MOC8108W Equivalent & Substitute Parts

Part Overview

The MOC8108W is an optoisolator with transistor output, rated for 5300Vrms isolation voltage. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing system maintenance and new design implementations. The MOC8108W provides galvanic isolation in applications requiring high voltage separation with single-channel transistor output configuration.

Substiute Parts

MOC8108W

onsemiIn Stock: 5308MOC8108W Datasheet

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MOC8108G

Isocom Components 2004 LTDIn Stock: 1083MOC8108G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the MOC8108W is determined by the following critical parameters:

• Voltage - Isolation: 5300Vrms (must match exactly)
• Number of Channels: 1 (single channel configuration)
• Output Type: Transistor (not photodiode or other output types)
• Package / Case: 6-DIP (0.400", 10.16mm) (physical and electrical compatibility)
• Current Transfer Ratio range: 250% to 600% @ 10mA (functional performance window)
• Vce Saturation (Max): 400mV (output saturation characteristic)
• Operating Temperature: -55°C ~ 100°C (thermal operating range)

The MOC8108G qualifies as a direct substitute based on matching all critical isolation, channel, output type, and package specifications. Differences in switching speed characteristics (Turn On/Turn Off Time and Rise/Fall Time) do not disqualify substitution when the application does not impose stricter timing requirements than the substitute part's specifications.

Parameter Comparison

Engineering Selection Recommendations

The MOC8108G (Isocom Components 2004 LTD) is a qualified substitute for the obsolete MOC8108W. Selection should be based on the following factors:

Product Status: The MOC8108G carries Active product status, ensuring continued availability and supply chain reliability compared to the Obsolete MOC8108W.

Compliance: The MOC8108G is ROHS3 Compliant, meeting current environmental and regulatory requirements for electronic components in regulated markets.

Electrical Compatibility: Both parts maintain identical isolation voltage (5300Vrms), current transfer ratio specifications (250%-600% @ 10mA), output voltage rating (70V), and saturation characteristics (400mV max). These parameters ensure functional equivalence in isolation and switching applications.

Timing Characteristics: The MOC8108G exhibits slower switching performance (Turn On/Turn Off Time: 7.5µs, 5.7µs versus 2µs, 3µs; Rise/Fall Time: 3.2µs, 4.7µs versus 1µs, 2µs). Applications with timing-critical requirements must verify that the substitute part's switching speed remains acceptable for the intended circuit function.

Input Current: The MOC8108G supports maximum DC forward current of 60mA compared to 100mA for the MOC8108W. Input circuit design must accommodate this reduced current rating.

Frequently Asked Questions (FAQ)

Q: Can MOC8108G directly replace MOC8108W in existing designs?

A: Yes, for applications where the slower switching speed of the MOC8108G (7.5µs turn-on, 5.7µs turn-off) is acceptable. The isolation voltage, output voltage rating, current transfer ratio, and saturation voltage are identical. Verify that your circuit does not impose stricter timing requirements than the MOC8108G specifications.

Q: What is the primary difference between MOC8108W and MOC8108G?

A: The MOC8108G has slower switching characteristics and a reduced maximum DC forward input current (60mA versus 100mA). The MOC8108G is also currently in active production, whereas the MOC8108W is obsolete.

Q: Are there package compatibility issues when substituting MOC8108G for MOC8108W?

A: No. Both parts use identical 6-DIP (0.400", 10.16mm) through-hole packaging. PCB layouts and socket designs require no modification.

Q: Does the MOC8108G meet current regulatory requirements?

A: Yes. The MOC8108G is ROHS3 Compliant, meeting current environmental regulations for electronic components in regulated markets.

Q: What applications are affected by the slower switching speed of MOC8108G?

A: Applications with switching frequencies above approximately 100 kHz or circuits requiring sub-microsecond response times may be affected. Standard isolation and switching applications operating at lower frequencies are not impacted.

Q: Is the MOC8108G suitable for high-temperature applications?

A: Yes. The MOC8108G maintains the same operating temperature range as the MOC8108W: -55°C to 100°C.