LT4275BHDD#PBF

Overview

The LT4275BHDD#PBF is a Powered Device (PD) controller supporting IEEE 802.3at PoE+ and LTPoE++ standards, delivering up to 25.5W. It operates within an absolute maximum input voltage of 100V and features a wide junction temperature range from -40°C to 125°C. The device utilizes an internal charge pump to drive an external N-channel MOSFET, eliminating the need for P-channel alternatives. It includes integrated signature resistance, UVLO, thermal protection, and power-good output. The component is available in a 10-lead MSOP package or a 3mm x 3mm DFN-10-EP package.

Feature Summary

• Supports LTPoE++, IEEE 802.3at, and IEEE 802.3af standards with proprietary classification schemes
• Integrates charge pump for N-channel MOSFET drive to maximize efficiency and minimize heat dissipation
• Includes onboard signature resistor, under-voltage lockout, and thermal shutdown protection
• Features programmable auxiliary power support via AUX pin and selectable non-standard low-voltage operation

Applications

• High-power wireless data systems
• Outdoor security camera equipment
• Commercial and public information displays
• High-temperature industrial applications

Procurement Notes

Verify the specific suffix DD against the datasheet to confirm the MSOP package variant versus the IDD DFN variant. Confirm RoHS compliance status through official Analog Devices documentation. Check current availability as distribution channels may indicate limited stock or discontinuation. Ensure the ordering part number matches the required package type for PCB layout compatibility.

Selection Notes

Select this controller for designs requiring PoE+ power levels up to 25.5W with high efficiency. The internal charge pump simplifies design by allowing the use of lower-cost N-channel MOSFETs. Consider the auxiliary power pin if system requirements demand power supplementation during startup or low-PSE conditions. Verify thermal management capabilities given the wide operating temperature range.

Part Context

This component belongs to the LT4275 family of pin-compatible PD controllers. While the LT4275A supports higher LTPoE++ power levels up to 90W, the LT4275B variant is specifically optimized for IEEE 802.3at Type 2 applications. The family shares core control logic but differs in classification thresholds and supported power standards.

Replacement Considerations

LT4275A variants offer higher power capabilities but require different classification handling. LT4275C is suitable for lower power IEEE 802.3af applications. Cross-model substitution requires verifying package compatibility and ensuring the replacement supports the target PoE standard.