4N28 Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N28 is a single-channel optoisolator with transistor output and base connection, manufactured by Isocom Components 2004 LTD. This component provides galvanic isolation between input and output circuits with a rated isolation voltage of 7.5Vpk. The device is actively produced and widely used in applications requiring DC input signal isolation with transistor-based output control. Substitute parts are identified when equivalent functional performance can be achieved within the specified electrical and mechanical parameters while maintaining the same package form factor and isolation topology.

Substiute Parts

4N28

Isocom Components 2004 LTDIn Stock: 251454N28 Datasheet

Current PartRFQ

4N25-000E

Broadcom LimitedIn Stock: 30614N25-000E Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 4N28 optoisolator is determined by the following critical parameters:

Mandatory Compatibility Criteria:

• Single-channel configuration (Number of Channels = 1)
• Transistor output with base connection (Output Type)
• 6-DIP through-hole package (0.300", 7.62mm)
• DC input type
• Operating temperature range: -55°C ~ 100°C
• Maximum output voltage: 30V or greater
• RoHS3 compliance

Performance Parameters:

• Current Transfer Ratio minimum of 10% or higher at 10mA input
• Forward voltage (Vf) of 1.2V
• Maximum forward current (If) of 60mA or higher
• Vce saturation maximum of 500mV or lower

The 4N25-000E manufactured by Broadcom Limited meets all mandatory compatibility criteria and exceeds performance specifications in current transfer ratio, output current capacity, and isolation voltage rating.

Parameter Comparison

Engineering Selection Recommendations

The 4N25-000E is a direct functional substitute for the 4N28 optoisolator. Both components are actively produced and RoHS3 compliant, meeting regulatory requirements for current applications.

Selection basis:

The 4N25-000E maintains identical package geometry (6-DIP through-hole), output type (transistor with base), and operating temperature range. The substitute part exceeds the 4N28 specification in isolation voltage (2500Vrms vs. 7.5Vpk), current transfer ratio (20% vs. 10%), output current capacity (100mA vs. 50mA), and maximum forward current (80mA vs. 60mA). Rise and fall times are marginally longer (3µs vs. 2µs), which is acceptable for most DC isolation applications where switching speed is not a critical constraint.

Both parts carry identical compliance certifications (ROHS3, REACH Unaffected, EAR99 ECCN classification) and moisture sensitivity level (MSL 1 - Unlimited).

Frequently Asked Questions (FAQ)

Q: Can the 4N25-000E replace the 4N28 in existing circuit designs?

A: Yes. The 4N25-000E is pin-compatible and functionally equivalent. Both use the 6-DIP package with identical pinout for single-channel transistor output optoisolators. No circuit modifications are required for direct substitution.

Q: What is the difference in isolation voltage between these parts?

A: The 4N28 provides 7.5Vpk isolation, while the 4N25-000E provides 2500Vrms isolation. The 4N25-000E exceeds the isolation specification of the 4N28, making it suitable for applications requiring higher isolation ratings.

Q: Are there differences in switching speed?

A: The 4N28 has rise and fall times of 2µs, while the 4N25-000E has rise and fall times of 3µs. For DC signal isolation applications, this 1µs difference is typically not significant. Applications requiring sub-microsecond switching precision should evaluate timing requirements against actual circuit specifications.

Q: Do both parts meet current environmental and compliance standards?

A: Yes. Both the 4N28 and 4N25-000E are RoHS3 compliant, REACH unaffected, and classified as EAR99 for export control purposes. Both carry MSL 1 (Unlimited) moisture sensitivity rating.

Q: What is the maximum output current for each part?

A: The 4N28 supports 50mA maximum output current per channel. The 4N25-000E supports 100mA maximum output current per channel. Applications requiring higher output current can benefit from the 4N25-000E specification.

Q: Are these parts available in different packaging options?

A: Both parts are specified in 6-DIP through-hole package only. The 4N28 is supplied without specified packaging detail, while the 4N25-000E is supplied in tube packaging. Both use identical 0.300" (7.62mm) DIP spacing for PCB mounting.