4N27SD Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N27SD is a single-channel optoisolator with transistor output and base connection, manufactured by onsemi. It provides 5300Vrms isolation voltage in a 6-SMD surface mount package. The part is currently obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. Substitute parts must maintain compatibility across isolation voltage, output configuration, switching characteristics, and thermal operating range.

Key Parameters

Parameter	4N27SD
Manufacturer	onsemi
Category	Optoisolators
Number of Channels	1
Voltage - Isolation	5300Vrms
Current Transfer Ratio (Min)	10% @ 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
Input Type	DC
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the 4N27SD is determined by the following critical parameters:

Primary Compatibility Criteria:

Single-channel configuration with transistor output and base connection
6-SMD surface mount package with gull wing leads
DC input type
Operating temperature range of -55°C to 100°C minimum
Vce saturation maximum of 500mV
Current transfer ratio minimum of 10% @ 10mA

Isolation Voltage Grouping: Substitute parts are categorized by isolation voltage rating. Parts with 5000Vrms or higher isolation voltage (4N27-X007, 4N27-X009T, 4N27-X017T, 4N27XSM) are direct functional equivalents to the 4N27SD at 5300Vrms. The 4N27SR2M at 4170Vrms provides reduced isolation but maintains all other electrical characteristics. Parts with significantly lower isolation voltage (4N27S-TA, 4N27S-TA1 at 1500Vrms) are suitable only for applications with lower isolation requirements.

Output Voltage and Current Considerations: The 4N27SD specifies 30V maximum output voltage and 100mA maximum forward current. Substitute parts with higher output voltage ratings (4N27-X007, 4N27-X009T, 4N27-X017T at 70V) and current ratings (50mA) remain compatible for applications within the 4N27SD's specified limits.

Parameter Comparison

Parameter	4N27SD	4N27SR2M	4N27-X007	4N27-X009T	4N27-X017T	4N27XSM	4N27S	4N27S-TA	4N27S-TA1	4N27SMT&R
Manufacturer	onsemi	Fairchild Semiconductor	Vishay Semiconductor Opto Division	Vishay Semiconductor Opto Division	Vishay Semiconductor Opto Division	Isocom Components 2004 LTD	onsemi	Lite-On Inc.	Lite-On Inc.	Isocom Components 2004 LTD
Voltage - Isolation	5300Vrms	4170Vrms	5000Vrms	5000Vrms	5000Vrms	5300Vrms	5300Vrms	1500Vrms	1500Vrms	7.5Vpk
Current Transfer Ratio (Min)	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA	10% @ 10mA
Turn On / Turn Off Time (Typ)	2µs, 2µs	2µs, 2µs	—	—	—	—	2µs, 2µs	—	—	—
Rise / Fall Time (Typ)	—	—	2µs, 2µs	2µs, 2µs	2µs, 2µs	2µs, 2µs	—	3µs, 3µs	3µs, 3µs	2µs, 2µs
Output Type	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base
Voltage - Output (Max)	30V	30V	70V	70V	70V	30V	30V	30V	30V	30V
Current - Output / Channel	—	—	50mA	50mA	50mA	50mA	—	100mA	100mA	50mA
Voltage - Forward (Vf) (Typ)	1.18V	1.18V	1.36V	1.36V	1.36V	1.2V	1.18V	1.2V	1.2V	1.2V
Current - DC Forward (If) (Max)	100 mA	60 mA	60 mA	60 mA	60 mA	60 mA	100 mA	80 mA	80 mA	60 mA
Vce Saturation (Max)	500mV	500mV	500mV	500mV	500mV	500mV	500mV	500mV	500mV	500mV
Operating Temperature	-55°C ~ 100°C	-40°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing
Product Status	Obsolete	Active	Active	Active	Active	Active	Obsolete	Active	Active	Active

Engineering Selection Recommendations

High Isolation Voltage Equivalents (5000Vrms and above): The 4N27-X007, 4N27-X009T, and 4N27-X017T from Vishay Semiconductor Opto Division are functionally equivalent to the 4N27SD, all rated at 5000Vrms isolation. These parts are active products with RoHS3 compliance and unlimited moisture sensitivity level. The 4N27-X009T and 4N27-X017T are available in Tape & Reel packaging with higher inventory levels (12,590 and 12,850 units respectively). The 4N27XSM from Isocom Components maintains the 5300Vrms isolation rating and is available in Tube packaging with active product status and RoHS3 compliance.

