EL357NB(TA)-VG Equivalent & Substitute Parts

Part Overview

The EL357NB(TA)-VG is an optoisolator with transistor output manufactured by Everlight Electronics Co Ltd. This component provides 3750Vrms isolation voltage in a 4-SOP surface mount package, designed for DC input applications requiring galvanic isolation. The part is active and in production status with 925 units currently in stock.

Substitute parts are identified based on matching electrical specifications including isolation voltage, output type, channel configuration, and mechanical compatibility. Alternative models may be required due to inventory availability, packaging preferences, or specific performance parameter requirements within the allowed operational ranges.

Key Parameters

Parameter	Value
Isolation Voltage	3750Vrms
Number of Channels	1
Output Type	Transistor
Input Type	DC
Maximum Output Voltage	80V
Maximum Output Current per Channel	50mA
Mounting Type	Surface Mount
Package Type	4-SMD, Gull Wing
Operating Temperature Range	-55°C to 110°C
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following core parameters:

Mandatory Matching Criteria:

Isolation voltage: 3750Vrms
Output type: Transistor
Number of channels: 1
Input type: DC
Maximum output voltage: 80V
Mounting type: Surface Mount
RoHS compliance: ROHS3 Compliant
Moisture sensitivity level: 1 (Unlimited)

Allowable Parameter Variations:

Current Transfer Ratio (CTR): Substitute parts may have different minimum and maximum CTR ranges at specified test currents (5mA or 1mA)
Maximum output current per channel: Substitute parts may exceed 50mA (up to 80mA)
Vce saturation: Substitute parts may have different maximum values (200mV to 400mV)
Forward voltage (Vf): Substitute parts may have different typical values (1.2V to 1.3V)
Rise/Fall time: Substitute parts may have different timing specifications (3µs to 4µs range)
Operating temperature range: Substitute parts may have narrower ranges (-40°C to 110°C acceptable)
Package case designation: Substitute parts may use different SMD package variants (4-SMD, 4-SOIC, 4-Mini-Flat)

Substitute parts from onsemi (FODM series) and Broadcom Limited (HCPL-181 series) meet these criteria with variations in performance characteristics within acceptable engineering tolerances.

Parameter Comparison

Parameter	EL357NB(TA)-VG	FODM121	FODM121AR2	FODM121B	FODM121C	FODM121CR2	FODM121R2	FODM124R2	HCPL-181-000E	HCPL-181-00AE	HCPL-181-00BE
Manufacturer	Everlight Electronics	onsemi	onsemi	onsemi	onsemi	onsemi	onsemi	onsemi	Broadcom Limited	Broadcom Limited	Broadcom Limited
Isolation Voltage	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms
Number of Channels	1	1	1	1	1	1	1	1	1	1	1
Output Type	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor
Input Type	DC	DC	DC	DC	DC	DC	DC	DC	DC	DC	DC
CTR Min @ Test Current	130% @ 5mA	50% @ 5mA	100% @ 5mA	50% @ 5mA	100% @ 5mA	100% @ 5mA	50% @ 5mA	100% @ 1mA	50% @ 5mA	80% @ 5mA	130% @ 5mA
CTR Max @ Test Current	260% @ 5mA	600% @ 5mA	300% @ 5mA	150% @ 5mA	200% @ 5mA	200% @ 5mA	600% @ 5mA	1200% @ 1mA	600% @ 5mA	160% @ 5mA	260% @ 5mA
Rise Time (Typ)	3µs	3µs	3µs	3µs	3µs	3µs	3µs	3µs	4µs	4µs	4µs
Fall Time (Typ)	4µs	3µs	3µs	3µs	3µs	3µs	3µs	3µs	3µs	3µs	3µs
Maximum Output Voltage	80V	80V	80V	80V	80V	80V	80V	80V	80V	80V	80V
Maximum Output Current	50mA	80mA	80mA	80mA	80mA	80mA	80mA	80mA	50mA	50mA	50mA
Vce Saturation (Max)	200mV	400mV	400mV	400mV	400mV	400mV	400mV	400mV	200mV	200mV	200mV
Forward Voltage (Vf) Typ	1.2V	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.2V	1.2V	1.2V
Operating Temperature	-55°C to 110°C	-40°C to 110°C	-40°C to 110°C	-40°C to 110°C	-40°C to 110°C	-40°C to 110°C	-40°C to 110°C	-40°C to 110°C	-55°C to 100°C	-55°C to 100°C	-55°C to 100°C
Package Type	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SOIC (0.209", 5.30mm)	4-SMD, Gull Wing	4-SMD, Gull Wing
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Inventory Status	925 Pcs	17900 Pcs	29294 Pcs	2600 Pcs	1308 Pcs	66880 Pcs	7600 Pcs	35200 Pcs	47300 Pcs	1607 Pcs	103100 Pcs

Engineering Selection Recommendations

Primary Equivalent (Identical CTR Range): HCPL-181-00BE is the closest functional equivalent to EL357NB(TA)-VG, matching the Current Transfer Ratio specification of 130% to 260% at 5mA. Both parts share identical Vce saturation (200mV maximum) and forward voltage (1.2V typical) characteristics. The HCPL-181-00BE operates within a narrower temperature range (-55°C to 100°C versus -55°C to 110°C) but maintains full compliance with ROHS3 and MSL 1 requirements. This part is available in 4-Mini-Flat package configuration with 103,100 units in stock.

