MOC8111 Equivalent & Substitute Parts

Part Overview

The MOC8111 is a transistor output optoisolator manufactured by onsemi, rated for 5300Vrms isolation voltage in a 6-DIP through-hole package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The MOC8111 provides single-channel DC input isolation with transistor output configuration, suitable for applications requiring high-voltage galvanic isolation.

Key Parameters

Parameter	MOC8111 (onsemi)
Voltage - Isolation	5300Vrms
Number of Channels	1
Current Transfer Ratio (Min)	20% @ 10mA
Output Type	Transistor
Voltage - Output (Max)	70V
Vce Saturation (Max)	400mV
Operating Temperature	-55°C ~ 100°C
Package / Case	6-DIP (0.300", 7.62mm)
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitution eligibility for the MOC8111 is determined by the following critical parameters:

Isolation Voltage: Minimum 5300Vrms required to maintain equivalent isolation performance
Output Configuration: Transistor output type (with or without base connection acceptable)
Package Compatibility: 6-DIP through-hole form factor with 0.300" (7.62mm) pitch
Single Channel: One isolated channel required
DC Input Type: Direct current input interface
Operating Temperature Range: Must support -55°C to 100°C minimum

Based on these criteria, the following parts are evaluated:

Direct Equivalent (Identical Isolation Voltage):

MOC8111 (Fairchild Semiconductor) - Same part number, different manufacturer source

Partial Substitutes (Lower Isolation Voltage):

CNY17F1M (Fairchild Semiconductor) - 4170Vrms isolation
4N25-000E (Broadcom Limited) - 2500Vrms isolation

Parameter Comparison

Parameter	MOC8111 (onsemi)	MOC8111 (Fairchild)	CNY17F1M	4N25-000E
Manufacturer	onsemi	Fairchild Semiconductor	Fairchild Semiconductor	Broadcom Limited
Voltage - Isolation	5300Vrms	5300Vrms	4170Vrms	2500Vrms
Current Transfer Ratio (Min)	20% @ 10mA	20% @ 10mA	40% @ 10mA	20% @ 10mA
Output Type	Transistor	Transistor	Transistor	Transistor with Base
Voltage - Output (Max)	70V	70V	70V	30V
Vce Saturation (Max)	400mV	400mV	400mV	500mV
Operating Temperature	-55°C ~ 100°C	-55°C ~ 100°C	-40°C ~ 100°C	-55°C ~ 100°C
Package / Case	6-DIP (0.300", 7.62mm)	6-DIP (0.300", 7.62mm)	6-DIP (0.300", 7.62mm)	6-DIP (0.300", 7.62mm)
Product Status	Obsolete	Obsolete	Active	Active

Engineering Selection Recommendations

MOC8111 (Fairchild Semiconductor) is the direct equivalent source alternative. Both onsemi and Fairchild versions share identical electrical specifications (5300Vrms isolation, 20% CTR minimum, 70V output maximum, 400mV saturation). Both are classified as obsolete; however, Fairchild inventory is available in tube packaging. This part maintains full compatibility with original MOC8111 designs without parameter derating.

CNY17F1M provides an active-status alternative with enhanced current transfer ratio (40% minimum) and faster switching characteristics. The isolation voltage is reduced to 4170Vrms, which represents a 21% reduction from the original specification. This part is suitable only for applications where the lower isolation voltage meets system requirements. Operating temperature range is limited to -40°C minimum, excluding low-temperature operation below this threshold.

4N25-000E is an active-status option with the lowest isolation voltage (2500Vrms, 53% reduction from original). Output voltage maximum is also reduced to 30V compared to 70V on the original part. The transistor output includes base connection, providing additional design flexibility. This part is suitable only for low-voltage isolation applications and does not meet the isolation requirements of designs specified for 5300Vrms performance.

Frequently Asked Questions (FAQ)

Q: Can CNY17F1M replace MOC8111 in all applications?

A: No. CNY17F1M has 4170Vrms isolation versus MOC8111's 5300Vrms. Substitution is valid only if your application isolation requirement is 4170Vrms or lower. Additionally, CNY17F1M operating temperature minimum is -40°C, excluding applications requiring -55°C operation.

Q: Is 4N25-000E a suitable replacement for MOC8111?

A: 4N25-000E is not a direct replacement. It provides only 2500Vrms isolation (47% lower than MOC8111) and 30V maximum output voltage (57% lower than MOC8111). Use this part only if your design specifications allow these reduced ratings.

Q: What is the difference between MOC8111 from onsemi and MOC8111 from Fairchild?

A: Both versions are electrically identical with 5300Vrms isolation, 20% minimum CTR, and identical thermal/timing characteristics. The primary difference is manufacturer source and packaging format (onsemi listed as standard packaging; Fairchild available in tube). Both are obsolete status.

Q: Are all substitute parts compatible with 6-DIP PCB footprints?

A: Yes. All listed parts use 6-DIP (0.300", 7.62mm) through-hole package format and are mechanically compatible with standard 6-DIP footprints.

Q: Which substitute part has the best current transfer ratio?

A: CNY17F1M offers 40% minimum CTR at 10mA, compared to 20% minimum on MOC8111, 4N25-000E, and the Fairchild MOC8111. Higher CTR provides improved switching efficiency and reduced input current requirements.

Q: Can I use these parts interchangeably in production?

A: No. Each part has distinct electrical specifications. Substitution requires design verification that the target part's isolation voltage, output voltage rating, and operating temperature range meet or exceed your application requirements.

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