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onsemi 4N27SM — Optoisolators

4N27SM Optoisolator – onsemi, 4170 Vrms, 6-SMD Gull Wing

MPN4N27SM
End of Life

onsemi 4N27SM optoisolator, 1-channel DC input, transistor with base output, 4170 Vrms isolation, 6-SMD gull wing surface mount package, -40°C to 100°C, active production.

$0.64Ref. price · indicative, final on quote
onsemi 4N27SM datasheet (PDF)
Packaging6-SMD, Gull Wing
RoHSROHS3 Compliant
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

4N27SM specifications
ParameterValue
Input typeDC
Output typeTransistor with Base
MountingSurface Mount
Voltage - isolation4170Vrms
Voltage - output30V
Voltage - forward (Vf)1.18V
Current transfer ratio10% @ 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

Product details

4170 Vrms isolation in a 6-SMD gull-wing package

The 4N27SM is a single-channel optoisolator from onsemi, with a DC input driving a phototransistor with base access. Its 4170 Vrms isolation rating (cite:) provides a reinforced safety barrier for separating low-voltage control circuits from higher-voltage load sides — typical in motor drives, PLC I/O modules, and SMPS feedback loops. The 6-SMD gull-wing package (cite:) is surface-mountable, saving board space compared to through-hole DIP variants.

500 mV Vce saturation — load drop matters

Vce saturation is specified at 500 mV max at 10 mA forward current. This is the voltage the output transistor drops when fully on — higher than the 4N35SM's 300 mV, so at the same load current the 4N27SM dissipates more power. The 4N28SM shares the same 500 mV spec, making it a drop-in alternative if the 4N27SM is unavailable.

Industrial temperature range and switching speed

Typical turn-on and turn-off times are 2 µs each (cite:) — fast enough for 100 kHz switching or isolated data transmission at moderate rates. The base terminal allows external bias adjustment or Miller clamp, giving the designer control over switching behaviour.

Frequently asked questions

Can I replace a through-hole 4N27 with the 4N27SM surface-mount version?

Yes — the 4N27SM is the surface-mount variant of the 4N27, sharing the same die and electrical characteristics: 4170 Vrms isolation (cite:), 500 mV Vce saturation (cite:), and 2 µs switching times (cite:). The only difference is the 6-SMD gull-wing package (cite:) instead of a through-hole DIP. Your PCB layout must accommodate the surface-mount footprint; the pinout is identical.

Is the 4N27SM RoHS compliant?

Yes, the 4N27SM is ROHS3 compliant (cite:), meaning it meets the latest EU directive restricting lead, mercury, cadmium, and other hazardous substances.

What is the closest functional second-source to the 4N27SM?

The 4N28SM (cite:) is the nearest functional alternative — same 4170 Vrms isolation, same 500 mV Vce saturation, same package and pinout. The 4N35SM (cite:) offers a lower 300 mV Vce saturation but is otherwise interchangeable. Both are active onsemi parts and can be sourced through the same RFQ process.