Secondary Equivalents (Broader CTR Range): FODM121AR2 and FODM121CR2 provide CTR ranges of 100% to 300% and 100% to 200% respectively at 5mA, encompassing the EL357NB(TA)-VG specification. Both onsemi parts support higher maximum output current (80mA versus 50mA) and operate across -40°C to 110°C. FODM121CR2 offers the highest inventory availability at 66,880 units in Tape & Reel packaging. These parts feature 400mV maximum Vce saturation and 1.3V maximum forward voltage.

Alternative with Extended CTR: HCPL-181-000E provides a broader CTR range (50% to 600% at 5mA) while maintaining identical output voltage, current, and saturation specifications to the main part. This Broadcom component operates at -55°C to 100°C and is available in 4-SOIC package with 47,300 units in stock.

High-Gain Option: FODM124R2 offers significantly higher current transfer ratio (100% to 1200% at 1mA) for applications requiring enhanced sensitivity. This part maintains all core electrical specifications and operates across -40°C to 110°C with 35,200 units available.

All substitute parts maintain ROHS3 compliance and MSL 1 rating. Selection should be based on specific CTR requirements, operating temperature constraints, and package form factor compatibility with circuit board design.

Frequently Asked Questions (FAQ)

Q: Can FODM121 series parts directly replace EL357NB(TA)-VG in existing designs?

A: FODM121 series parts are electrically compatible substitutes with matching 3750Vrms isolation voltage, single-channel transistor output, and DC input configuration. However, the onsemi parts feature 80mA maximum output current compared to 50mA for the Everlight part, and operate across -40°C to 110°C rather than -55°C to 110°C. Vce saturation is 400mV maximum versus 200mV for the original part. These differences are acceptable for most applications but should be verified against specific circuit requirements.

Q: What is the significance of Current Transfer Ratio (CTR) variations among substitute parts?

A: CTR determines the ratio of output collector current to input LED current. The EL357NB(TA)-VG specifies 130% to 260% CTR at 5mA input current. Substitute parts with lower minimum CTR (such as FODM121 at 50% minimum) require higher input current to achieve equivalent output switching. Parts with higher maximum CTR (such as FODM124R2 at 1200% maximum) provide greater sensitivity but may require input current limiting. Selection depends on the drive circuit capability and output load requirements.

Q: Are HCPL-181 series parts compatible with FODM121 series parts in the same application?

A: HCPL-181 and FODM121 series parts share identical isolation voltage, output type, and channel configuration. However, they differ in package form factor (4-SOIC versus 4-SMD), Vce saturation (200mV versus 400mV), and operating temperature ranges. Direct substitution requires PCB layout compatibility with the selected package type. The lower Vce saturation of HCPL-181 parts may provide improved output voltage headroom in current-limited applications.

Q: What packaging options are available for substitutes?

A: Substitute parts are available in multiple packaging configurations: 4-SMD Gull Wing (standard surface mount), 4-SOIC (0.209" width), and 4-Mini-Flat. FODM121 series parts are supplied in Tube, Tape & Reel (TR), or Cut Tape (CT) & Digi-Reel® formats. HCPL-181 series parts are available in Cut Tape & Digi-Reel® format. Package selection affects PCB footprint and automated assembly compatibility.

Q: How do operating temperature ranges affect part selection?

A: EL357NB(TA)-VG operates from -55°C to 110°C. FODM121 series substitutes operate from -40°C to 110°C, providing a narrower low-temperature range. HCPL-181 series parts operate from -55°C to 100°C, matching the low-temperature capability but with a lower maximum temperature. Applications requiring full -55°C to 110°C operation should use EL357NB(TA)-VG or verify that substitute parts meet the specific temperature profile required.

Q: What is the difference between FODM121 and FODM124 variants?

A: FODM124R2 is a high-gain variant with CTR of 100% to 1200% at 1mA input current, compared to FODM121 variants with CTR ranges from 50% to 600% at 5mA input current. The FODM124R2 requires lower input current to achieve full output switching, making it suitable for low-power drive circuits. Both parts maintain identical isolation voltage, output specifications, and package configuration.

Q: Are all substitute parts RoHS3 compliant?

A: Yes, all listed substitute parts (FODM121 series, FODM124R2, and HCPL-181 series) are ROHS3 compliant with Moisture Sensitivity Level 1 (unlimited shelf life). This ensures compatibility with modern manufacturing processes and environmental regulations.

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