EL817(D) Optoisolator Equivalent & Substitute Parts

Part Overview

The EL817(D) is a 5000Vrms isolation optoisolator with transistor output manufactured by Everlight Electronics Co Ltd. This component is classified as an active product and is designed for DC input applications requiring galvanic isolation in 4-DIP through-hole packages. The EL817(D) operates across an industrial temperature range of -55°C to 110°C and delivers 50mA output current per channel with a maximum output voltage of 35V.

Equivalent and substitute parts are identified based on matching electrical isolation specifications, output characteristics, package form factor, and thermal operating range. Alternative sources provide design flexibility, supply chain redundancy, and component availability across multiple manufacturers.

Key Parameters

Parameter	EL817(D) Value	Unit	Substitution Relevance
Voltage - Isolation	5000	Vrms	Critical - Must match exactly
Number of Channels	1	Channel	Critical - Must match exactly
Output Type	Transistor	Type	Critical - Must match exactly
Current Transfer Ratio (Min)	300	% @ 5mA	Important - Affects circuit performance
Current Transfer Ratio (Max)	600	% @ 5mA	Important - Affects circuit performance
Voltage - Output (Max)	35	V	Important - Determines load voltage capability
Current - Output / Channel	50	mA	Critical - Must match or exceed
Package / Case	4-DIP (0.300", 7.62mm)	Form Factor	Critical - Must match for PCB compatibility
Operating Temperature	-55 to 110	°C	Important - Determines environmental suitability
Mounting Type	Through Hole	Type	Critical - Must match PCB design
Rise / Fall Time (Typ)	4µs, 3µs	µs	Important - Affects switching speed
Vce Saturation (Max)	200	mV	Important - Affects output voltage drop

Substitute Part Grouping Explanation

Substitute parts for the EL817(D) are classified into two categories based on electrical and mechanical compatibility:

Direct Substitutes (Electrical & Mechanical Match): Parts that maintain identical or superior specifications across all critical parameters: 5000Vrms isolation voltage, 1-channel transistor output, 4-DIP through-hole package, 50mA output current, and -55°C to 110°C operating temperature range.

Parametric Equivalents (Functional Match with Minor Variations): Parts that satisfy the core functional requirements but may exhibit differences in secondary parameters such as Current Transfer Ratio ranges, maximum output voltage, or forward voltage characteristics. These parts remain electrically compatible within the application's design margins.

Substitution Logic: All listed parts share the following mandatory matching criteria:

Voltage - Isolation: 5000Vrms (exact match required)
Number of Channels: 1 (exact match required)
Output Type: Transistor (exact match required)
Package / Case: 4-DIP (0.300", 7.62mm) (exact match required)
Mounting Type: Through Hole (exact match required)
Current - Output / Channel: 50mA (exact match required)
Operating Temperature: -55°C to 110°C (exact match required)

Secondary parameters including Current Transfer Ratio, maximum output voltage, and rise/fall times may vary within acceptable engineering tolerances for circuit operation.

Parameter Comparison

Part Number	Manufacturer	Isolation Voltage (Vrms)	CTR Min (% @ 5mA)	CTR Max (% @ 5mA)	Vout Max (V)	Iout (mA)	Vce Sat Max (mV)	Rise/Fall Time (µs)	Temp Range (°C)	Package
EL817(D)	Everlight Electronics	5000	300	600	35	50	200	4, 3	-55 to 110	4-DIP
FOD817300	Fairchild Semiconductor	5000	50	600	70	50	200	4, 3	-55 to 110	4-DIP
FOD817A300	onsemi	5000	80	160	70	50	200	4, 3	-55 to 110	4-DIP
FOD817B300	onsemi	5000	130	260	70	50	200	4, 3	-55 to 110	4-DIP
FOD817C300	onsemi	5000	200	400	70	50	200	4, 3	-55 to 110	4-DIP
FOD817D300	Fairchild Semiconductor	5000	300	600	70	50	200	4, 3	-55 to 110	4-DIP
140817140410	Würth Elektronik	5000	300	600	35	50	200	3, 4	-55 to 110	4-DIP

Engineering Selection Recommendations

Primary Selection - FOD817D300 (Fairchild Semiconductor): The FOD817D300 provides exact electrical parameter matching to the EL817(D) across Current Transfer Ratio (300-600% @ 5mA), maximum output voltage (70V exceeds 35V requirement), and all critical isolation and package specifications. This part is ROHS3 compliant and maintains active product status with 8580 units in stock.

