MOC8108S Equivalent & Substitute Parts

Part Overview

The MOC8108S is an optoisolator with transistor output manufactured by onsemi, featuring 5300Vrms isolation voltage and 1 channel configuration in 6-SMD surface mount packaging. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement continuity. The MOC8108S serves applications requiring high-voltage isolation with DC input and transistor output characteristics.

Substiute Parts

MOC8108S

onsemiIn Stock: 858MOC8108S Datasheet

Current PartRFQ

CNY17F4SM

Fairchild SemiconductorIn Stock: 2269CNY17F4SM Datasheet

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MOC8108SM

Isocom Components 2004 LTDIn Stock: 1172MOC8108SM Datasheet

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MOC8108SMT&R

Isocom Components 2004 LTDIn Stock: 785MOC8108SMT&R Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MOC8108S is determined by the following critical parameters:

Primary Matching Criteria:

• Number of Channels: 1
• Output Type: Transistor
• Package / Case: 6-SMD, Gull Wing
• Mounting Type: Surface Mount
• Input Type: DC

Electrical Performance Criteria:

• Voltage - Isolation: 5300Vrms or higher
• Voltage - Output (Max): 70V or higher
• Vce Saturation (Max): 400mV or lower
• Operating Temperature Range: Must encompass -55°C to 100°C or be compatible with application requirements

Acceptable Variance:

• Current Transfer Ratio: Minimum 250% @ 10mA acceptable; higher values permissible
• Turn On / Turn Off Time: Variations acceptable if within application timing requirements
• Current - Output / Channel: 50mA or higher acceptable

The substitute parts listed below meet these criteria within the specified electrical and mechanical parameters.

Parameter Comparison

Engineering Selection Recommendations

MOC8108SM and MOC8108SMT&R (Isocom Components 2004 LTD): These parts provide the closest electrical equivalence to the MOC8108S, maintaining identical isolation voltage (5300Vrms), current transfer ratio specifications (250-600% @ 10mA), and operating temperature range (-55°C ~ 100°C). Both are active products with RoHS3 compliance and REACH unaffected status. The primary difference is packaging format: MOC8108SM is supplied in Tube, while MOC8108SMT&R is supplied in Tape & Reel. Timing characteristics show longer turn-on/turn-off times (7.5µs, 5.7µs) compared to the original part, which must be evaluated against application requirements. Current - Output / Channel specification is not provided for these variants.

CNY17F4SM (Fairchild Semiconductor): This part meets the core functional requirements with matching output voltage (70V), saturation voltage (400mV), and identical turn-on/turn-off timing (2µs, 3µs). However, the isolation voltage is reduced to 4170Vrms, representing a 21% decrease from the MOC8108S specification. The current transfer ratio minimum is also lower at 160% @ 10mA. The operating temperature range is limited to -40°C ~ 100°C, excluding the lower temperature extreme of the original specification. This part is suitable only for applications where the reduced isolation voltage and lower temperature minimum are acceptable. Supplied in Bulk packaging.

Product Status Consideration: MOC8108SM and MOC8108SMT&R are active products, ensuring long-term availability and supply chain stability. CNY17F4SM is also active. The obsolete status of MOC8108S necessitates transition to one of these active alternatives.

Frequently Asked Questions (FAQ)

Q: Can CNY17F4SM replace MOC8108S in all applications? A: No. CNY17F4SM has reduced isolation voltage (4170Vrms vs. 5300Vrms) and a narrower operating temperature range (-40°C to 100°C vs. -55°C to 100°C). Applications requiring the full 5300Vrms isolation or operation below -40°C must use MOC8108SM or MOC8108SMT&R.

Q: What is the difference between MOC8108SM and MOC8108SMT&R? A: Both parts are electrically identical. The difference is packaging: MOC8108SM is supplied in Tube format, while MOC8108SMT&R is supplied in Tape & Reel format. Selection depends on assembly process requirements and volume.

Q: Are timing differences between MOC8108S and MOC8108SM significant? A: MOC8108SM has longer turn-on/turn-off times (7.5µs, 5.7µs) compared to MOC8108S (2µs, 3µs). Applications with strict timing requirements must evaluate whether this 2.75x to 1.9x increase is acceptable.

Q: Do all substitute parts have the same package footprint? A: Yes. All listed substitutes use 6-SMD, Gull Wing surface mount packaging, ensuring mechanical compatibility with existing PCB designs.

Q: What compliance certifications apply to these substitutes? A: MOC8108SM and MOC8108SMT&R are RoHS3 compliant and REACH unaffected. CNY17F4SM compliance information is not provided in the available data. All parts carry ECCN EAR99 and HTSUS 8541.49.8000 classifications.

Q: Which substitute offers the best long-term availability? A: MOC8108SM and MOC8108SMT&R are manufactured by Isocom Components 2004 LTD and are active products with current inventory. CNY17F4SM is also active. All three are preferable to the obsolete MOC8108S for new designs.