FOD260LT Equivalent & Substitute Parts

Part Overview

The FOD260LT is a logic output optoisolator manufactured by onsemi, designed for high-speed digital isolation applications requiring 5000Vrms isolation voltage. This component features open collector output with Schottky clamping, operating at 10Mbps data rate with 25kV/µs common mode transient immunity. The FOD260LT is classified as obsolete, making identification of compatible substitute parts essential for ongoing system support and new design implementations.

Substiute Parts

FOD260LT

onsemiIn Stock: 10427FOD260LT Datasheet

Current PartRFQ

TLP2601(F)

Toshiba Semiconductor and StorageIn Stock: 851TLP2601(F) Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the FOD260LT is determined by the following critical parameters:

Mandatory Compatibility Parameters:

• Single channel configuration (1 input, 0 side 2 inputs)
• Open collector output with Schottky clamping
• DC input type
• Through hole mounting
• 8-DIP package form factor
• Operating temperature range -40°C to 85°C

Performance Parameters Affecting Substitution:

• Isolation voltage (5000Vrms for FOD260LT)
• Common mode transient immunity (25kV/µs for FOD260LT)
• Output current capability (50 mA for FOD260LT)
• Data rate (10Mbps for FOD260LT)
• Supply voltage range (3V ~ 5.5V for FOD260LT)

The TLP2601(F) from Toshiba Semiconductor and Storage shares the core functional architecture but operates at reduced isolation voltage (2500Vrms) and lower common mode transient immunity (1kV/µs). This represents a downgrade in isolation performance and transient immunity specifications.

Parameter Comparison

Engineering Selection Recommendations

FOD260LT Substitution Constraints:

The TLP2601(F) is listed as a substitute part but presents significant specification reductions that must be evaluated against application requirements:

1. Isolation Voltage Reduction: The TLP2601(F) operates at 2500Vrms compared to the FOD260LT's 5000Vrms. Applications requiring the full 5000Vrms isolation specification cannot use this substitute without circuit redesign or additional isolation measures.

2. Common Mode Transient Immunity Reduction: The TLP2601(F) provides 1kV/µs CMTI versus 25kV/µs for the FOD260LT. Systems exposed to high-speed transient events may experience data corruption or signal integrity issues with the reduced CMTI specification.

3. Output Current Capability: The TLP2601(F) is rated for 25 mA output current per channel, half the FOD260LT's 50 mA rating. Load impedance and drive requirements must be verified to ensure adequate current delivery.

4. Supply Voltage Range: The TLP2601(F) requires 4.5V to 5.5V supply voltage, eliminating compatibility with systems operating at 3V. The FOD260LT supports 3V to 5.5V operation.

5. Package Dimensions: Physical pitch differences (10.16mm versus 7.62mm) require PCB layout verification and potential mechanical redesign.

6. Product Status: The TLP2601(F) maintains active production status, ensuring long-term availability and supply chain continuity compared to the obsolete FOD260LT.

Substitution is viable only when application requirements can tolerate reduced isolation voltage, lower CMTI, reduced output current, and narrower supply voltage range specifications.

Frequently Asked Questions (FAQ)

Q: Can the TLP2601(F) directly replace the FOD260LT in existing designs?

A: Direct replacement is not recommended without circuit analysis. The TLP2601(F) has lower isolation voltage (2500Vrms vs 5000Vrms), significantly lower CMTI (1kV/µs vs 25kV/µs), and reduced output current (25 mA vs 50 mA). Physical package dimensions also differ. Substitution requires verification that application requirements can tolerate these specification reductions.

Q: What are the key differences in isolation performance?

A: The FOD260LT provides 5000Vrms isolation voltage with 25kV/µs common mode transient immunity. The TLP2601(F) operates at 2500Vrms isolation with 1kV/µs CMTI. Applications requiring high-voltage isolation or exposure to fast transient events must retain the FOD260LT specification or implement additional circuit protection.

Q: Are there package compatibility issues between these parts?

A: Yes. The FOD260LT uses an 8-DIP package with 0.400" (10.16mm) pitch, while the TLP2601(F) uses an 8-DIP package with 0.300" (7.62mm) pitch. PCB footprints are not interchangeable without layout modification.

Q: What supply voltage range does each part support?

A: The FOD260LT operates from 3V to 5.5V, supporting low-voltage applications. The TLP2601(F) requires 4.5V to 5.5V, eliminating 3V operation capability. Systems designed for 3V supply cannot use the TLP2601(F) as a substitute.

Q: How do output current ratings affect circuit design?

A: The FOD260LT provides 50 mA output current per channel, while the TLP2601(F) provides 25 mA. Load impedance and switching requirements must be recalculated for the reduced current capability. Higher impedance loads or reduced switching speed may be necessary with the TLP2601(F).

Q: Is the TLP2601(F) suitable for high-speed transient environments?

A: The TLP2601(F)'s 1kV/µs CMTI is significantly lower than the FOD260LT's 25kV/µs specification. Applications with fast voltage transitions or high dV/dt conditions should retain the FOD260LT or implement additional filtering and protection circuits.