PS2705-1 Optoisolator Equivalent & Substitute Parts

Part Overview

The PS2705-1 is an optoisolator with transistor output manufactured by CEL, rated for 3750Vrms isolation voltage in a 4-SOP surface mount package. This component is listed as obsolete and has been superseded by functionally equivalent alternatives from active manufacturers. Direct substitutes are available from onsemi and compatible alternatives from Broadcom Limited, Lite-On Inc., and Vishay Semiconductor Opto Division.

Key Parameters

Parameter	PS2705-1
Manufacturer	CEL
Product Status	Obsolete
Number of Channels	1
Voltage - Isolation	3750Vrms
Current Transfer Ratio (Min)	50% @ 5mA
Current Transfer Ratio (Max)	300% @ 5mA
Rise / Fall Time	3µs / 5µs
Input Type	AC, DC
Output Type	Transistor
Voltage - Output (Max)	40V
Current - Output / Channel	80mA
Voltage - Forward (Vf) (Typ)	1.1V
Current - DC Forward (If) (Max)	50mA
Vce Saturation (Max)	300mV
Operating Temperature	-55°C ~ 100°C
Mounting Type	Surface Mount
Package / Case	4-SMD, Gull Wing
RoHS Status	RoHS non-compliant
REACH Status	REACH Affected

Substitute Part Grouping Explanation

Substitution logic for the PS2705-1 is based on the following critical parameters:

Primary Substitution Criteria:

Voltage - Isolation: 3750Vrms (mandatory match)
Number of Channels: 1 (mandatory match)
Input Type: AC, DC (mandatory match)
Output Type: Transistor (mandatory match)
Mounting Type: Surface Mount (mandatory match)
Package compatibility: 4-SMD or equivalent pinout

Upgrade Substitutes (FODM2705, FODM2705R2, FODM2705R2V): These onsemi parts maintain identical isolation voltage, channel count, input/output characteristics, and pinout. Differences in forward voltage (1.4V vs. 1.1V), operating temperature range (-40°C ~ 110°C vs. -55°C ~ 100°C), and packaging format (Tube or Tape & Reel) are within acceptable tolerances for direct replacement. These parts are RoHS3 compliant and REACH unaffected, addressing regulatory limitations of the obsolete PS2705-1.

Similar Alternatives (HCPL-354-000E, LTV-354T, SFH691AT): These parts maintain the same 3750Vrms isolation voltage and single-channel transistor output configuration but have reduced maximum output voltage (35V) or different output current ratings (50mA vs. 80mA for PS2705-1). Package variations include 4-Mini-Flat (HCPL-354-000E) and standard 4-SOP formats. These parts are suitable for applications where the lower ratings do not represent a constraint.

Parameter Comparison

Parameter	PS2705-1 (CEL)	FODM2705 (onsemi)	FODM2705R2 (onsemi)	FODM2705R2V (onsemi)	HCPL-354-000E (Broadcom)	LTV-354T (Lite-On)	SFH691AT (Vishay)
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
Number of Channels	1	1	1	1	1	1	1
Voltage - Isolation	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms
Current Transfer Ratio (Min)	50% @ 5mA	50% @ 5mA	50% @ 5mA	50% @ 5mA	20% @ 1mA	20% @ 1mA	50% @ 5mA
Current Transfer Ratio (Max)	300% @ 5mA	300% @ 5mA	300% @ 5mA	300% @ 5mA	400% @ 1mA	400% @ 1mA	300% @ 5mA
Input Type	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC
Output Type	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor	Transistor
Voltage - Output (Max)	40V	40V	40V	40V	35V	35V	70V
Current - Output / Channel	80mA	80mA	80mA	80mA	50mA	50mA	50mA
Voltage - Forward (Vf) (Typ)	1.1V	1.4V (Max)	1.4V (Max)	1.4V (Max)	1.2V	1.2V	1.15V
Current - DC Forward (If) (Max)	50mA	50mA	50mA	50mA	50mA	50mA	50mA
Vce Saturation (Max)	300mV	300mV	300mV	300mV	200mV	200mV	300mV
Operating Temperature	-55°C ~ 100°C	-40°C ~ 110°C	-40°C ~ 110°C	-40°C ~ 110°C	-55°C ~ 100°C	-30°C ~ 110°C	-55°C ~ 100°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	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
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Affected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

First Priority: onsemi FODM2705, FODM2705R2, FODM2705R2V

These parts provide the closest electrical match to the PS2705-1 while addressing the obsolescence issue. All three variants maintain identical isolation voltage (3750Vrms), current transfer ratio specifications (50%-300% @ 5mA), output voltage (40V), and output current (80mA). The onsemi parts are RoHS3 compliant and REACH unaffected, eliminating the regulatory constraints of the obsolete CEL part. Selection between the three onsemi variants should be based on packaging preference: FODM2705 (Tube), FODM2705R2 (Tape & Reel), or FODM2705R2V (Tape & Reel with additional qualification).

