4N25SD Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N25SD is a single-channel optoisolator transistor with base output manufactured by onsemi, rated for 5300Vrms isolation voltage in a 6-SMD surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The 4N25SD operates across a temperature range of -55°C to 100°C with a 20% minimum current transfer ratio at 10mA input current and 500mV maximum Vce saturation.

Key Parameters

Parameter	Value
Manufacturer	onsemi
Part Number	4N25SD
Category	Optoisolators
Number of Channels	1
Voltage - Isolation	5300Vrms
Current Transfer Ratio (Min)	20% @ 10mA
Turn On / Turn Off Time (Typ)	2µs, 2µs
Output Type	Transistor with Base
Voltage - Output (Max)	30V
Voltage - Forward (Vf) (Typ)	1.18V
Current - DC Forward (If) (Max)	100 mA
Vce Saturation (Max)	500mV
Operating Temperature	-55°C ~ 100°C
Mounting Type	Surface Mount
Package / Case	6-SMD, Gull Wing
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the 4N25SD is determined by the following critical parameters:

Isolation Voltage Rating: The 4N25SD specifies 5300Vrms isolation. Substitute parts must maintain isolation voltage at or above this level to ensure electrical safety and regulatory compliance.
Output Configuration: All substitutes must feature transistor output with base connection to maintain circuit compatibility.
Package Type: All substitutes must use 6-SMD, Gull Wing surface mount packaging for PCB layout compatibility.
Current Transfer Ratio: Minimum 20% @ 10mA is required for functional equivalence.
Operating Temperature Range: Substitutes must support the full -55°C to 100°C operating range.
Vce Saturation: Maximum 500mV saturation voltage is required for output switching performance.

Substitute parts are grouped into two categories:

Direct Substitutes (Isolation ≥ 5000Vrms): Parts meeting or exceeding the 5300Vrms isolation specification, including 4N25SR2M (4170Vrms), 4N25-X007T (5000Vrms), 4N25-X009T (5000Vrms), and 4N25-X017 (5000Vrms).

Functional Alternatives (Isolation < 5000Vrms): Parts with reduced isolation voltage (2500Vrms) including 4N25-300E, 4N25-500E, 4N25S-TA, and 4N25S-TA1. These are suitable only when circuit isolation requirements permit lower voltage ratings.

Parameter Comparison

Part Number	Manufacturer	Isolation Voltage	CTR (Min)	Turn On/Off Time	Output Type	Vout (Max)	Vf (Typ)	If (Max)	Vce Sat (Max)	Temp Range	Package	Status
4N25SD	onsemi	5300Vrms	20% @ 10mA	2µs, 2µs	Transistor w/ Base	30V	1.18V	100mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Obsolete
4N25SR2M	onsemi	4170Vrms	20% @ 10mA	2µs, 2µs	Transistor w/ Base	30V	1.18V	60mA	500mV	-40°C ~ 100°C	6-SMD, Gull Wing	Active
4N25-X007T	Vishay Semiconductor Opto Division	5000Vrms	20% @ 10mA	2µs, 2µs	Transistor w/ Base	70V	1.36V	60mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25-X009T	Vishay Semiconductor Opto Division	5000Vrms	20% @ 10mA	2µs, 2µs	Transistor w/ Base	70V	1.36V	60mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25-X017	Vishay Semiconductor Opto Division	5000Vrms	20% @ 10mA	2µs, 2µs	Transistor w/ Base	70V	1.36V	60mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25S	onsemi	5300Vrms	20% @ 10mA	2µs, 2µs	Transistor w/ Base	30V	1.18V	100mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Obsolete
4N25S-TA	Lite-On Inc.	2500Vrms	20% @ 10mA	—	Transistor w/ Base	30V	1.2V	80mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25S-TA1	Lite-On Inc.	2500Vrms	20% @ 10mA	—	Transistor w/ Base	30V	1.2V	80mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25-300E	Broadcom Limited	2500Vrms	20% @ 10mA	—	Transistor w/ Base	30V	1.2V	80mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25-500E	Broadcom Limited	2500Vrms	20% @ 10mA	—	Transistor w/ Base	30V	1.2V	80mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active
4N25SMT&R	Isocom Components 2004 LTD	7.5Vpk	20% @ 10mA	2µs, 2µs	Transistor w/ Base	30V	1.2V	60mA	500mV	-55°C ~ 100°C	6-SMD, Gull Wing	Active

Engineering Selection Recommendations

For Direct Replacement (Equivalent Isolation Performance):

The 4N25-X007T and 4N25-X009T from Vishay Semiconductor Opto Division are the primary active substitutes, both rated at 5000Vrms isolation with full -55°C to 100°C temperature support and ROHS3 compliance. These parts maintain the 2µs switching time specification and support the required 20% minimum current transfer ratio. The 4N25-X017 variant offers identical electrical specifications in tube packaging.

The 4N25SR2M from onsemi provides an active alternative with 4170Vrms isolation, though it operates at a reduced lower temperature limit of -40°C and supports only 60mA maximum forward current compared to the 4N25SD's 100mA specification.

For Reduced Isolation Applications:

When circuit design permits isolation voltage reduction to 2500Vrms, the 4N25S-TA1 (Lite-On Inc.) and 4N25-300E (Broadcom Limited) are active production parts with ROHS3 compliance and full temperature range support. Both support 80mA maximum forward current and maintain 500mV Vce saturation.

Product Status Considerations:

The 4N25S and 4N25SD are both classified as obsolete. Active production alternatives ensure long-term supply chain stability and compliance with current manufacturing standards. All recommended active substitutes carry ROHS3 compliance and REACH unaffected status.

Frequently Asked Questions (FAQ)

Q: Can the 4N25SR2M replace the 4N25SD directly?

A: The 4N25SR2M is electrically compatible for most applications but operates at a reduced lower temperature limit (-40°C vs. -55°C) and supports only 60mA maximum forward current versus the 4N25SD's 100mA. Verify your circuit's temperature and current requirements before substitution.

Q: What is the difference between 4N25-X007T and 4N25-X009T?

A: Both parts are rated at 5000Vrms isolation with identical electrical specifications. The primary difference is packaging: 4N25-X007T is supplied in Tape & Reel format, while 4N25-X009T is also supplied in Tape & Reel. Consult packaging requirements for your procurement process.

Q: Can I use a 2500Vrms part (4N25S-TA1) in place of the 5300Vrms 4N25SD?

A: Only if your circuit design permits reduced isolation voltage. The 4N25S-TA1 maintains all other electrical parameters (20% CTR, 500mV Vce saturation, -55°C to 100°C operation) but provides significantly lower isolation rating. This substitution is not suitable for high-voltage isolation applications.

Q: What packaging options are available for active substitutes?

A: The 4N25-X007T, 4N25-X009T, and 4N25-X017 are supplied in Tape & Reel or Tube packaging. The 4N25SR2M is available in Cut Tape (CT) & Digi-Reel format. The 4N25S-TA1 is supplied in Cut Tape (CT) & Digi-Reel format. Verify packaging compatibility with your assembly process.

Q: Are all active substitutes RoHS compliant?

A: Yes. All active substitute parts listed carry ROHS3 compliance certification. The obsolete 4N25SD and 4N25S do not have RoHS status specified.

Q: What is the minimum current transfer ratio for all listed parts?

A: All parts, including the 4N25SD and all substitutes, maintain a minimum 20% current transfer ratio at 10mA input current, ensuring functional equivalence in this critical parameter.

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