Matched Isolation Voltage Alternative: The 4N27S from onsemi provides identical 5300Vrms isolation and electrical characteristics to the 4N27SD but is also obsolete. This part is suitable only if legacy design continuity is required.

Reduced Isolation Voltage Option: The 4N27SR2M from Fairchild Semiconductor operates at 4170Vrms isolation, which is lower than the 4N27SD specification. This part is active and maintains all other electrical parameters including 2µs switching times and 500mV Vce saturation. Selection of this part requires confirmation that the application does not require the full 5300Vrms isolation rating.

Lower Isolation Voltage Alternatives: The 4N27S-TA and 4N27S-TA1 from Lite-On Inc. are rated at 1500Vrms isolation and are suitable only for applications with significantly reduced isolation requirements. These parts are active products with RoHS3 compliance and offer 100mA maximum forward current capability.

Packaging Considerations: The 4N27-X009T and 4N27-X017T are supplied in Tape & Reel format, suitable for automated assembly. The 4N27SR2M is supplied in Bulk packaging. The 4N27-X007 and 4N27XSM are supplied in Tube packaging. Selection should align with production assembly requirements and inventory management practices.

Frequently Asked Questions (FAQ)

Q: Can the 4N27SR2M be used as a direct replacement for the 4N27SD? A: The 4N27SR2M is electrically compatible in all parameters except isolation voltage. It operates at 4170Vrms compared to the 4N27SD's 5300Vrms. Use this part only if your application does not require the full isolation voltage specification of the original design.

Q: What is the difference between the Vishay 4N27-X007, 4N27-X009T, and 4N27-X017T parts? A: These three parts are electrically identical, all rated at 5000Vrms isolation with identical electrical characteristics. The primary difference is packaging: 4N27-X007 is supplied in Tube, while 4N27-X009T and 4N27-X017T are supplied in Tape & Reel format. Choose based on your assembly process requirements.

Q: Why is the 4N27SMT&R listed as a substitute if its isolation voltage is only 7.5Vpk? A: The 4N27SMT&R is included in the substitute list but is not recommended for applications requiring the 5300Vrms isolation of the 4N27SD. This part is suitable only for low-voltage isolation applications and should be selected only if isolation voltage requirements are significantly lower than the original design.

Q: Are all substitute parts RoHS compliant? A: The Vishay parts (4N27-X007, 4N27-X009T, 4N27-X017T) and Lite-On parts (4N27S-TA, 4N27S-TA1) are RoHS3 compliant. The Isocom 4N27XSM is RoHS3 compliant. The Fairchild 4N27SR2M and onsemi 4N27S do not list RoHS status in the provided specifications. Verify RoHS compliance requirements with your procurement specifications.

Q: What is the moisture sensitivity level for these parts? A: All parts listed maintain MSL 1 (Unlimited) moisture sensitivity level, indicating no special moisture handling requirements during storage or assembly.

Q: Can I use the 4N27S-TA or 4N27S-TA1 in place of the 4N27SD? A: These Lite-On parts operate at only 1500Vrms isolation, significantly lower than the 4N27SD's 5300Vrms. Use these parts only if your application has been redesigned for lower isolation voltage requirements. They are not suitable as direct replacements for high-isolation applications.

Q: What is the operating temperature range difference between the 4N27SR2M and other substitutes? A: The 4N27SR2M operates from -40°C to 100°C, which is narrower than the 4N27SD's -55°C to 100°C range. If your application requires operation below -40°C, the 4N27SR2M is not suitable. All other substitute parts maintain the full -55°C to 100°C operating range.

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