EL357NF(TA)-VG Optoisolator Equivalent & Substitute Parts

Part Overview

The EL357NF(TA)-VG is a single-channel optoisolator with transistor output manufactured by Everlight Electronics Co Ltd. This component provides 3750Vrms isolation voltage and is designed for DC input applications requiring galvanic isolation in surface mount configurations. The part is Active status and RoHS3 compliant with unlimited moisture sensitivity rating (MSL 1).

Substitute parts are identified when equivalent electrical performance and mechanical compatibility can be maintained across isolation voltage, output current capacity, switching characteristics, and package form factors. Alternative sources and packaging options (Tube, Tape & Reel, Cut Tape) are available from onsemi and Broadcom Limited manufacturers.

Key Parameters

Parameter	Value	Unit
Isolation Voltage	3750	Vrms
Number of Channels	1	—
Output Type	Transistor	—
Current Transfer Ratio (Min)	150	% @ 5mA
Current Transfer Ratio (Max)	300	% @ 5mA
Maximum Output Voltage	80	V
Output Current per Channel	50	mA
Vce Saturation (Max)	200	mV
Forward Voltage (Typ)	1.2	V
Rise / Fall Time	3 / 4	µs
Operating Temperature Range	-55 to 110	°C
Package Type	4-SMD, Gull Wing	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence in the following critical parameters:

Primary Equivalence Criteria:

Isolation voltage: 3750Vrms (mandatory match)
Output type: Transistor (mandatory match)
Number of channels: 1 (mandatory match)
Input type: DC (mandatory match)
Maximum output voltage: 80V (mandatory match)
Package configuration: 4-SMD, Gull Wing or compatible surface mount form factor

Secondary Compatibility Parameters:

Current Transfer Ratio range must encompass or overlap the 150–300% specification
Output current capacity must be ≥50mA per channel
Vce saturation must be ≤200mV or within acceptable switching loss tolerance
Forward voltage must be compatible with 1.2V nominal specification
Operating temperature range must cover or exceed -55°C to 110°C
RoHS3 compliance and MSL 1 rating required

Packaging Variants: Substitute parts are available in Tube, Tape & Reel (TR), and Cut Tape (CT) & Digi-Reel® packaging. These represent the same electrical component in different distribution formats and do not affect functional equivalence.

Parameter Comparison

Part Number	Manufacturer	Isolation (Vrms)	CTR Min (% @ 5mA)	CTR Max (% @ 5mA)	Vce Sat Max (mV)	Output Current (mA)	Vf Typ (V)	Temp Range (°C)	Package	RoHS
EL357NF(TA)-VG	Everlight	3750	150	300	200	50	1.2	-55 to 110	4-SOP (2.54mm)	ROHS3
FODM121	onsemi	3750	50	600	400	80	1.3	-40 to 110	4-SMD	ROHS3
FODM121AR2	onsemi	3750	100	300	400	80	1.3	-40 to 110	4-SMD	ROHS3
FODM121B	onsemi	3750	50	150	400	80	1.3	-40 to 110	4-SMD	ROHS3
FODM121C	onsemi	3750	100	200	400	80	1.3	-40 to 110	4-SMD	ROHS3
FODM121CR2	onsemi	3750	100	200	400	80	1.3	-40 to 110	4-SMD	ROHS3
FODM121R2	onsemi	3750	50	600	400	80	1.3	-40 to 110	4-SMD	ROHS3
FODM124R2	onsemi	3750	100	1200	400	80	1.3	-40 to 110	4-SMD	ROHS3
HCPL-181-000E	Broadcom	3750	50	600	200	50	1.2	-55 to 100	4-SOIC (5.30mm)	ROHS3
HCPL-181-00AE	Broadcom	3750	80	160	200	50	1.2	-55 to 100	4-Mini-Flat	ROHS3
HCPL-181-00BE	Broadcom	3750	130	260	200	50	1.2	-55 to 100	4-Mini-Flat	ROHS3

Engineering Selection Recommendations

Closest Electrical Equivalents:

HCPL-181-00BE (Broadcom Limited) provides the most direct substitution for EL357NF(TA)-VG. Both components share identical isolation voltage (3750Vrms), matching Vce saturation (200mV), forward voltage (1.2V), and output current (50mA). Current Transfer Ratio specifications (130–260% vs. 150–300%) overlap within acceptable operating margins. Operating temperature range differs only at the upper limit (100°C vs. 110°C). Package form is 4-Mini-Flat surface mount, compatible with standard PCB assembly processes.

HCPL-181-000E (Broadcom Limited) offers equivalent electrical performance with broader Current Transfer Ratio range (50–600%). Vce saturation and forward voltage match the main part. Output current capacity is identical at 50mA. Operating temperature maximum is 100°C. Package is 4-SOIC (0.209", 5.30mm Width).

onsemi FODM Series Considerations:

FODM121AR2, FODM121C, and FODM121CR2 provide 3750Vrms isolation with Current Transfer Ratio ranges that encompass the main part specification. Output current capacity is higher at 80mA. Vce saturation is elevated to 400mV, resulting in increased switching losses. Forward voltage is 1.3V nominal. Operating temperature range is -40°C to 110°C, with lower minimum temperature limit. These parts are suitable for applications where higher output current and broader CTR tolerance are acceptable trade-offs.

