LT4295IUFD - IEEE 802.3bt PoE PD Controller | Analog Devices
Référence : LT4295IUFD ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $4.57 | $4,57 |
| 10 | $4.11 | $41,10 |
| 100 | $3.69 | $369,00 |
| 500 | $3.4 | $1 700,00 |
| 1 000 | $3.27 | $3 270,00 |
LT4295IUFD Présentation
A powered device interface controller is the circuitry that a PoE-powered endpoint (such as an IP camera, wireless access point, or network switch port device) uses to safely receive power over Ethernet cabling. It performs detection, classification, and inrush current limiting per the IEEE 802.3 standard, then hands off to a DC-DC converter stage that converts the 37V to 57V PoE input down to usable system rails. Within the power-management hierarchy, the LT4295 belongs to the PD controller plus switching-regulator-controller class of power over Ethernet ICs.
Key differentiating features include support for IEEE 802.3bt Type 3/Type 4 power levels via the T2P output, which indicates the number of classification events received during 802.3bt mutual identification and power negotiation. The LT4295 primarily targets single-signature PD topologies, eliminating the need for a second PD controller, and may also be deployed in dual-signature applications. The device supports both forward and flyback power supply topologies, and flyback operation supports No-Opto feedback, removing the optocoupler and its associated drift and aging concerns.
Technically, the LT4295 drives an external low-RDS(on) N-channel hot swap MOSFET for controlled inrush and overcurrent protection, and supports LT4320/LT4321 ideal diode bridges to extend end-to-end power delivery efficiency. Auxiliary input voltages can be accurately sensed with just a resistor divider connected to the AUX pin, enabling seamless auxiliary-power-to-PoE switchover in hybrid powered designs.
Typical applications include IEEE 802.3bt PoE+ powered IP surveillance cameras, 802.11ax wireless access points, PoE LED lighting drivers, and network intercom or building automation endpoints. The wide 60V rating provides margin over the 57V PoE bus.
Design consideration: because the LT4295 controls an external hot swap MOSFET, ensure the MOSFET SOA covers the bulk-capacitor inrush transient, and place the VCC decoupling capacitor close to the VCC and GND pins as the datasheet layout guidance specifies.
This page synthesizes distributor pricing, drop-in alternatives, design notes, and application guidance not found together in the manufacturer datasheet.
Alternatives de remplacement direct pour LT4295IUFD — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
LT4276IUFD#PBF
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
LT4276AIUFD#PBF
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
LT4295IUFD Valeurs maximales et caractéristiques électriques
| Fonction | IEEE 802.3af/at/bt PD interface controller with forward/flyback switching regulator controller |
| PoE Standards Supported | IEEE 802.3af (PoE), 802.3at (PoE+), 802.3bt |
| Canaux | 1 |
| Maximum Input Voltage Rating | 60 V |
| Switch/Clock Frequency | 214 kHz |
| Topology Support | Forward and Flyback (flyback supports No-Opto feedback) |
| Hot Swap MOSFET | External N-channel, low RDS(on) |
| Ideal Diode Bridge Support | LT4320 / LT4321 |
| Auxiliary Power Sensing | AUX pin, resistor divider |
| Classification Status Output | T2P output indicates number of 802.3bt classification events |
| Target Topology | Single-signature PD (dual-signature supported - contact ADI applications) |
| Operating Temperature Range (I grade) | -40C to +125C |
| Boîtier | 28-QFN (4x5 mm) (UFD) |
| Type de montage | Surface Mount |
| Statut RoHS | Compliant (#PBF - lead free) |
| 1ku List Price | USD 3.27 (as of 2026-10-19, Analog Devices product page) |
Guide de configuration des broches du LT4295IUFD 28-qfn (4x5 mm) (ufd)
Configuration des broches du LT4295IUFD (boîtier 28-qfn (4x5 mm) (ufd)). Ce composant de puissance comporte des bornes de grille, de drain et de source. Pour les boîtiers non polarisés, consultez la fiche technique du fabricant pour l'orientation exacte de la broche 1 et les détails de l'empreinte. Les applications courantes incluent la conception d'alimentations, la commande de moteurs et la commutation de charges.
Aucune donnée de brochage détaillée disponible pour LT4295IUFD.
Consultez la fiche technique pour la configuration complète des broches.