Secondary Selection - 140817140410 (Würth Elektronik): The 140817140410 from Würth Elektronik delivers identical Current Transfer Ratio performance (300-600% @ 5mA) and matches the EL817(D) output voltage specification at 35V maximum. This part carries ROHS3 compliance and MSL Level 1 rating, with 1087 units available. Rise and fall times are reversed (3µs, 4µs) compared to the primary part but remain within equivalent switching performance.

Tertiary Selection - FOD817C300 (onsemi): The FOD817C300 provides Current Transfer Ratio range of 200-400% @ 5mA with maximum output voltage of 70V. This part is suitable for applications where the lower CTR minimum (200% vs. 300%) remains within circuit design margins. ROHS3 compliant with 32088 units in stock.

Compliance & Availability: All substitute parts maintain ROHS3 compliance status and REACH unaffected classification. All parts are classified as active products. Packaging variations (Tube vs. Bulk) do not affect electrical or mechanical compatibility. Selection should prioritize inventory availability and lead time requirements alongside electrical parameter matching.

Frequently Asked Questions (FAQ)

Q: Can FOD817A300 replace EL817(D) in all applications? A: FOD817A300 shares the 5000Vrms isolation voltage, 4-DIP package, and 50mA output current. However, its Current Transfer Ratio range (80-160% @ 5mA) is significantly lower than EL817(D) (300-600% @ 5mA). Substitution is valid only if circuit design accommodates reduced CTR performance and does not require minimum CTR of 300%.

Q: What is the difference between FOD817B300 and FOD817C300? A: Both parts are manufactured by onsemi in 4-DIP packages with 5000Vrms isolation. FOD817B300 has CTR range of 130-260% @ 5mA, while FOD817C300 has CTR range of 200-400% @ 5mA. FOD817C300 provides higher minimum CTR (200% vs. 130%) and is preferred for applications requiring stronger optical coupling performance.

Q: Is the 70V maximum output voltage of FOD817 series a problem if EL817(D) specifies 35V? A: No. The 70V specification indicates the maximum voltage the output transistor can withstand. The EL817(D) specification of 35V is the recommended operating maximum. FOD817 series with 70V rating provides additional voltage margin and is fully compatible with circuits designed for 35V operation.

Q: Does packaging type (Tube vs. Bulk) affect electrical performance? A: No. Tube and Bulk packaging are shipping and storage formats only. Electrical specifications, performance characteristics, and component functionality remain identical. Selection between Tube and Bulk depends on procurement quantity and handling requirements.

Q: Can I use 140817140410 if my circuit requires exactly 4µs rise time and 3µs fall time? A: The 140817140410 specifies 3µs rise time and 4µs fall time (reversed order). Both parts deliver equivalent switching speed performance. If your circuit design requires the exact sequence of 4µs rise followed by 3µs fall, verify with circuit simulation that the reversed timing does not impact system performance.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All listed substitute parts carry ROHS3 Compliant status. The EL817(D) and all FOD817 variants (FOD817300, FOD817A300, FOD817B300, FOD817C300, FOD817D300) and the 140817140410 are ROHS3 compliant.

Q: What is the minimum Current Transfer Ratio I should design for when using FOD817300? A: FOD817300 specifies minimum CTR of 50% @ 5mA. This is significantly lower than EL817(D) (300% minimum). Circuit design must accommodate this lower minimum value. If your application requires minimum CTR of 300%, use FOD817D300 or 140817140410 instead.

Q: Can these parts be used interchangeably on the same PCB? A: Yes. All parts share identical 4-DIP (0.300", 7.62mm) package dimensions and through-hole pin configuration. PCB layout and footprints are fully compatible across all listed parts. No PCB redesign is required for substitution.

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