IS357B

Overview

The IS357B is a single-channel phototransistor output optocoupler manufactured by Isocom Components. It features an infrared emitting diode coupled to a silicon phototransistor in a compact SOP-4 surface-mount package. The device provides electrical isolation with a rated RMS isolation voltage of 3750V. Key electrical parameters include a typical forward voltage of 1.2V at a forward current of 50mA, and an output voltage capability of 80V. The current transfer ratio (CTR) ranges from 130% to 260%, ensuring reliable signal transmission across the isolation barrier for digital logic applications.

Feature Summary

• Provides high-voltage electrical isolation between input and output circuits using infrared light transmission.
• Integrates a high-gain phototransistor output suitable for direct interfacing with digital logic families.
• Utilizes a compact SOP-4 surface-mount package designed for automated assembly and space-constrained PCB layouts.

Applications

• Logic-to-logic isolation in noisy industrial environments
• Line receiver circuits for data communication interfaces
• Programmable current level sensing applications

Procurement Notes

Verify the specific suffix or variant code against the manufacturer's official datasheet to confirm pinout compatibility and insulation ratings. Ensure the procurement source provides traceability documentation confirming compliance with RoHS directives and relevant safety standards such as UL or VDE recognition. Cross-reference the component marking with official Isocom Components identification guides to prevent counterfeit substitution.

Selection Notes

Select this component when a single-channel isolation solution with moderate current transfer gain is required for low-power digital signaling. The SOP-4 package is appropriate for surface-mount technology processes where board space is limited. Consider the CTR range and isolation voltage requirements relative to the system's noise immunity needs and safety certification constraints before finalizing the design.

Part Context

Isocom Components specializes in photocoplers and optically coupled isolators, often serving as industry-standard replacements for discontinued parts from other manufacturers. The company maintains production facilities and engineering support to ensure supply continuity for critical isolation components used in industrial, commercial, and legacy electronic systems.

Replacement Considerations

Consult official Isocom cross-reference lists for verified equivalent part numbers. Verify that any substitute matches the original pin configuration, isolation voltage rating, and package dimensions to ensure mechanical and electrical compatibility without circuit redesign.