Applications typiques
LT4295IUFD convient pour 6 applications: IEEE 802.3bt IP Surveillance Cameras, 802.11ax Wireless Access Points, PoE LED Lighting Fixtures, Building Automation and Network Intercom Endpoints, 5G Small Cell and Outdoor Radio Units, VoIP Desk Phones and Conference Systems.
IEEE 802.3bt IP Surveillance Cameras
Multi-megapixel PTZ and thermal IP cameras draw well beyond the 25.5W of PoE+ when heaters, IR illuminators, and motorized lens assemblies run simultaneously, making IEEE 802.3bt Type 3/Type 4 power essential. The LT4295 fits because its T2P output reports the number of classification events received during 802.3bt mutual identification, letting the camera SoC know exactly how much power the PSE has granted - up to the 71.3W Type 4 PD level. Its 60V rating covers the full 37V-57V PoE range with margin, and the external hot swap MOSFET handles the inrush of large bulk capacitors typical in camera power trees. Implemented with a No-Opto flyback stage, the converter generates 12V/5V/3.3V camera rails without optocoupler drift. AUX-pin sensing via a resistor divider enables seamless switchover to a locally mounted auxiliary supply during PoE switch maintenance outages.
Recommandé
802.11ax Wireless Access Points
Enterprise 802.11ax access points with multi-radio MIMO front ends routinely exceed 25W of steady-state consumption, so ceiling deployments rely on IEEE 802.3bt power delivered over a single Cat-6 run. The LT4295 suits this use because it eliminates the need for a second PD controller in single-signature topologies, directly reducing BOM cost and board area in a densely packed AP enclosure, while still being deployable in dual-signature designs per ADI applications guidance. The 214 kHz switching clock allows a compact magnetics design for the forward converter generating the 5V radio rail, and the No-Opto flyback option removes an optocoupler that would otherwise age in the warm ceiling environment. Its AUX pin resistor-divider sensing cleanly prioritizes auxiliary DC jack power over PoE when both are present, and the T2P classification output lets firmware scale transmit power to the negotiated power budget.
Recommandé
PoE LED Lighting Fixtures
Connected LED luminaires for smart buildings increasingly use PoE as both the power and data medium, with fixtures drawing 30W-70W depending on lumen output and tunable-white channel count. The LT4295 is well matched: its 802.3bt classification interface negotiates the higher power classes, the 60V rating safely absorbs cable transients on long ceiling runs, and the flyback controller with No-Opto feedback produces a stable intermediate bus with fewer aging-prone components inside a sealed, thermally stressed luminaire housing. The external hot swap MOSFET keeps the PD front end efficient - designers pick a low-RDS(on) FET to cut conduction loss, and an LT4320/LT4321 ideal diode bridge on the rectifier side extends end-to-end power delivery efficiency, directly reducing luminaire thermal load. AUX sensing allows emergency-lighting battery packs to take over seamlessly when the PoE switch loses mains power.
Recommandé
Building Automation and Network Intercom Endpoints
Door stations, room controllers, and PoE intercom panels combine a network interface, an audio amplifier, and a display, typically landing in the 13W-51W range that spans 802.3at and 802.3bt Type 3. The LT4295 covers this entire span with one design: single-signature operation removes the second PD controller that dual-signature schemes would otherwise require, per the ADI datasheet, trimming cost in high-volume building products. The forward topology option suits the tightly regulated 5V logic rail, while No-Opto flyback suits isolated audio amplifier supplies. Its 214 kHz clock keeps transformer size small enough for slim door-station enclosures, and the external MOSFET approach lets designers trade RDS(on) for cost. The AUX pin enables hybrid designs where a local 24V doorbell transformer backs up PoE, with resistor-divider-only sensing accuracy sufficient for clean source arbitration.
Recommandé
5G Small Cell and Outdoor Radio Units
Outdoor 5G small cells and CPE radio units are installed on poles where running separate AC power is prohibitive, so they depend on IEEE 802.3bt at the top power classes, often 60W-71W at the PD. The LT4295 addresses this requirement directly: 802.3bt mutual identification via the T2P output tells the baseband processor the granted power so it can throttle RF output within budget. The 60V input rating plus an external hot swap MOSFET provide surge-tolerant front ends for lightning-exposed aerial cable runs, and pairing with an LT4321 ideal diode bridge cuts rectifier loss that matters at these power levels. The forward converter topology at 214 kHz supports the high-power, well-regulated PA supply rail. Wide -40C to +125C industrial (I grade) operation matches unconditioned outdoor enclosures that see full solar and winter extremes.
