LT4276AIUFD - LTPoE++/PoE+/PoE PD Forward/Flyback Controller | Analog Devices
Teilenummer: LT4276AIUFD ✓ Aktiv| Menge | Stückpreis | Gesamt |
|---|---|---|
| 1 | $4.62 | $4,62 |
| 10 | $4.1 | $41,00 |
| 100 | $3.55 | $355,00 |
| 500 | $3.05 | $1.525,00 |
| 1.000 | $2.47 | $2.470,00 |
| 2.500 | $2.28 | $5.700,00 |
LT4276AIUFD Übersicht
A Power-over-Ethernet (PoE) Powered Device controller is a specialized power management IC that negotiates power delivery from an Ethernet switch or midspan injector and converts the 48V PoE rail into the regulated voltages required by the PD load. PoE controllers belong to the broader class of Power Management ICs (PMICs), specifically within the PMIC > Power Over Ethernet (PoE) Controllers family. They sit between the RJ45 magnetics and the downstream DC-DC converter, implementing detection, classification, inrush limiting, hot-swap FET control, and isolation handoff to a switching regulator.
Key features of the LT4276A include: integrated 100V Hot Swap FET, support for legacy high-power Mode A and Mode B operation, programmable inrush current, soft-start, and an auxiliary supply input that allows automatic takeover from a local 24V/48V supply. The auxiliary input also enables operation without the PD interface (wall-adapter mode). The forward topology is preferred for higher output power (>40W) because it transfers energy efficiently through a single primary-side switch, while the flyback topology suits lower-power PDs requiring multiple output rails.
Typical applications include high-power 802.3at/LTPoE++ powered devices such as 802.11ax Wi-Fi 6/7 access points, PTZ surveillance cameras, industrial PoE lighting, 5G small-cell radios, and digital signage. The auxiliary input makes it well suited to enterprise access points that must remain operational during PoE outages via a wall adapter. According to the manufacturer datasheet, the LT4276 family is pin-for-pin compatible, allowing designers to migrate between A/B/C variants and PoE+/LTPoE++ modes without PCB rework.
A critical design consideration is thermal management at 90W LTPoE++ power levels: the 28-QFN (4x5) package requires adequate copper pours on the PCB to dissipate the Hot Swap FET losses. Designers should also size the TVS protection on the Ethernet lines per IEEE 802.3 to withstand 6 kV surge events. The auxiliary supply input must be back-biased with a Schottky diode to prevent reverse conduction into the wall adapter during PoE operation.
This page synthesizes distributor pricing, pin-for-pin drop-in alternatives from the LT4276 family, and practical design notes not found in the manufacturer datasheet.
Drop-in-Alternativen für LT4276AIUFD – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit LT4276AIUFD (gleiche Bauform und Footprint) – abweichend in MSL Level, Operating Temperature, Package, RoHS Status.
Schnellvergleichstool – Wählen Sie Alternativbauteile für den Direktvergleich:
LT4276AHUFD#PBF
✅ Drop-In✓ Auf Lager
$4.58 / Stück
Datenblatt ansehen →LT4276BHUFD#PBF
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
LT4276AIUFD#TRPBF
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
LT4276AIUFD Technische Daten
| Product Type | Powered Device (PD) Controller |
| PoE Standard | IEEE 802.3af/at, LTPoE++ |
| LTPoE++ Power Levels | 38.7W / 52.7W / 70W / 90W |
| PoE+ Power | 25.5W |
| PoE Power | 12.95W |
| Number of Channels | 1 |
| Topology Support | Forward / Flyback |
| Auxiliary Supply Support | Yes (auto takeover) |
| Integrated Hot Swap FET | Yes, 100V |
| Betriebstemperatur | -40C to +85C |
| Gehäuse | 28-QFN (4x5 mm) |
| Montageart | Surface Mount |
| MSL-Level | 1 (unlimited) |
| RoHS-Status | Compliant (#PBF suffix) |
| Lead-Free | Yes |
| Halogenfrei | Yes |
| 1ku List Price (Starting) | $2.47 USD |
LT4276AIUFD Pin-Konfiguration
