4N28S(TB) Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N28S(TB) is an optoisolator transistor with base output manufactured by Everlight Electronics Co Ltd. This component provides galvanic isolation up to 5000Vrms with a single channel configuration in a 6-SMD surface mount package. The device is classified as Active product status and is ROHS3 compliant. Substitute parts are identified when equivalent functional performance can be achieved within the allowed electrical and mechanical parameter ranges for optoisolator transistor applications, particularly when inventory availability or specific operational requirements necessitate alternative sourcing.

Key Parameters

Parameter	Value	Unit
Voltage - Isolation	5000	Vrms
Number of Channels	1	—
Current Transfer Ratio (Min)	10	% @ 10mA
Turn On / Turn Off Time (Typ)	3 / 3	µs
Output Type	Transistor with Base	—
Voltage - Output (Max)	80	V
Voltage - Forward (Vf) (Typ)	1.2	V
Current - DC Forward (If) (Max)	60	mA
Vce Saturation (Max)	500	mV
Operating Temperature Range	-55 to 110	°C
Mounting Type	Surface Mount	—
Package / Case	6-SMD, Gull Wing	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the 4N28S(TB) are identified based on the following critical parameters that define functional equivalence in optoisolator transistor applications:

Primary Substitution Criteria:

Output Type: Transistor with Base (mandatory match)
Number of Channels: 1 (mandatory match)
Package / Case: 6-SMD, Gull Wing (mandatory match)
Mounting Type: Surface Mount (mandatory match)
Current Transfer Ratio (Min): 10% @ 10mA (mandatory match)
Vce Saturation (Max): 500mV (mandatory match)
Current - DC Forward (If) (Max): 60 mA (mandatory match)

Secondary Compatibility Parameters:

Voltage - Isolation: Minimum 4170Vrms (acceptable if ≥80% of main part specification)
Voltage - Output (Max): Minimum 30V (acceptable if ≥37.5% of main part specification)
Operating Temperature Range: Must encompass or overlap primary operating window
RoHS Status: ROHS3 Compliant (mandatory match)

The 4N28SM from onsemi qualifies as a substitute part based on these criteria.

Parameter Comparison

Parameter	4N28S(TB) (Everlight)	4N28SM (onsemi)	Compatibility Status
Voltage - Isolation	5000 Vrms	4170 Vrms	Acceptable (83.4% of main part)
Number of Channels	1	1	Match
Current Transfer Ratio (Min)	10% @ 10mA	10% @ 10mA	Match
Turn On / Turn Off Time (Typ)	3 / 3 µs	2 / 2 µs	Compatible (faster response)
Output Type	Transistor with Base	Transistor with Base	Match
Voltage - Output (Max)	80 V	30 V	Acceptable (37.5% of main part)
Voltage - Forward (Vf) (Typ)	1.2 V	1.18 V	Compatible
Current - DC Forward (If) (Max)	60 mA	60 mA	Match
Vce Saturation (Max)	500 mV	500 mV	Match
Operating Temperature Range	-55 to 110 °C	-40 to 100 °C	Partial overlap (-40 to 100 °C)
Mounting Type	Surface Mount	Surface Mount	Match
Package / Case	6-SMD, Gull Wing	6-SMD, Gull Wing	Match
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Match
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	Match

Engineering Selection Recommendations

4N28SM (onsemi) as Substitute:

The 4N28SM qualifies as a functional substitute for the 4N28S(TB) based on matching core electrical and mechanical parameters. Both components are Active product status and ROHS3 compliant. The 4N28SM demonstrates equivalent performance in current transfer ratio, saturation voltage, and forward current specifications. The isolation voltage of 4170Vrms in the 4N28SM is 83.4% of the main part specification, remaining within acceptable tolerance for most optoisolator applications. The maximum output voltage of 30V in the 4N28SM is lower than the 80V specification of the 4N28S(TB); applications requiring output voltages exceeding 30V must retain the original 4N28S(TB) component. The operating temperature range of the 4N28SM (-40 to 100°C) is narrower than the 4N28S(TB) (-55 to 110°C); applications requiring operation below -40°C or above 100°C must retain the original component. Both components share identical packaging, mounting type, and moisture sensitivity classification, enabling direct physical substitution in PCB layouts.

Frequently Asked Questions (FAQ)

Q: Can the 4N28SM replace the 4N28S(TB) in all applications?

A: The 4N28SM is functionally equivalent for applications where output voltage requirements do not exceed 30V and operating temperature remains within -40 to 100°C. Applications requiring higher output voltages or extended temperature operation must use the original 4N28S(TB).

Q: What is the primary difference between these two optoisolators?

A: The main differences are isolation voltage (5000Vrms vs. 4170Vrms), maximum output voltage (80V vs. 30V), and operating temperature range (-55 to 110°C vs. -40 to 100°C). All other electrical and mechanical parameters are equivalent.

Q: Are the packages physically identical?

A: Yes. Both the 4N28S(TB) and 4N28SM use 6-SMD, Gull Wing surface mount packages with identical footprints, enabling direct PCB layout compatibility.

Q: Does the 4N28SM have faster switching speed?

A: The 4N28SM has turn on/off times of 2µs compared to 3µs for the 4N28S(TB). This represents faster switching response and is compatible with applications designed for the original component.

Q: Are both parts RoHS compliant?

A: Yes. Both the 4N28S(TB) and 4N28SM are ROHS3 compliant with MSL rating of 1 (Unlimited), meeting environmental and regulatory requirements for equivalent component selection.

Q: What is the current transfer ratio specification for both parts?

A: Both components specify a minimum current transfer ratio of 10% at 10mA input current, ensuring equivalent optical coupling efficiency.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message