Recommandé
VoIP Desk Phones and Conference Systems
Enterprise VoIP phones and tabletop conference systems remain the classic PoE endpoint, with premium video bar models pushing past 25.5W into 802.3bt territory while legacy handsets stay at 802.3af. The LT4295 lets a single hardware platform serve all classes because the PD interface is compliant with 802.3af/at/bt simultaneously, and the T2P output reports classification events so firmware can enable feature sets according to negotiated power. The No-Opto flyback stage generates the isolated audio and logic rails with minimal component count, important in slim handset housings, and AUX-pin sensing supports hybrid wall-cubicle power arrangements. Inrush control through the external N-channel hot swap MOSFET meets the strict IEEE 802.3 present/missing signature and inrush behavior required when dozens of phones hot-plug into a shared PoE switch, and the industrial temperature grade covers conference-room equipment near heat sources.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour LT4295IUFD — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | LT4276IUFD#PBF | LT4276AIUFD#PBF |
|---|---|---|---|
| Package | 28-QFN (4x5 mm) (UFD) | 28-QFN (4x5 mm) (UFD) - same | 28-QFN (4x5 mm) (UFD) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices |
| PoE Standards | 802.3af / 802.3at / 802.3bt | 802.3af / 802.3at only | 802.3af / 802.3at only |
| T2P Classification Output | Yes (802.3bt classification event count) | No | No |
| Topology Support | Forward and Flyback (No-Opto) | Forward and Flyback (No-Opto) | Forward and Flyback (No-Opto) |
| Ideal Diode Bridge Support | LT4320 / LT4321 | LT4320 / LT4321 | LT4320 / LT4321 |
Principaux différenciateurs
- Full IEEE 802.3bt classification support (vs LT4276IUFD#PBF)
- Single-signature operation without a second PD controller (vs LT4276IUFD#PBF)
- No-Opto flyback feedback (vs LT4276IUFD#PBF)
Notes de conception
Per the LT4295 datasheet layout guidance, place the VCC decoupling capacitor as close as possible to the VCC pin (pin 21) and GND pin (pin 19), and keep all hot-swap and switching-loop components close to the LT4295 for optimal performance. Keep the gate-drive loop from the controller to the external hot swap MOSFET short and wide to minimize parasitic inductance, and star-connect the controller ground to the power ground at a single point to prevent switching currents from corrupting the detection and classification comparators.
Because the LT4295 drives an external, low RDS(on) N-channel hot swap MOSFET, the designer owns the inrush and SOA analysis: size the bulk capacitor so that the MOSFET current-limit foldback keeps the die inside its safe operating area during IEEE 802.3 inrush (estimated: with 100uF bulk and ADI-recommended inrush targets, verify I^2*t against the MOSFET SOA curve). Pair with LT4320/LT4321 ideal diode bridges to cut rectifier conduction loss and improve end-to-end delivery efficiency at 802.3bt power levels.
The LT4295 primarily targets single-signature PD topologies and the datasheet limits its IEEE 802.3 standard descriptions to single-signature PDs. If your application is dual-signature 802.3bt (four-pair with independent signatures), contact Analog Devices Applications before committing the design - classification behavior differs and an unqualified dual-signature layout can fail PSE interoperability testing. Also remember the T2P output only reports classification event count during 802.3bt negotiation; it is not a power-good indicator.
Use the AUX pin with a simple resistor divider for auxiliary input sensing - the datasheet states auxiliary voltages can be accurately sensed with just a divider, but divider current should be kept low to limit standing power drain in PoE budget-constrained designs. Keep the 214 kHz switching node copper area compact and shield the classification-signature network from the flyback/forward switching loop to avoid corrupting the detection signature that the PSE measures.
Informations de conformité
#PBF ordering code indicates lead-free, RoHS-compliant packaging per DigiKey/Mouser listings. REACH, halogen-free, and conflict-minerals declarations were not present in the provided data - download the material declaration from the Analog Devices product page.
