LTC4257IS8-1#PBF

Overview

The LTC4257IS8-1#PBF is a Powered Device (PD) power switch IC compliant with IEEE 802.3af standards, designed for Power over Ethernet applications. It integrates an internal controller and two N-channel pass transistors to manage power delivery. The device operates within a supply voltage range of -4V to -57V and supports a maximum current limit of 375mA. It features a typical on-resistance of 2 Ohms and functions reliably across an industrial temperature range from -40°C to +85°C. Packaged in an 8-pin SOIC, it provides essential protection mechanisms including reverse polarity protection and thermal shutdown.

Feature Summary

• Integrates dual N-channel pass transistors with internal control logic for simplified PoE PD implementation
• Provides comprehensive protection against reverse polarity, overcurrent, and thermal overload conditions
• Supports hot insertion capabilities to allow connection without disrupting existing network infrastructure

Applications

• IEEE 802.3af compliant Powered Devices such as VoIP phones and wireless access points
• Network surveillance cameras requiring integrated power management
• Industrial sensor nodes utilizing Power over Ethernet for data and power transmission

Procurement Notes

Verify the specific suffix and package configuration against official Analog Devices documentation to ensure compatibility with design requirements. Confirm availability status through authorized distributors as supply levels may vary. Ensure compliance with RoHS directives and verify that the component meets the required industrial temperature specifications for the intended application environment.

Selection Notes

Select this component for designs requiring a compact, single-chip solution for IEEE 802.3af powered devices. It is suitable for applications needing integrated reverse polarity protection and current limiting without external discrete components. Consider the SOIC-8 package constraints and operating voltage range when evaluating system architecture and thermal management strategies.

Part Context

This part belongs to the LTC4257 family of PoE power switches manufactured by Analog Devices. It is specifically engineered for low-cost, high-reliability implementations in networked endpoints. The device simplifies board layout by combining the power switch and controller into a single package, reducing the overall component count compared to discrete solutions.

Replacement Considerations

Direct substitutes include other variants within the LTC4257 series such as the LTC4257CS8-1#PBF or LTC4257IDD-1#PBF, which offer similar functionality but may differ in temperature grade or package type. Verify pinout compatibility and electrical specifications before substitution.