4N35SD Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N35SD is an optoisolator transistor with base output manufactured by onsemi, rated for 5300Vrms isolation voltage in a 6-SMD surface mount package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

The 4N35SD functions as a single-channel optoisolator with DC input and transistor output with base connection, suitable for high-voltage isolation applications requiring fast switching response (2µs typical turn-on and turn-off times).

Key Parameters

Parameter	Value
Manufacturer Part Number	4N35SD
Manufacturer	onsemi
Category	Optoisolators
Number of Channels	1
Voltage - Isolation	5300Vrms
Current Transfer Ratio (Min)	100% @ 10mA
Turn On / Turn Off Time (Typ)	2µs, 2µs
Input Type	DC
Output Type	Transistor with Base
Voltage - Output (Max)	30V
Voltage - Forward (Vf) (Typ)	1.18V
Current - DC Forward (If) (Max)	100 mA
Vce Saturation (Max)	300mV
Operating Temperature	-55°C ~ 100°C
Mounting Type	Surface Mount
Package / Case	6-SMD, Gull Wing
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the 4N35SD is determined by the following critical parameters:

Isolation Voltage (Vrms): The 4N35SD operates at 5300Vrms. Substitute parts must maintain isolation voltage at or above this level to ensure equivalent safety margins in high-voltage isolation circuits.
Output Configuration: All substitutes must feature transistor output with base connection to maintain circuit compatibility.
Package Type: All substitutes use 6-SMD, Gull Wing surface mount packaging for direct PCB compatibility.
Input Type: DC input requirement is consistent across all substitutes.
Current Transfer Ratio: Minimum 100% @ 10mA is maintained across all substitutes.
Maximum Output Voltage: 30V maximum output voltage is consistent across all substitutes.
Vce Saturation: 300mV maximum saturation voltage is maintained across all substitutes.

Substitutes are grouped into two categories:

Direct Manufacturer Substitutes (onsemi): Parts maintaining the same manufacturer lineage with minor specification variations.

Cross-Manufacturer Alternatives: Parts from Broadcom Limited, Vishay Semiconductor Opto Division, and Lite-On Inc. that meet or exceed the electrical and mechanical requirements of the 4N35SD.

Parameter Comparison

Parameter	4N35SD (Main)	4N35SR2M	4N35-300E	4N35-500E	4N35-X007	4N35-X007T	4N35-X009	4N35-X009T	4N35S-TA	4N35S-TA1	4N35SM
Manufacturer	onsemi	onsemi	Broadcom Limited	Broadcom Limited	Vishay	Vishay	Vishay	Vishay	Lite-On	Lite-On	onsemi
Voltage - Isolation (Vrms)	5300	4170	3550	3550	5000	5000	5000	5000	3550	3550	4170
Current Transfer Ratio (Min)	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA	100% @ 10mA
Turn On / Turn Off Time (Typ)	2µs, 2µs	2µs, 2µs	—	—	10µs, 10µs	10µs, 10µs	10µs, 10µs	10µs, 10µs	—	—	2µs, 2µs
Rise / Fall Time (Typ)	—	—	3µs, 3µs	3µs, 3µs	—	—	—	—	3µs, 3µs	3µs, 3µs	—
Input Type	DC	DC	DC	DC	DC	DC	DC	DC	DC	DC	DC
Output Type	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base
Voltage - Output (Max)	30V	30V	30V	30V	30V	30V	30V	30V	30V	30V	30V
Current - Output / Channel (mA)	—	—	100	100	50	50	50	50	100	100	—
Voltage - Forward (Vf) (Typ)	1.18V	1.18V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.18V
Current - DC Forward (If) (Max)	100 mA	60 mA	60 mA	60 mA	60 mA	60 mA	60 mA	60 mA	60 mA	60 mA	60 mA
Vce Saturation (Max)	300mV	300mV	300mV	300mV	—	—	—	—	300mV	300mV	300mV
Operating Temperature	-55°C ~ 100°C	-40°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-40°C ~ 100°C
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	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	—	REACH Affected	REACH Unaffected

Engineering Selection Recommendations

Highest Compatibility Tier: The 4N35SR2M and 4N35SM (both onsemi) maintain the same manufacturer lineage as the 4N35SD. Both are active products with ROHS3 compliance and REACH Unaffected status. The 4N35SR2M offers 4170Vrms isolation with 2µs switching times, while 4N35SM provides identical electrical characteristics. Both support the full -55°C to 100°C operating range, though the 4N35SR2M and 4N35SM are rated to -40°C minimum.

