LT4275BIDD#PBF

Overview

The LT4275BIDD#PBF is a Powered Device (PD) controller compliant with IEEE 802.3at Type 2 standards, supporting up to 25.5W of power delivery. It operates within an input voltage range of 9V to 60V and utilizes an external N-channel MOSFET topology managed by an internal charge pump. The device is housed in a 10-lead DFN package measuring 3mm x 3mm with an exposed pad. It features integrated signature resistance, undervoltage lockout, thermal protection, and a power-good output. The component supports auxiliary power inputs for low-voltage operation and includes drive capabilities for optocouplers to indicate Power Sourcing Equipment (PSE) power levels.

Feature Summary

• Supports IEEE 802.3at PoE+ classification and control for powered devices
• Utilizes external N-channel MOSFET driven by internal charge pump for high efficiency
• Includes integrated signature resistor and programmable auxiliary power support
• Provides optical coupler drive outputs to signal connected PSE power levels

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 IDD#PBF confirms the 10-lead DFN(3x3) surface-mount package and lead-free composition. Confirm that the B variant strictly adheres to IEEE 802.3at Type 2 specifications, as opposed to the A variant which supports LTPoE++. Ensure the design accounts for the external N-channel MOSFET requirement, as the controller does not integrate internal switches. Validate auxiliary input configurations if utilizing non-standard low-voltage PoE modes.

Selection Notes

Select this component when designing PDs requiring IEEE 802.3at compliance with up to 25.5W power draw. The LT4275B differs from the LT4275A, which supports higher proprietary LTPoE++ power levels. Consider the 3mm x 3mm DFN footprint for space-constrained layouts. The controller requires an external N-channel MOSFET; ensure gate drive compatibility. Auxiliary pin functionality allows for flexible power management strategies in mixed-source environments.

Part Context

The LT4275 series comprises pin-compatible controllers for IEEE 802.3 and LTPoE++ applications. The LT4275B specifically targets Type 2 PoE+ devices, while the LT4275A handles higher power LTPoE++ classifications. The family eliminates the need for costly P-channel MOSFETs through internal charge pump technology. This architecture maximizes power transfer efficiency and simplifies thermal design for compact powered device implementations.

Replacement Considerations

LT4275AIDD#PBF offers broader LTPoE++ support but shares pin compatibility. LT4275CIDD#PBF is suitable for lower-power IEEE 802.3af Type 1 applications. Cross-referencing requires verifying the specific power class requirements against the B variant's Type 2 limitations.