min CTR at 10mA, 2µs switching, in a 6-SMD gull-wing package.

In Stock: 3 pcs
MOQ: 1 pcs
Logistics: DHL / FedEx DAP (Global Express · 3-7d) Russia & CIS DDP (Door-to-Door Cleared)
Dispatch: Shenzhen / HK
Unit Price (USD)
$0.65 / pc
Direct Purchase Ready
Volume Pricing Breaks Confirmed upon quotation
1+ pcs
$0.65
Working on a production BOM or have a target unit price? Submit Target Price
Buy Now

$0.65 / ea

3 in stock — maximum per order · 3–4 days lead time
Upload Full BOM List
100% Original Sealed 45x Microscope QC 30-Day Warranty · COC USD T/T & PI · DAP/DDP
[SPEC] Essential Parameters Snapshot Full Specifications (14)
Package / Case 6-SMD, Gull Wing
ALT
Facing long factory lead times or allocation on 4N26SM? Verified pin-compatible alternatives available with active Shenzhen stock and 100% solder-ready footprint match.
View Pin Alternates (4)

Full Technical Specifications

14 Parameters
4N26SM specifications
Parameter / AttributeSpecification / Value
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-40°C ~ 100°C
PackageTube
Case6-SMD, Gull Wing
Channels1
Vce saturation500mV
Turn on (Turn off time)2µs, 2µs
100% Footprint Match · Solder-Ready (No PCB Redesign Needed)

Need Stock or a Drop-in Second-Source for 4N26SM?

Package: DIP-6 · Pin-compatible replacements with immediate Shenzhen spot stock

Footprint Match 98%
Supply Chain & Allocation Reality:

The 4N2x / 4N3x row is the general-purpose opto that predates the PC817 and still fills industrial boards, instruments and old audio gear: a 6-pin DIP with an infrared LED, a phototransistor, and one extra pin the 4-pin generation gave up - the base of the phototransistor, brought out for speed-up tricks and threshold trimming. The family is a CTR ladder wearing four part numbers: 4N25/26 at 20% minimum, 4N27/28 at 10%, and the 4N35/36/37 trio at 100% - one of the highest CTRs of any general-purpose opto, which is why it survives in circuits that need gain more than speed. Substituting within the row is honest work; substituting against the 4-pin PC817 row is the classic socket error.

Verified Pin-Compatible Replacements (4 verified alternatives)

4N25 onsemi / Vishay / Everlight DIP-6
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

The 20% Rung - Same Socket, Real Numbers

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The 20% minimum CTR member at 10mA LED current (same bin as the 4N26): the everyday grade of the row, pin-identical to every 4N2x and 4N3x part.

Standard 6-pin opto envelope: 5.3kV-class isolation in the classic parts, 30V-class collector-emitter ratings, pin 6 base exposed.

Compatibility & Drop-In Notes: Substitution inside the row must carry the CTR requirement: a 4N25 (20%) is a genuine downgrade from a 4N35 (100%) in any circuit that relied on the gain - the LED drive may need recomputing. The reverse is free margin.
Package & Solder Footprint: Standard 6-pin DIP; pinout 1 anode, 2 cathode, 3 NC, 4 emitter, 5 collector, 6 base.
Shenzhen Warehouse Stock & MOQ: Stocked across the row; the differences are documented per grade.
Request Volume Quote for 4N25 Compare 4N26SM vs 4N25 Spec Matrix
4N37 Everlight / Vishay / onsemi DIP-6
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

The 100% CTR Rung

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The high-gain member of the row: 100% minimum CTR at 10mA (40% guaranteed across the full temperature range), the reason it appears wherever the driving current must stay small.

Same envelope; isolation figure per the vendor grade (5.3kV class in the classic datasheets).

Compatibility & Drop-In Notes: The honest substitution sentence for this row: going up in CTR is always electrically kind; going down needs the drive budget re-derived - the 10mA figure in the datasheet assumes the LED the original design budgets for.
Package & Solder Footprint: Identical 6-pin DIP footprint.
Shenzhen Warehouse Stock & MOQ: Stocked as the high-gain repair part for marginal-drive circuits.
Request Volume Quote for 4N37 Compare 4N26SM vs 4N37 Spec Matrix
H11A1 Vishay / onsemi (legacy) DIP-6
Functional Equivalent
Availability & Target Pricing:

The Ancestor Row

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The 6-pin row the 4N parts were defined alongside: H11A1 at 50% minimum CTR, H11A5 at 30% - same socket and base pin, its own gain ladder.

Same envelope and isolation class.