High Compatibility Tier: The Vishay 4N35-X007, 4N35-X007T, 4N35-X009, and 4N35-X009T parts deliver 5000Vrms isolation, approaching the 4N35SD specification. All are active products with ROHS3 compliance and REACH Unaffected status. These parts feature 10µs switching times (slower than the 4N35SD) and 50mA maximum output current per channel. Operating temperature range is -55°C to 100°C.

Moderate Compatibility Tier: The Broadcom 4N35-300E and 4N35-500E, along with Lite-On 4N35S-TA and 4N35S-TA1, provide 3550Vrms isolation. These represent a reduction in isolation voltage compared to the 4N35SD. All are active products with ROHS3 compliance. The Broadcom parts and Lite-On 4N35S-TA support -55°C to 100°C operation. The Lite-On 4N35S-TA1 is rated -55°C to 100°C but carries REACH Affected status.

Product Status Consideration: All substitute parts are classified as active products, ensuring ongoing availability and manufacturing support. The 4N35SD obsolete status necessitates migration to one of these active alternatives.

Frequently Asked Questions (FAQ)

Q: Can the 4N35SR2M directly replace the 4N35SD?

A: The 4N35SR2M is electrically compatible for most applications. It maintains the same manufacturer (onsemi), identical 2µs switching times, 100% current transfer ratio, and 300mV Vce saturation. The primary difference is reduced isolation voltage (4170Vrms versus 5300Vrms). If your circuit operates below 4170Vrms isolation requirements, the 4N35SR2M is a direct substitute. If your design requires 5300Vrms isolation margin, select a Vishay alternative.

Q: What is the difference between the Vishay 4N35-X007 and 4N35-X009 parts?

A: The 4N35-X007 and 4N35-X009 are electrically identical. Both deliver 5000Vrms isolation, 10µs switching times, and 50mA maximum output current. The difference is packaging: 4N35-X007 is supplied in Tube packaging, while 4N35-X009 is also available in Tube. The 4N35-X007T and 4N35-X009T variants are supplied in Tape & Reel (TR) format for automated assembly.

Q: Why do some substitutes show lower isolation voltage than the 4N35SD?

A: The Broadcom and Lite-On alternatives (3550Vrms) represent a lower isolation rating. These parts are suitable for applications where the circuit isolation requirement is 3550Vrms or lower. For designs requiring the full 5300Vrms isolation margin of the 4N35SD, select onsemi 4N35SR2M or Vishay 4N35-X series parts.

Q: Are all substitutes RoHS3 compliant?

A: All substitute parts listed are RoHS3 compliant. The 4N35SD does not specify RoHS status. All substitutes meet current environmental compliance requirements.

Q: What packaging options are available for these substitutes?

A: Packaging varies by part number. onsemi 4N35SR2M is supplied in Cut Tape (CT) & Digi-Reel format. Broadcom 4N35-300E is supplied in Tube; 4N35-500E in Cut Tape & Digi-Reel. Vishay 4N35-X007 and 4N35-X009 are available in Tube; 4N35-X007T and 4N35-X009T in Tape & Reel. Lite-On 4N35S-TA is supplied in Tape & Reel; 4N35S-TA1 in Cut Tape & Digi-Reel. Select packaging based on your assembly process requirements.

Q: Does operating temperature range affect substitution?

A: The 4N35SD operates -55°C to 100°C. Most substitutes maintain this range. The onsemi 4N35SR2M and 4N35SM are rated -40°C to 100°C, which is acceptable for applications not requiring -55°C operation. Verify your circuit's minimum operating temperature requirement before selecting these parts.

Q: What is the significance of Current Transfer Ratio (CTR)?

A: All listed parts maintain 100% minimum current transfer ratio at 10mA input current. This ensures consistent optical coupling efficiency across all substitutes. CTR determines how much output current flows relative to input current; higher CTR indicates more efficient isolation.

Q: Can I use the 4N35-X007 in place of the 4N35SD in a high-speed switching application?

A: The 4N35-X007 has 10µs switching times compared to the 4N35SD's 2µs. If your circuit requires fast switching response below 10µs, the 4N35-X007 is not suitable. Select the onsemi 4N35SR2M or 4N35SM, which maintain 2µs switching performance.

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