Features

• IEEE 802.3af/at/bt(Draft 2.0) Powered Device (PD) with Forward/Flyback Controller
• Supports Up to 71 Watt PDs
• 5-Event Classification Sensing
• Superior Surge Protection (100V Absolute Maximum)
• Wide Junction Temperature Range (–40°C to 125°C)
• >94% End-to-End Efficiency with LT4321 Ideal Bridge
• External Hot Swap N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency
• No-Opto Flyback Operation
• Auxiliary Power Support as Low as 9V
• Easy Migration of LTPoE++® PDs to IEEE 802.3bt PDs
• Pin Compatible with LT4276A/B/C
• 28-Lead 4mm × 5mm QFN Package

Typical Application

Description

The LT4295 is an IEEE 802.3af/at/bt(Draft 2.0)-compliant powered device (PD) interface controller with a switching regulator controller. The T2P output indicates the number of classification events received during IEEE 802.3bt-compliant mutual identification and negotiation of available power.

The LT4295 supports both forward and flyback power supply topologies. The flyback topology supports No-Opto feedback. Auxiliary input voltages can be accurately sensed with just a resistor divider connected to the AUX pin.

The LT4295 utilizes an external, low R DS(on) N-channel hot swap MOSFET and supports the LT4320/LT4321 ideal diode bridges, to extend the end-to-end power delivery efficiency and eliminate costly heat sinks.

The LT4295 also includes an on-chip detection signature resistor, thermal protection, slope compensation, and many user configurable settings including classification signature, inrush current, switcher frequency, gate drive delay, soft-start, and load compensation.