4N31 Equivalent & Substitute Parts

Part Overview

The 4N31 is an optoisolator with Darlington output and base connection, manufactured by onsemi. It provides 5300Vrms isolation voltage in a single-channel 6-DIP package rated for through-hole mounting. The part is currently obsolete, making equivalent substitutes necessary for ongoing system support and new designs requiring compatible isolation solutions.

Substiute Parts

4N31

onsemiIn Stock: 34814N31 Datasheet

Current PartRFQ

4N30M

Fairchild SemiconductorIn Stock: 182084N30M Datasheet

SimilarRFQ

4N33M

Fairchild SemiconductorIn Stock: 138074N33M Datasheet

SimilarRFQ

4N46

Broadcom LimitedIn Stock: 48704N46 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 4N31 is determined by the following critical parameters:

• Isolation Voltage: Minimum 5000Vrms required to maintain equivalent isolation performance
• Output Type: Must be Darlington with Base configuration
• Number of Channels: Single channel only
• Package Type: 6-DIP through-hole mounting
• Input Type: DC input
• Operating Temperature Range: Must support -55°C to 100°C or equivalent industrial range

The substitute parts 4N30M, 4N33M, and 4N46 meet these core requirements with variations in current transfer ratio, output voltage rating, and switching characteristics.

Parameter Comparison

Engineering Selection Recommendations

4N30M (Fairchild Semiconductor): Active product status with 5000Vrms isolation voltage. Package dimensions differ (0.400" vs 0.300"), requiring PCB layout verification. Higher current transfer ratio (100% min) provides improved switching performance. Suitable for applications where the larger DIP footprint is accommodated.

4N33M (Fairchild Semiconductor): Active product status with 5000Vrms isolation voltage. Highest current transfer ratio (500% min) among substitutes, enabling faster switching response. Longer turn-off time (100µs max) compared to 4N31. Package dimensions differ (0.400" vs 0.300"), requiring PCB layout verification.

4N46 (Broadcom Limited): Active product status with matching 6-DIP (0.300", 7.62mm) package footprint. Isolation voltage reduced to 3750Vrms, suitable only for applications not requiring 5300Vrms isolation. Output voltage maximum of 20V is lower than 4N31 (30V). Operating temperature range limited to -40°C ~ 85°C. RoHS non-compliant status noted.

Frequently Asked Questions (FAQ)

Q: Can 4N30M or 4N33M be used as direct pin-for-pin replacements for 4N31?

A: Both parts have identical pin configurations and Darlington with Base output topology. However, package body dimensions differ (0.400" vs 0.300"), requiring PCB layout verification before substitution. Electrical performance is compatible within the specified parameter ranges.

Q: What is the isolation voltage difference between 4N31 and 4N46?

A: The 4N31 provides 5300Vrms isolation, while 4N46 provides 3750Vrms. The 4N46 is suitable only for applications where lower isolation voltage is acceptable. Applications requiring 5300Vrms isolation must use 4N30M or 4N33M.

Q: Why does 4N46 have a lower operating temperature maximum?

A: The 4N46 is rated for -40°C ~ 85°C, compared to 4N31's -55°C ~ 100°C. Applications requiring operation below -40°C or above 85°C must use 4N30M or 4N33M.

Q: How do current transfer ratios affect circuit performance?

A: Higher current transfer ratios (4N33M at 500% min, 4N46 at 200% min) provide greater output current for a given input current, enabling faster switching and reduced input drive requirements. The 4N31's 50% minimum ratio requires higher input current for equivalent output performance.

Q: Are there compliance differences between substitute parts?

A: 4N46 is RoHS non-compliant. All parts carry REACH Unaffected and EAR99 ECCN designations. Compliance requirements for your application determine acceptable substitutes.