Compatibility & Drop-In Notes: In equipment documentation, a service manual often names the H11A part while the board carries a 4N one (or the reverse): the numbers are what matter, the names are lineage.
Package & Solder Footprint: Standard 6-pin DIP pinout.
Shenzhen Warehouse Stock & MOQ: Stocked for legacy equipment; verify markings on older lots.
Request Volume Quote for H11A1 Compare 4N26SM vs H11A1 Spec Matrix
PC817 Sharp / multiple DIP-4
Functional Equivalent
Availability & Target Pricing:

The 4-Pin Cousin - Different Socket

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The 4-pin general-purpose opto of the next generation: same phototransistor idea without the base pin, and its own CTR rank system (A/B/C/D) that replaced the 4N CTR ladder in new designs.

Same functional envelope; 5kV-class isolation in the modern parts.

Compatibility & Drop-In Notes: When a service note says "PC817 replaces 4N35", it means functionally in some circuits - the socket does not agree. Fitting a 4-pin part into a 6-pin footprint needs the adapter or a new layout, and the base-pin behavior is gone either way.
Package & Solder Footprint: DIP-4 against DIP-6: different footprint by construction.
Shenzhen Warehouse Stock & MOQ: The modern volume part; see its own page for the rank system.
Request Volume Quote for PC817 Compare 4N26SM vs PC817 Spec Matrix
Buyer & Quality Checklist for Sourcing Alternatives
  • The CTR minimum is the specification: 4N25/4N26 = 20%, 4N27/4N28 = 10%, 4N35/4N36/4N37 = 100% (40% across the extended range). The 4N3x trio is the same sockets at five times the gain - the direction of every substitution follows this number.
  • Pin 6 (base) distinguishes this row from the 4-pin generation: a base-emitter resistor speeds the transistor up (trading gain for bandwidth), and a small bias trims the threshold. Designs that used it detect a replacement without it immediately - noise and edge behavior change.
  • The 4-pin PC817 row is not the same socket: no base pin, a different rank system (A-D), and a modern isolation class. Functionally comparable in many circuits, mechanically incompatible without an adapter.
  • LED drive is part of the gain budget: the CTR numbers assume 10mA of LED current. A circuit that halved its LED drive for efficiency cannot expect the original switching thresholds from the same grade.
  • The classic 6-pin bodies carry 5.3kV-class isolation figures - verify per vendor and grade; clone rows trade here first.
  • For repair of old gear, read the service manual part against the row: the H11A names and the 4N names cross freely in tables, and the CTR number is the only thing that transfers between them.
Frequently Asked Technical Questions

Q: What is the difference between 4N25 and 4N35?

A: Current transfer ratio: 4N25 is 20% minimum, 4N35 is 100% minimum (40% guaranteed over the extended temperature range). Same 6-pin socket and pinout; the 4N3x part is the high-gain version of the same design.

Q: What is pin 6 on a 4N35 used for?

A: The phototransistor base, brought out for design freedom: a base-emitter resistor speeds up switching, a small bias trims the effective threshold. It is also the physical difference from the 4-pin opto generation.

Q: Can I replace a 4N35 with a PC817?

A: Functionally similar in many circuits, but not socket-compatible - the PC817 is a 4-pin part without the base pin. Fitting one needs an adapter or a new layout, and the base-pin behavior is lost either way.

Technical Details & Description

Isolation barrier and output drive

The 4N26SM is a single-channel optocoupler from onsemi with a DC input and a phototransistor output that brings the base terminal out. The typical forward voltage of 1.18V and maximum forward current of 60mA define the input-side resistor and LED current budget.

Switching speed and saturation

Turn-on and turn-off times are both 2µs typical, which limits the usable signalling rate to roughly 250 kbps before pulse-width distortion becomes significant. The 500mV maximum Vce saturation at the output ensures low voltage drop when the transistor is on, keeping power dissipation in the output stage manageable. Compared to the 4N35SM, which specifies a 300mV Vce saturation, the 4N26SM has a higher saturation ceiling — a consideration when driving loads near the 30V output maximum where headroom is tighter.

Package, temperature range, and compliance

The 4N26SM is supplied in a tube of surface-mount 6-SMD gull-wing packages.

Frequently asked questions

What is the current transfer ratio (CTR) of the 4N26SM?

The minimum CTR is 20% at 10mA forward current. At 10mA LED drive, the output transistor can sink at least 2mA.

What is the difference between the 4N26 and the 4N26SM?

The 4N26 is the through-hole DIP version; the 4N26SM is the surface-mount gull-wing variant. All electrical specifications are identical.

Is the 4N26SM RoHS compliant?

Yes, the 4N26SM is ROHS3 compliant per onsemi's lifecycle data.

4N26SM
Verified Allocation
Quote