PC123P Optoisolator Equivalent & Substitute Parts

Part Overview

The PC123P is a 5000Vrms isolation optoisolator with transistor output manufactured by Sharp Microelectronics. This component features single-channel isolation in a 4-SMD surface mount package with 50mA output current capability and 70V maximum output voltage. The PC123P is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Active alternatives from onsemi and Fairchild Semiconductor provide direct functional replacement with enhanced product status and compliance certifications.

Key Parameters

Parameter	Value
Voltage - Isolation	5000Vrms
Number of Channels	1
Output Type	Transistor
Voltage - Output (Max)	70V
Current - Output / Channel	50mA
Voltage - Forward (Vf) (Typ)	1.2V
Current - DC Forward (If) (Max)	50mA
Vce Saturation (Max)	200mV
Rise / Fall Time (Typ)	4µs, 3µs
Input Type	DC
Mounting Type	Surface Mount
Package / Case	4-SMD, Gull Wing
Operating Temperature	-30°C ~ 100°C

Substitute Part Grouping Explanation

Substitution eligibility for the PC123P is determined by strict equivalence across the following critical parameters:

Voltage - Isolation: 5000Vrms (mandatory match)
Number of Channels: 1 (mandatory match)
Output Type: Transistor (mandatory match)
Voltage - Output (Max): 70V (mandatory match)
Current - Output / Channel: 50mA (mandatory match)
Package / Case: 4-SMD, Gull Wing (mandatory match)
Mounting Type: Surface Mount (mandatory match)

All substitute parts listed meet these core electrical and mechanical requirements. Variations in Current Transfer Ratio, operating temperature range, and product status are secondary parameters that do not prevent functional substitution but may influence selection based on application requirements and supply chain considerations.

Parameter Comparison

Parameter	PC123P (Sharp)	FOD8173S (Fairchild)	FOD8173SD (Fairchild)	FOD817A3S (onsemi)	FOD817A3SD (onsemi)	FOD817AS (onsemi)	FOD817ASD (onsemi)	FOD817B3S (onsemi)	FOD817B3SD (onsemi)	FOD817BS (onsemi)	FOD817BSD (onsemi)
Voltage - Isolation	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms
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
Voltage - Output (Max)	70V	70V	70V	70V	70V	70V	70V	70V	70V	70V	70V
Current - Output / Channel	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA
Voltage - Forward (Vf) (Typ)	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V
Current - DC Forward (If) (Max)	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA
Vce Saturation (Max)	200mV	200mV	200mV	200mV	200mV	200mV	200mV	200mV	200mV	200mV	200mV
Rise / Fall Time (Typ)	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs	4µs, 3µs
Input Type	DC	DC	DC	DC	DC	DC	DC	DC	DC	DC	DC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	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	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing	4-SMD, Gull Wing
Operating Temperature	-30°C ~ 100°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C	-55°C ~ 110°C
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

All listed substitute parts provide electrical and mechanical equivalence to the PC123P. Selection among available options should be based on the following factors:

Product Status: All substitute parts carry Active product status, ensuring long-term availability and manufacturing support. The PC123P's Obsolete classification makes transition to an active alternative necessary for production continuity.

Compliance & Certifications: onsemi FOD817 series parts (FOD817A3S, FOD817A3SD, FOD817AS, FOD817ASD, FOD817B3S, FOD817B3SD, FOD817BS, FOD817BSD) are ROHS3 Compliant and REACH Unaffected, with Moisture Sensitivity Level 1 (Unlimited). Fairchild FOD8173S and FOD8173SD parts do not specify these compliance certifications in the provided data.

Operating Temperature Range: Substitute parts extend the operating temperature range to -55°C ~ 110°C compared to the PC123P's -30°C ~ 100°C, providing broader environmental capability.

Current Transfer Ratio: Fairchild FOD8173 series offers 50% to 600% CTR @ 5mA. onsemi FOD817A series provides 80% to 160% CTR @ 5mA. onsemi FOD817B series provides 130% to 260% CTR @ 5mA. Selection depends on circuit requirements for gain characteristics.

Packaging Options: onsemi FOD817 variants are available in Tube, Cut Tape (CT) & Digi-Reel, and Tape & Reel (TR) formats. Fairchild FOD8173 variants are available in Bulk and Cut Tape formats. Choose based on procurement and assembly requirements.

Frequently Asked Questions (FAQ)

Q: Can FOD817A3S directly replace PC123P in existing designs? A: Yes. FOD817A3S meets all mandatory electrical and mechanical parameters: 5000Vrms isolation, single-channel transistor output, 70V maximum output voltage, 50mA output current, and 4-SMD Gull Wing package. The part is pin-compatible and functionally equivalent.

Q: What is the difference between FOD817A and FOD817B variants? A: Both are functionally equivalent substitutes for PC123P. The primary difference is Current Transfer Ratio specification: FOD817A provides 80% to 160% CTR @ 5mA, while FOD817B provides 130% to 260% CTR @ 5mA. Select based on circuit gain requirements.

Q: Are onsemi FOD817 parts RoHS compliant? A: Yes. All onsemi FOD817 variants listed are ROHS3 Compliant with Moisture Sensitivity Level 1 (Unlimited), providing superior compliance compared to the obsolete PC123P.

Q: What packaging format should I choose for high-volume production? A: For automated assembly, select Cut Tape (CT) & Digi-Reel or Tape & Reel (TR) formats such as FOD817A3SD, FOD817ASD, FOD817B3SD, or FOD817BSD. For manual assembly or lower volumes, Tube packaging (FOD817A3S, FOD817AS, FOD817B3S, FOD817BS) is appropriate.

Q: Is the extended operating temperature range of substitutes a concern? A: No. The substitute parts' extended range (-55°C ~ 110°C) is a superset of the PC123P's range (-30°C ~ 100°C). This provides additional environmental capability without affecting compatibility in applications designed for the original part's temperature limits.

Q: Can I use Fairchild FOD8173S instead of onsemi FOD817A? A: Yes. Both meet all mandatory substitution criteria. FOD8173S offers higher Current Transfer Ratio range (50% to 600% @ 5mA) compared to FOD817A (80% to 160% @ 5mA). Selection depends on circuit design requirements for gain characteristics and available inventory.

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