4N32 Optoisolator Darlington with Base - Equivalent & Substitute Parts

Part Overview

The 4N32 is a single-channel optoisolator with Darlington output and base connection, rated for 5300Vrms isolation voltage. This component is classified as obsolete by the original manufacturer (onsemi), making substitute part identification essential for ongoing production and maintenance applications. The 4N32 provides galvanic isolation in applications requiring high voltage separation with moderate current output capability.

Substiute Parts

4N32

onsemiIn Stock: 1527034N32 Datasheet

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4N32M

onsemiIn Stock: 224684N32M Datasheet

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4N32

Vishay Semiconductor Opto DivisionIn Stock: 1526684N32 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 4N32 are identified based on the following critical parameters that determine functional compatibility:

• Package / Case: 6-DIP (0.300", 7.62mm) — mechanical and pin compatibility requirement
• Number of Channels: 1 — functional requirement
• Output Type: Darlington with Base — circuit topology requirement
• Voltage - Isolation: 5300Vrms or higher — isolation rating must meet or exceed original specification
• Current Transfer Ratio (Min): 500% @ 10mA — optical coupling efficiency
• Voltage - Output (Max): 30V — output voltage rating
• Current - Output / Channel: 150mA or higher — output current capability
• Input Type: DC — input signal type
• Mounting Type: Through Hole — assembly compatibility

Substitutes are grouped into two categories: direct equivalents from alternative manufacturers and compatible variants with modified isolation ratings or output current specifications.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: 4N32M (onsemi)

The 4N32M is the recommended substitute for the obsolete 4N32. This part maintains active product status with onsemi, ensuring ongoing availability and supply chain reliability. The 4N32M is ROHS3 compliant, meeting modern environmental and regulatory requirements. The isolation voltage is reduced to 4170Vrms compared to the original 5300Vrms specification. This reduction is acceptable only in applications where the lower isolation rating satisfies system requirements. All other electrical parameters—current transfer ratio, output voltage, output current, and saturation voltage—remain equivalent to the original 4N32.

Alternative Substitute: 4N32 (Vishay Semiconductor Opto Division)

The Vishay 4N32 provides identical isolation voltage (5300Vrms) and operating temperature range (-55°C ~ 100°C) to the onsemi original. However, this part is also classified as obsolete. The output current capability is reduced to 100mA compared to the original 150mA specification, and the maximum forward current is limited to 60mA versus 80mA. This variant is suitable only for applications with reduced output current requirements. The Vishay part is ROHS3 compliant and REACH unaffected.

Selection Criteria:

• If isolation voltage of 5300Vrms is mandatory and output current of 150mA is required, neither substitute fully meets all original specifications. Evaluate application requirements against reduced isolation (4N32M) or reduced output current (Vishay 4N32).
• If isolation voltage can be reduced to 4170Vrms and output current of 150mA is required, select 4N32M for active product status and supply availability.
• If isolation voltage of 5300Vrms is required but output current can be reduced to 100mA, select Vishay 4N32.
• All substitutes maintain 6-DIP package compatibility and Darlington with base output topology.

Frequently Asked Questions (FAQ)

Q: Can the 4N32M be used as a direct replacement for the 4N32?

A: The 4N32M is mechanically and functionally compatible in terms of package, pin configuration, and output topology. The primary difference is the reduced isolation voltage rating (4170Vrms versus 5300Vrms). Substitution is valid only if your application does not require the full 5300Vrms isolation specification.

Q: What is the impact of reduced isolation voltage when using the 4N32M?

A: Isolation voltage determines the maximum voltage differential that can be safely applied across the optoisolator without risk of electrical breakdown. If your circuit design requires 5300Vrms isolation, the 4N32M with 4170Vrms rating does not meet this requirement. If your application operates at lower voltage differentials, the 4N32M provides adequate isolation.

Q: Why does the Vishay 4N32 have lower output current (100mA) than the original?

A: Output current capability is determined by the Darlington transistor design and thermal characteristics. The Vishay variant is specified for 100mA maximum output current per channel, compared to 150mA for the onsemi original. Applications requiring output currents above 100mA cannot use the Vishay part.

Q: Are all three parts pin-compatible?

A: Yes. The 4N32 (onsemi), 4N32M (onsemi), and 4N32 (Vishay) all use the 6-DIP (0.300", 7.62mm) package with identical pin assignments. Direct socket substitution is mechanically possible without PCB modification.

Q: What is the difference between the onsemi 4N32 and 4N32M in terms of compliance?

A: The 4N32M is ROHS3 compliant, while the original 4N32 compliance status is not specified in the provided data. The 4N32M is the preferred choice for applications requiring RoHS compliance. Both parts are REACH unaffected.

Q: Can I use the Vishay 4N32 if I need 5300Vrms isolation but lower output current?

A: Yes. If your application requires 5300Vrms isolation voltage but can operate with a maximum output current of 100mA (instead of 150mA), the Vishay 4N32 is a suitable substitute. Verify that your circuit design does not exceed 100mA output current requirements.

Q: What is the operating temperature range difference between substitutes?

A: The onsemi 4N32M has a reduced operating temperature range of -40°C ~ 100°C compared to -55°C ~ 100°C for both the original 4N32 and Vishay 4N32. If your application requires operation below -40°C, the 4N32M is not suitable.