Features and Benefits
- IEEE 802.3af/at/bt Powered Device (PD) with Forward/Flyback Controller
- Supports Up to 71.3W 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
The LT4295 is an IEEE 802.3af/at/bt-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 RDS(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.
- High Power Wireless Data Systems
- Outdoor Security Camera Equipment
- Commercial and Public Information Displays
- High Temperature Applications
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (4)
Demonstration Circuit 2476A is an Ethernet Alliance™ Gen 2 PoE certified IEEE 802.3bt compliant power over ethernet (PoE) powered device (PD). It features the LT4295 PD interface and switching regulator controller and the LT4321 PoE ideal diode bridge controller. It features the LT4295 PD interface and switching regulator controller and the LT4321 PoE ideal diode bridge controller.
The LT4295 provides IEEE 802.3af (PoE, Type 1), IEEE 802.3at (PoE+, Type 2), and IEEE 802.3bt (PoE++, Type 3 and 4) compliant interfacing and power supply control. It utilizes an external, low RDS(on) (30mΩ typical) N-channel FET for the hot swap function to improve efficiency. The LT4295 controls a DC/DC converter that utilizes a highly efficient flyback topology with synchronous rectification.
The LT4321 controls eight low RDS(on) (30mΩ typical) N-channel FETs to further improve end-to-end power delivery efficiency and ease thermal design. This solution replaces the eight diodes typically found in a passive PoE rectifier bridge.
The DC2476A-A accepts up to 71.3W of delivered power from a power sourcing equipment (PSE) via the RJ45 connector (J1) or a local 48V DC power supply using the auxiliary supply input. When both supplies are connected, the auxiliary supply input has priority over the PoE input. The DC2476A-A supplies a 24V output at up to 2.7A as a Class 8 (71.3W) PD and up to 2.4A as a Class 7 (62W) PD application.
Demonstration circuit 2539A is an IEEE802.3bt (Draft 2.1) compliant Power over Ethernet (PoE) Powered Device (PD). It features the LT4295 PD interface and switching regulator controller and the LT4321 PoE ideal diode bridge controller.
Demonstration circuit 2584A is an IEEE 802.3bt (Draft 2.1) compliant Power over Ethernet (PoE) Powered Device (PD). It features the LT4295 PD interface and switching regulator controller and the LT4321 PoE ideal diode bridge controller.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Support & Discussions
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.