Secondary Priority: Broadcom HCPL-354-000E and Lite-On LTV-354T

These parts maintain the 3750Vrms isolation voltage and single-channel transistor output but have reduced maximum output current (50mA vs. 80mA for PS2705-1) and output voltage (35V vs. 40V). Use these alternatives only in applications where the lower current and voltage ratings do not constrain circuit operation. Both parts are RoHS3 compliant and REACH unaffected. The HCPL-354-000E uses a 4-Mini-Flat package, which may require layout adjustment.

Tertiary Priority: Vishay SFH691AT

The SFH691AT maintains the 3750Vrms isolation voltage, 50%-300% current transfer ratio, and 300mV Vce saturation of the PS2705-1. It offers a higher maximum output voltage (70V) compared to the PS2705-1 (40V). This part is RoHS3 compliant and REACH unaffected. Consider this option for applications requiring the extended output voltage rating.

Frequently Asked Questions (FAQ)

Q: Why is the PS2705-1 obsolete? A: The PS2705-1 is listed as an obsolete product by the original manufacturer CEL. Active alternatives meeting the same electrical specifications are available from multiple qualified manufacturers.

Q: Are the onsemi FODM2705 variants electrically identical to the PS2705-1? A: The FODM2705, FODM2705R2, and FODM2705R2V are electrically equivalent for the primary functional parameters: 3750Vrms isolation voltage, 1 channel, AC/DC input, transistor output, 40V maximum output voltage, and 80mA output current. The forward voltage specification differs (1.4V maximum vs. 1.1V typical), and the operating temperature range extends to 110°C (vs. 100°C for PS2705-1), both in favor of the substitutes.

Q: What is the difference between FODM2705, FODM2705R2, and FODM2705R2V? A: All three parts are electrically identical. The differences are packaging: FODM2705 is supplied in Tube format, FODM2705R2 is supplied in Tape & Reel, and FODM2705R2V is supplied in Tape & Reel with additional qualification markers.

Q: Can I use HCPL-354-000E or LTV-354T as direct replacements? A: These parts have the same isolation voltage (3750Vrms) and transistor output configuration but reduced maximum output current (50mA vs. 80mA) and maximum output voltage (35V vs. 40V). Use only if your circuit operates within these lower ratings.

Q: What is the difference between the HCPL-354-000E and LTV-354T packages? A: The HCPL-354-000E uses a 4-Mini-Flat package, while the LTV-354T uses a standard 4-SOP package. The PS2705-1 also uses 4-SOP, making the LTV-354T a closer package match. The 4-Mini-Flat package of the HCPL-354-000E may require PCB layout modifications.

Q: Why are the Broadcom and Lite-On parts listed as similar rather than direct upgrades? A: The HCPL-354-000E and LTV-354T have lower maximum output current (50mA) and output voltage (35V) specifications than the PS2705-1 (80mA and 40V). These parts are compatible only when circuit requirements do not exceed their lower ratings. The onsemi FODM2705 variants match the full specification envelope and are preferred.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All substitute parts listed (FODM2705, FODM2705R2, FODM2705R2V, HCPL-354-000E, LTV-354T, and SFH691AT) are RoHS3 compliant, while the original PS2705-1 is RoHS non-compliant.

Q: Are all substitute parts REACH unaffected? A: Yes. All substitute parts are REACH unaffected. The original PS2705-1 is REACH affected.

Q: What is the minimum current transfer ratio for these parts? A: The onsemi FODM2705 variants and Vishay SFH691AT maintain a 50% minimum current transfer ratio at 5mA. The Broadcom HCPL-354-000E and Lite-On LTV-354T have a 20% minimum current transfer ratio at 1mA.

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