FODM121CV Optoisolator Equivalent & Substitute Parts

Part Overview

The FODM121CV is a 3750Vrms optoisolator with transistor output manufactured by onsemi in a 4-SMD gull wing package. This component is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The FODM121CV provides single-channel isolation suitable for applications requiring high-voltage galvanic isolation with DC input and transistor output configuration.

Key Parameters

Parameter	FODM121CV
Manufacturer	onsemi
Voltage - Isolation	3750Vrms
Number of Channels	1
Output Type	Transistor
Input Type	DC
Voltage - Output (Max)	80V
Current - Output / Channel	80mA
Current Transfer Ratio (Min)	100% @ 5mA
Current Transfer Ratio (Max)	200% @ 5mA
Vce Saturation (Max)	400mV
Operating Temperature	-40°C ~ 110°C
Mounting Type	Surface Mount
Package / Case	4-SMD, Gull Wing
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the FODM121CV is determined by the following critical parameters that must remain compatible:

Mandatory Matching Parameters:

Voltage - Isolation: 3750Vrms (all substitutes maintain this specification)
Number of Channels: 1 (single-channel configuration)
Output Type: Transistor (all substitutes provide transistor output)
Input Type: DC (all substitutes accept DC input)
Voltage - Output (Max): 80V (all substitutes support this maximum output voltage)
Mounting Type: Surface Mount (all substitutes are surface mount)
Moisture Sensitivity Level (MSL): 1 (Unlimited) (all substitutes match this rating)

Flexible Parameters (within acceptable ranges):

Current - Output / Channel: FODM121CV provides 80mA; substitutes provide 50mA (lower but acceptable for most applications)
Current Transfer Ratio: FODM121CV range 100-200% @ 5mA; substitutes range from 50-600% @ 5mA depending on variant
Vce Saturation: FODM121CV 400mV (Max); substitutes 200mV (Max) (improved performance)
Operating Temperature: FODM121CV -40°C ~ 110°C; substitutes range -55°C ~ 110°C (extended or equivalent range)
Package / Case: 4-SMD Gull Wing (primary), 4-SOP, 4-SOIC, 4-Mini-Flat (package variants available)

Substitutes are grouped by package type and current transfer ratio specification to facilitate selection based on circuit requirements.

Parameter Comparison

Part Number	Manufacturer	Voltage - Isolation	Current Transfer Ratio (Min)	Current Transfer Ratio (Max)	Voltage - Output (Max)	Current - Output / Channel	Vce Saturation (Max)	Operating Temperature	Package / Case	Product Status
FODM121CV	onsemi	3750Vrms	100% @ 5mA	200% @ 5mA	80V	80mA	400mV	-40°C ~ 110°C	4-SMD, Gull Wing	Obsolete
EL357ND(TA)-G	Everlight Electronics Co Ltd	3750Vrms	300% @ 5mA	600% @ 5mA	80V	50mA	200mV	-55°C ~ 110°C	4-SMD, Gull Wing	Active
HCPL-181-000E	Broadcom Limited	3750Vrms	50% @ 5mA	600% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SOIC (0.209", 5.30mm Width)	Active
HCPL-181-00AE	Broadcom Limited	3750Vrms	80% @ 5mA	160% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SMD, Gull Wing	Active
HCPL-181-00BE	Broadcom Limited	3750Vrms	130% @ 5mA	260% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SMD, Gull Wing	Active
HCPL-181-00CE	Broadcom Limited	3750Vrms	200% @ 5mA	400% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SMD, Gull Wing	Active
HCPL-181-00DE	Broadcom Limited	3750Vrms	300% @ 5mA	600% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SMD, Gull Wing	Active
HCPL-181-06BE	Broadcom Limited	3750Vrms	130% @ 5mA	260% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SMD, Gull Wing	Active
HCPL-181-06DE	Broadcom Limited	3750Vrms	300% @ 5mA	600% @ 5mA	80V	50mA	200mV	-55°C ~ 100°C	4-SMD, Gull Wing	Active
LTV-356T	Lite-On Inc.	3750Vrms	50% @ 5mA	600% @ 5mA	80V	50mA	200mV	-55°C ~ 110°C	4-SMD, Gull Wing	Active
PC357N4J000F	SHARP/Socle Technology	3750Vrms	300% @ 5mA	600% @ 5mA	80V	50mA	200mV	-30°C ~ 100°C	4-SMD, Gull Wing	Active

Engineering Selection Recommendations

All listed substitute parts maintain the critical 3750Vrms isolation voltage and single-channel transistor output configuration required for FODM121CV replacement. Selection should be based on the following criteria:

For Direct Package Compatibility (4-SMD Gull Wing): HCPL-181-00BE, HCPL-181-00CE, HCPL-181-00DE, HCPL-181-06BE, HCPL-181-06DE, EL357ND(TA)-G, LTV-356T, and PC357N4J000F all provide 4-SMD gull wing packaging matching the original footprint.

For Current Transfer Ratio Matching: HCPL-181-00CE provides 200-400% @ 5mA, closest to the FODM121CV specification of 100-200% @ 5mA. HCPL-181-00BE and HCPL-181-06BE provide 130-260% @ 5mA, also within acceptable range.

For Extended Temperature Range: EL357ND(TA)-G and LTV-356T support -55°C ~ 110°C, exceeding the FODM121CV range of -40°C ~ 110°C.

For Active Product Status: All substitute parts listed are active products with ongoing manufacturer support and availability, eliminating obsolescence risk.

For Compliance: All substitute parts carry ROHS3 compliance and REACH Unaffected status where specified, ensuring regulatory alignment.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with lower current output (50mA vs. 80mA)? A: Yes, if your circuit design requires maximum 50mA output current. The FODM121CV's 80mA capability is not a mandatory requirement for all applications. Verify your specific circuit current requirements before selection.

Q: What is the significance of Current Transfer Ratio (CTR) variations among substitutes? A: Current Transfer Ratio determines the output current relative to input current. The FODM121CV specifies 100-200% @ 5mA. Substitutes with higher CTR (300-600%) provide greater output current for the same input, while lower CTR (50-80%) requires higher input current for equivalent output. Select based on your input drive capability and output current requirements.

Q: Are package variants (4-SOIC, 4-SOP, 4-Mini-Flat) interchangeable with the original 4-SMD gull wing? A: No. Package variants require different PCB footprints and cannot be used as direct drop-in replacements. HCPL-181-000E (4-SOIC) and EL357ND(TA)-G (4-SOP) require PCB redesign. For direct footprint compatibility, select parts specified as 4-SMD gull wing.

Q: Does lower Vce Saturation (200mV vs. 400mV) affect circuit operation? A: Lower Vce Saturation improves switching performance and reduces power dissipation in the output transistor. This is a beneficial characteristic and does not create compatibility issues.

Q: Which substitute offers the best overall compatibility with FODM121CV? A: HCPL-181-00CE provides the closest Current Transfer Ratio match (200-400% vs. 100-200%), maintains 4-SMD gull wing packaging, and is an active Broadcom product with extensive availability and ROHS3 compliance.

Q: Can I use substitutes with extended temperature ranges in applications not requiring them? A: Yes. Extended temperature range capability does not restrict use in narrower temperature applications. Parts rated -55°C ~ 110°C operate normally within -40°C ~ 110°C ranges.

Q: What is Moisture Sensitivity Level (MSL) 1? A: MSL 1 indicates unlimited shelf life without moisture exposure controls. All listed parts and the original FODM121CV share this rating, ensuring equivalent handling and storage requirements.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message