| Pin 1 | AUX — Auxiliary supply input for wall-adapter takeover |
| Pin 2 | NC — Not connected (per datasheet) |
| Pin 3 | VCC — Internal 5V regulator bypass |
| Pin 4 | VEE — Negative supply / gate return |
| Pin 5 | GATE — Hot Swap FET gate drive |
| Pin 6 | DRAIN — Hot Swap FET drain sense |
| Pin 7 | SOURCE — Hot Swap FET source / RTN |
| Pin 8 | VPORTP — Positive PoE port input |
| Pin 9 | VPORTN — Negative PoE port input |
| Pin 10 | RCLASS — Classification resistor |
| Pin 11 | RDET — Detection resistor |
| Pin 12 | SIG — Signature / MPS control |
| Pin 13 | T2P — Type 2 PSE indicator |
| Pin 14 | PG — Power good output |
| Pin 15 | SS — Soft-start capacitor |
| Pin 16 | COMP — Compensation network |
| Pin 17 | FB — Feedback voltage input |
| Pin 18 | REF — Reference voltage bypass |
| Pin 19 | RT — Switching frequency setting resistor |
| Pin 20 | SYNC — Synchronization input/output |
| Pin 21 | PWM — PWM gate drive output |
| Pin 22 | SENSE — Current sense input |
| Pin 23 | VIN — Converter input voltage |
| Pin 24 | AUXON — Auxiliary supply enable output |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | GND — Ground |
| Pin 28 | EP — Exposed pad - thermal and ground |
Typische Anwendungen
LT4276AIUFD ist geeignet für 6 Anwendungs: 802.11ax/802.11be Wi-Fi 6/7 Access Points, PTZ Surveillance Cameras, 5G Small-Cell Radios, Industrial PoE Lighting Controllers, Digital Signage and Interactive Kiosks, IoT PoE Sensor Hubs and Edge Gateways.
802.11ax/802.11be Wi-Fi 6/7 Access Points
The LT4276AIUFD's LTPoE++ support up to 90W is ideal for high-performance Wi-Fi 6E and Wi-Fi 7 enterprise access points that require more power than standard PoE+ delivers. These APs typically need 35-60W to drive multi-radio MIMO chains, internal antennas, and PoE-output ports for downstream devices. The integrated 100V Hot Swap FET eliminates external MOSFETs, reducing PCB area in compact ceiling-mount enclosures. Auxiliary supply input supports wall-adapter failover for mission-critical enterprise deployments. Compared to discrete PoE designs, the single-IC approach cuts BOM by 30-40 parts and ensures full IEEE 802.3af/at compliance with the additional LTPoE++ 90W negotiation per the Analog Devices datasheet.
Empfohlen
PTZ Surveillance Cameras
Outdoor and indoor PTZ (pan-tilt-zoom) cameras with heaters, IR illuminators, and motorized lens assemblies need 25-70W peak power - well within the LT4276AIUFD's LTPoE++ capability. The IC's auxiliary supply input is particularly valuable for installations where both PoE and a local 24VAC supply are present, automatically selecting the higher-voltage source. Forward or flyback topology flexibility allows designers to choose transformer style based on whether they need a single 12V rail or multiple rails for camera DSP, motor drivers, and heater control. The integrated Hot Swap FET and signature detection remove the need for separate protection circuitry, critical for outdoor cameras exposed to 6kV Ethernet surge events per IEEE 802.3.
Empfohlen
5G Small-Cell Radios
5G millimeter-wave and sub-6 GHz small-cell radios consume 40-80W peak power and benefit from the LT4276AIUFD's LTPoE++ 70W/90W classification levels. The IC's synchronous forward converter topology with auxiliary supply allows the radio to remain operational during PoE infrastructure outages - essential for cellular coverage reliability. The 28-QFN (4x5) package with exposed thermal pad supports sustained high-power operation when mounted on adequate PCB copper area. The forward topology's lower RMS currents versus flyback is preferred at these power levels for higher converter efficiency and reduced transformer heating. The Analog Devices datasheet specifies the LT4276A for receiving 38.7W, 52.7W, 70W, or 90W at the PD RJ45 connector.
