SFH655A Optoisolator Equivalent & Substitute Parts

Part Overview

The SFH655A is a 5300Vrms isolation optoisolator with Darlington output manufactured by Vishay Semiconductor Opto Division in a 4-DIP package. This component is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. The part delivers 1 channel of galvanic isolation with 600% minimum current transfer ratio at 1mA input current, suitable for applications requiring high-voltage isolation with Darlington output switching capability.

Key Parameters

Parameter	SFH655A
Manufacturer	Vishay Semiconductor Opto Division
Product Status	Obsolete
Number of Channels	1
Voltage - Isolation	5300Vrms
Current Transfer Ratio (Min)	600% @ 1mA
Output Type	Darlington
Voltage - Output (Max)	55V
Current - Output / Channel	125mA
Package / Case	4-DIP (0.300", 7.62mm)
Operating Temperature	-55°C ~ 100°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the SFH655A is determined by the following critical parameters:

Single-channel Darlington output optoisolator configuration
4-DIP through-hole package format (0.300", 7.62mm)
Minimum 5000Vrms isolation voltage (SFH655A specifies 5300Vrms)
Minimum 600% current transfer ratio at 1mA
DC input type compatibility
Operating temperature range overlap with -55°C minimum
ROHS3 compliance and MSL 1 rating

The substitute parts EL815, LTV-8141, and LTV-815 meet these core substitution criteria. All three are active-status optoisolators with Darlington outputs in 4-DIP packages, providing 5000Vrms isolation with 600% minimum current transfer ratio. Differences in maximum output voltage (35V vs 55V) and output current (80mA vs 125mA) represent design trade-offs that must be evaluated against specific application requirements.

Parameter Comparison

Parameter	SFH655A	EL815	LTV-8141	LTV-815
Manufacturer	Vishay	Everlight Electronics	Lite-On Inc.	Lite-On Inc.
Product Status	Obsolete	Active	Active	Active
Number of Channels	1	1	1	1
Voltage - Isolation	5300Vrms	5000Vrms	5000Vrms	5000Vrms
Current Transfer Ratio (Min)	600% @ 1mA	600% @ 1mA	600% @ 1mA	600% @ 1mA
Output Type	Darlington	Darlington	Darlington	Darlington
Voltage - Output (Max)	55V	35V	35V	35V
Current - Output / Channel	125mA	80mA	80mA	80mA
Input Type	DC	DC	AC, DC	DC
Package / Case	4-DIP (0.300", 7.62mm)	4-DIP (0.300", 7.62mm)	4-DIP (0.300", 7.62mm)	4-DIP (0.300", 7.62mm)
Operating Temperature	-55°C ~ 100°C	-55°C ~ 110°C	-30°C ~ 100°C	-30°C ~ 100°C
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

All three substitute parts—EL815, LTV-8141, and LTV-815—are active-status components with current manufacturing support, addressing the obsolescence of the SFH655A. Each maintains ROHS3 compliance and MSL 1 rating, ensuring regulatory and environmental compatibility with the original part.

EL815 (Everlight Electronics) extends the operating temperature range to 110°C maximum, providing thermal margin beyond the SFH655A specification. LTV-8141 (Lite-On) accepts both AC and DC input signals, offering broader input flexibility compared to the DC-only SFH655A. LTV-815 (Lite-On) maintains DC-only input matching the original part specification.

The primary design consideration is the reduction in maximum output voltage from 55V to 35V and output current from 125mA to 80mA across all substitutes. Applications operating within these reduced electrical limits can proceed with any of the three options. Applications requiring the full 55V/125mA output capability require design modification or alternative component selection outside this substitute group.

Frequently Asked Questions (FAQ)

Q: Can EL815, LTV-8141, and LTV-815 be used interchangeably with SFH655A?

A: These parts share the same 4-DIP package, single-channel Darlington output configuration, and minimum 600% current transfer ratio. However, the 35V maximum output voltage and 80mA output current of the substitutes are lower than the SFH655A specifications of 55V and 125mA. Interchangeability depends on whether your application operates within these reduced electrical limits.

Q: What is the isolation voltage difference between SFH655A and the substitutes?

A: SFH655A provides 5300Vrms isolation, while EL815, LTV-8141, and LTV-815 each provide 5000Vrms isolation. This 300Vrms difference represents a 5.7% reduction. Applications with fixed isolation requirements below 5000Vrms are unaffected; applications requiring the full 5300Vrms specification cannot use these substitutes.

Q: Does input signal type affect substitution compatibility?

A: SFH655A accepts DC input only. EL815 and LTV-815 also accept DC input only, maintaining direct compatibility. LTV-8141 accepts both AC and DC input, providing additional flexibility but not required for DC-only applications.

Q: Are all substitutes available in the same package format?

A: Yes. SFH655A, EL815, LTV-8141, and LTV-815 are all supplied in 4-DIP (0.300", 7.62mm) through-hole packages. Direct PCB footprint compatibility is maintained across all parts.

Q: What are the temperature operating range differences?

A: SFH655A operates from -55°C to 100°C. EL815 extends to 110°C maximum. LTV-8141 and LTV-815 operate from -30°C to 100°C, with a narrower low-temperature range. Applications requiring -55°C minimum operation should select EL815 or confirm that LTV-8141/LTV-815 meet the actual system requirement.

Q: Are all parts RoHS3 compliant?

A: Yes. SFH655A, EL815, LTV-8141, and LTV-815 are all ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, ensuring regulatory and environmental compatibility.

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