VO4258H Optoisolator Equivalent & Substitute Parts

Part Overview

The VO4258H is a high-voltage optoisolator with triac output manufactured by Vishay Semiconductor Opto Division. This component provides galvanic isolation up to 5300Vrms with a single-channel triac output configuration in a 6-DIP through-hole package. The device is actively produced and widely used in industrial control, power management, and AC switching applications requiring robust isolation and high dV/dt performance.

Equivalent and substitute parts are identified when component availability is limited, supply chain disruptions occur, or design flexibility is required while maintaining functional compatibility within specified electrical and mechanical parameters.

Substiute Parts

VO4258H

Vishay Semiconductor Opto DivisionIn Stock: 1420VO4258H Datasheet

Current PartRFQ

FOD4208

onsemiIn Stock: 2386FOD4208 Datasheet

MFR RecommendedRFQ

FOD4218

onsemiIn Stock: 1215FOD4218 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the VO4258H are qualified based on the following critical parameters that determine functional compatibility:

Mandatory Compatibility Criteria:

• Output Type: Triac
• Number of Channels: 1
• Package / Case: 6-DIP (0.300", 7.62mm)
• Mounting Type: Through Hole
• Operating Temperature Range: -55°C ~ 100°C (minimum)
• Voltage - Isolation: 5000Vrms or higher
• Voltage - Off State: 800 V or higher
• Current - On State (It (RMS)): 300 mA or higher

Identified Substitutes:

• FOD4208 (onsemi)
• FOD4218 (onsemi)

Both substitutes meet the mandatory compatibility criteria. The FOD4208 and FOD4218 are onsemi-manufactured optoisolators with triac output in 6-DIP packages, identical operating temperature range, and equivalent isolation voltage specifications (5000Vrms). Both devices maintain the required off-state voltage and on-state current ratings necessary for direct functional replacement in VO4258H applications.

Parameter Comparison

Engineering Selection Recommendations

VO4258H (Primary Component) The VO4258H remains the primary choice when available. It offers the highest isolation voltage specification (5300Vrms) and maximum DC forward current rating (60 mA), providing design margin in high-voltage isolation applications.

FOD4208 (Direct Substitute) The FOD4208 is suitable for applications where the VO4258H is unavailable. It meets all mandatory compatibility criteria with equivalent isolation voltage (5000Vrms), off-state voltage (800 V), and on-state current (300 mA maximum). The FOD4208 features superior static dV/dt performance (10kV/µs versus 5kV/µs) and is ROHS3 compliant with active product status. Regulatory approvals include cUL, FIMKO, and UL certifications.

FOD4218 (Alternative Substitute) The FOD4218 provides an alternative substitute option with identical electrical specifications to the FOD4208, with the exception of a lower LED trigger current maximum (1.3mA versus 2mA). This lower trigger current may reduce input drive requirements in certain circuit designs. The FOD4218 maintains all other critical parameters and regulatory compliance equivalent to the FOD4208.

Selection Basis All three components are actively produced, ROHS3 compliant, and maintain the required operating temperature range. The FOD4208 and FOD4218 are functionally compatible substitutes based on package type, isolation voltage, off-state voltage, and on-state current specifications. Regulatory certifications differ between manufacturers but remain valid for industrial control and power management applications.

Frequently Asked Questions (FAQ)

Q: Can FOD4208 or FOD4218 be used as direct pin-for-pin replacements for VO4258H?

A: Yes. Both FOD4208 and FOD4218 are packaged in 6-DIP (0.300", 7.62mm) through-hole configuration identical to the VO4258H. Pin assignments and functional operation are compatible for direct board-level substitution.

Q: What is the difference between FOD4208 and FOD4218?

A: The primary difference is the LED trigger current maximum specification. FOD4218 has a maximum LED trigger current of 1.3mA compared to FOD4208 at 2mA. Both devices share identical isolation voltage (5000Vrms), off-state voltage (800 V), on-state current (300 mA maximum), and operating temperature range (-55°C ~ 100°C). The lower trigger current of FOD4218 may reduce input drive power requirements.

Q: Is the isolation voltage difference between VO4258H (5300Vrms) and FOD4208/FOD4218 (5000Vrms) significant?

A: The VO4258H provides 300Vrms higher isolation voltage specification. For applications requiring the full 5300Vrms isolation margin, the VO4258H is the appropriate choice. For applications operating within 5000Vrms isolation requirements, FOD4208 and FOD4218 are functionally equivalent.

Q: Are all three components RoHS compliant?

A: Yes. VO4258H, FOD4208, and FOD4218 are all ROHS3 compliant and REACH unaffected.

Q: What are the regulatory certifications for each component?

A: VO4258H carries BSI, cUR, FIMKO, and UR approvals. FOD4208 and FOD4218 carry cUL, FIMKO, and UL approvals. Both certification sets are valid for industrial control and power management applications.

Q: Can I use FOD4208 or FOD4218 in a design originally specified for VO4258H?

A: Substitution is permissible when the application isolation voltage requirement does not exceed 5000Vrms and all other electrical parameters (off-state voltage, on-state current, operating temperature) are met. Verify circuit design margins and regulatory compliance requirements for your specific application before substitution.