4N28SM

Overview

The onsemi 4N28SM is a surface-mount transistor output optocoupler featuring a single channel. It utilizes an infrared LED coupled to an NPN phototransistor for signal isolation. The device provides a high isolation voltage of 4170 Vrms, ensuring robust protection between input and output circuits. It is housed in a compact 6-pin SMD package designed for automated assembly processes. The component supports DC input signals and offers standard switching characteristics suitable for general-purpose digital isolation applications in industrial and consumer electronics.

Feature Summary

• High voltage isolation capability of 4170 Vrms for safe circuit separation
• Surface mount design compatible with automated pick-and-place manufacturing
• Infrared LED source paired with NPN phototransistor for efficient signal transfer

Applications

• Industrial control system signal isolation
• Consumer electronics interface protection
• General-purpose digital communication isolation

Procurement Notes

Verify the specific datasheet version when sourcing, as pinout configurations and electrical limits can vary between manufacturers offering equivalent part numbers. Confirm that the 6-pin SMD footprint matches the target PCB layout requirements. Ensure compliance with RoHS directives if required by the end product specifications. Cross-reference the manufacturer's official documentation for thermal derating curves and storage conditions prior to integration.

Selection Notes

Select this component when a low-cost, single-channel isolation solution is required for space-constrained designs. The surface mount package facilitates high-volume production efficiency compared to through-hole alternatives. Consider the propagation delay and rise/fall times against the system's switching speed requirements. Evaluate the operating temperature range to ensure reliability under expected environmental conditions.

Part Context

This device belongs to the broader category of transistor output optocouplers, which are fundamental components for galvanic isolation in electronic circuits. It serves as a direct replacement or alternative to other industry-standard DIP-6 optocouplers adapted for surface mount technology. The family typically emphasizes cost-effectiveness and basic isolation performance for non-critical signal paths.

Replacement Considerations

Direct replacements must match the 6-pin SMD footprint and maintain similar isolation voltage ratings. Verify that substitute parts offer comparable current transfer ratios and switching speeds. Check for any differences in lead-free soldering compatibility if rework is anticipated.