FODM124R2 (onsemi) features exceptionally high Current Transfer Ratio (100–1200% @ 1mA) and is specified at 1mA input current rather than 5mA. This part is applicable only to circuits designed for low-input-current operation.

Compliance and Certification:

All listed substitute parts maintain RoHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, matching the main part specifications. REACH status is unaffected for onsemi and Broadcom parts. ECCN and HTSUS classifications are identical across all components.

Packaging and Inventory:

Substitute parts are available in multiple packaging formats (Tube, Tape & Reel, Cut Tape & Digi-Reel®). Selection should be based on procurement volume and assembly process requirements. Inventory availability varies by part number and packaging variant.

Frequently Asked Questions (FAQ)

Q: Can FODM121 series parts directly replace EL357NF(TA)-VG in existing designs?

A: FODM121 variants are electrically compatible at the 3750Vrms isolation level and single-channel transistor output configuration. However, Vce saturation is 400mV versus 200mV for the main part, resulting in higher power dissipation in the output stage. Circuit designs with tight thermal budgets or low-impedance loads must account for this difference. Output current capacity is higher (80mA vs. 50mA), which is advantageous. Operating temperature minimum is -40°C instead of -55°C.

Q: What is the difference between FODM121, FODM121AR2, FODM121B, FODM121C, and FODM121CR2?

A: These are variants of the same base component (FODM121) with different Current Transfer Ratio specifications and packaging formats. FODM121 and FODM121R2 specify 50–600% CTR. FODM121AR2 specifies 100–300% CTR. FODM121B specifies 50–150% CTR. FODM121C and FODM121CR2 specify 100–200% CTR. Packaging differences are Tube (standard), Tape & Reel (TR), and Cut Tape (CT) & Digi-Reel®. Electrical performance is identical except for CTR range.

Q: How do Broadcom HCPL-181 parts compare to Everlight EL357NF(TA)-VG?

A: HCPL-181-00BE and HCPL-181-000E maintain identical isolation voltage, Vce saturation (200mV), forward voltage (1.2V), and output current (50mA) specifications. Current Transfer Ratio ranges differ slightly but overlap. Operating temperature maximum is 100°C versus 110°C for the main part. Package form is 4-Mini-Flat or 4-SOIC, both surface mount configurations. These parts are direct functional equivalents with minimal design impact.

Q: What does Current Transfer Ratio (CTR) represent, and why does it vary across substitute parts?

A: Current Transfer Ratio is the ratio of output collector current to input LED current, expressed as a percentage. It indicates the efficiency of optical coupling and determines the input current required to achieve a specified output current. Higher CTR means less input current is needed. Variations across substitute parts reflect different LED and phototransistor designs. The main part specifies 150–300% CTR @ 5mA, while substitutes range from 50–1200% depending on the variant. Circuit designs must account for the CTR range of the selected part to ensure proper switching behavior.

Q: Can I use FODM124R2 as a substitute for EL357NF(TA)-VG?

A: FODM124R2 is electrically compatible at the isolation voltage and output type level. However, it is specified with 100–1200% CTR @ 1mA input current, whereas the main part uses 5mA input current. This part is designed for low-input-current applications and requires circuit redesign to operate correctly. Use FODM124R2 only if your application is specifically designed for 1mA input current operation.

Q: What are the package differences between 4-SOP, 4-SMD, 4-Mini-Flat, and 4-SOIC?

A: All four package types are surface mount configurations with four leads. 4-SOP (Small Outline Package) and 4-SMD (Surface Mount Device) are functionally equivalent gull-wing lead configurations. 4-Mini-Flat is a compact surface mount package with flat leads. 4-SOIC (Small Outline Integrated Circuit) is a standard 0.209" (5.30mm) width package. All are compatible with standard PCB assembly equipment. Physical dimensions differ, so PCB footprint design must match the selected part's package specification.

Q: Does operating temperature range affect substitution suitability?

A: Operating temperature range defines the environmental conditions under which the component functions within specification. EL357NF(TA)-VG operates from -55°C to 110°C. HCPL-181 series parts operate from -55°C to 100°C, with a 10°C lower maximum. FODM121 series parts operate from -40°C to 110°C, with a 15°C higher minimum. If your application requires operation below -40°C or above 100°C, part selection must match those requirements. For standard industrial temperature ranges (-40°C to 85°C), all listed substitutes are suitable.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts carry RoHS3 compliance certification, matching the main part. Moisture Sensitivity Level (MSL) is 1 (Unlimited) for all components, indicating no special moisture handling requirements during storage or assembly.

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