4N37TM Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N37TM is a single-channel optoisolator with transistor output and base connection, manufactured by onsemi. It provides 4170Vrms isolation voltage in a 6-DIP through-hole package. The part is currently listed as obsolete, making equivalent substitutes necessary for ongoing design support and procurement.

Substiute Parts

4N37TM

onsemiIn Stock: 8674N37TM Datasheet

Current PartRFQ

4N37G

Isocom Components 2004 LTDIn Stock: 9244N37G Datasheet

SimilarRFQ

4N37M

onsemiIn Stock: 43384N37M Datasheet

SimilarRFQ

4N37TVM

Fairchild SemiconductorIn Stock: 24324N37TVM Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 4N37TM is determined by the following critical parameters:

• Isolation Voltage: 4170Vrms minimum
• Number of Channels: 1 channel
• Output Type: Transistor with Base
• Package / Case: 6-DIP through-hole configuration
• Current Transfer Ratio: 100% @ 10mA minimum
• Voltage - Output (Max): 30V
• Vce Saturation (Max): 300mV

Substitute parts must match or exceed these specifications. Parts are grouped by electrical compatibility and product status availability.

Parameter Comparison

Engineering Selection Recommendations

4N37TVM (Fairchild Semiconductor): Direct electrical equivalent with identical isolation voltage (4170Vrms), current transfer ratio, output voltage, and timing specifications. Active product status ensures ongoing availability. Identical 6-DIP (0.400", 10.16mm) package footprint. Suitable for direct replacement in existing designs.

4N37M (onsemi): Maintains all critical electrical parameters matching the 4N37TM, including 4170Vrms isolation and 100% CTR @ 10mA. Active product status with ROHS3 compliance. Package dimension differs at 6-DIP (0.300", 7.62mm), requiring PCB layout verification before substitution.

4N37G (Isocom Components 2004 LTD): Meets core functional requirements with transistor output, base connection, and 30V maximum output voltage. Isolation voltage specified as 7.5Vpk differs from the 4170Vrms specification of the main part. Extended operating temperature range (-55°C ~ 100°C). Active product status with ROHS3 compliance. Suitable only for applications where lower isolation voltage is acceptable.

Frequently Asked Questions (FAQ)

Q: Can 4N37TVM replace 4N37TM directly? A: Yes. The 4N37TVM provides identical electrical specifications including 4170Vrms isolation voltage, 100% current transfer ratio, and matching package dimensions (6-DIP 0.400"). No design modifications are required.

Q: What is the key difference between 4N37M and 4N37TM? A: Electrical specifications are equivalent. The 4N37M uses a 6-DIP (0.300", 7.62mm) package versus the 4N37TM's 6-DIP (0.400", 10.16mm). PCB footprint compatibility must be confirmed before substitution.

Q: Is 4N37G a suitable replacement? A: The 4N37G meets functional requirements for transistor output optoisolators but specifies 7.5Vpk isolation voltage instead of 4170Vrms. Use only in applications where the lower isolation specification is acceptable.

Q: Why is the 4N37TM listed as obsolete? A: The 4N37TM is no longer in active production. Active alternatives (4N37TVM, 4N37M, 4N37G) provide equivalent or superior specifications and ensure long-term supply chain availability.

Q: Are all substitutes through-hole mounted? A: Yes. All listed substitutes use through-hole mounting in 6-DIP packages, maintaining compatibility with existing PCB designs.

Q: What compliance certifications apply to these parts? A: 4N37TVM and 4N37M carry ROHS3 compliance. All parts are REACH Unaffected and classified as EAR99 for export control purposes.