Empfohlen
Industrial PoE Lighting Controllers
PoE-powered industrial lighting systems for warehouses, parking structures, and smart-city deployments commonly use 60-90W per fixture, directly matching the LT4276AIUFD's LTPoE++ 70W/90W power levels. Each fixture can be individually addressable and dimmable over the Ethernet cable, eliminating high-voltage AC wiring in ceilings. The IC's auxiliary supply input allows hybrid installations where emergency lighting runs on local battery-backed 48V DC, with automatic failover. Forward or flyback topology selection depends on whether the LED driver needs a single high-current string or multiple parallel strings. The integrated Hot Swap FET provides protection against inrush currents when many fixtures are simultaneously powered up.
Empfohlen
Digital Signage and Interactive Kiosks
Large-format digital signage displays, interactive kiosks, and wayfinding terminals typically require 40-60W for the LCD backlight, compute module, and touch interface - well within the LT4276AIUFD's LTPoE++ capability. The single-Cable Ethernet deployment simplifies installation in retail, transit, and corporate environments where running separate AC power is cost-prohibitive. The auxiliary supply input supports battery-backed operation for emergency information displays. The IC's ability to negotiate LTPoE++ 52.7W or 70W levels ensures sufficient headroom even at peak backlight brightness. Compared to standard PoE+ (25.5W), LTPoE++ doubles available power, enabling larger and brighter displays per the Analog Devices datasheet classification table.
Empfohlen
IoT PoE Sensor Hubs and Edge Gateways
Industrial IoT edge gateways aggregating multiple sensor protocols (Modbus, IO-Link, RS-485) over a single PoE cable benefit from the LT4276AIUFD's LTPoE++ support for powering both the gateway compute and downstream sensor networks. Power levels up to 90W allow the gateway to include LoRaWAN or cellular backhaul radios alongside wired sensor aggregation. The auxiliary supply input enables solar-battery-backed operation for remote deployments. The IC's flyback topology option suits multi-rail designs where the gateway needs 3.3V for digital, 12V for analog, and 24V for industrial fieldbus. The 28-QFN (4x5) footprint and industrial temperature grade (-40C to +85C) match outdoor and factory-floor environmental requirements.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für LT4276AIUFD – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | LT4276AHUFD#PBF | LT4276BHUFD#PBF | LT4276AIUFD#TRPBF |
|---|---|---|---|---|
| Package | 28-QFN (4x5) | 28-QFN (4x5) - same | 28-QFN (4x5) - same | 28-QFN (4x5) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| PoE Standard | 802.3af/at, LTPoE++ | 802.3af/at, LTPoE++ | 802.3af/at (industrial efficiency) | 802.3af/at, LTPoE++ |
| Maximum PD Power | 90W (LTPoE++) | 90W (LTPoE++) | 25.5W (PoE+) | 90W (LTPoE++) |
| Topology Support | Forward / Flyback | Forward / Flyback | Forward / Flyback | Forward / Flyback |
| Auxiliary Supply Input | Yes | Yes | Yes | Yes |
| Integrated Hot Swap FET | 100V | 100V | 100V | 100V |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Wichtigste Unterscheidungsmerkmale
- Highest LTPoE++ power support at 90W (vs. LT4276BHUFD#PBF)
- Pin-for-pin drop-in within the same 28-QFN family (vs. LT4276AHUFD#PBF)
- Integrated auxiliary supply input with auto-takeover (vs. Standard PoE+ controllers)
Designhinweise
At 90W LTPoE++ input power and typical 90% converter efficiency, the LT4276AIUFD must dissipate approximately 6-9W of loss in the integrated Hot Swap FET plus the switching converter. The 28-QFN (4x5) package exposes a thermal pad (pin 28) that MUST be soldered to a continuous ground plane with at least 25x25 mm of 2 oz copper pour to maintain junction temperature below 125C. Without adequate thermal management, the device will trigger internal thermal shutdown at sustained 90W loads in enclosed fixtures. Estimated thermal resistance theta_JA is approximately 35 C/W on a 4-layer JEDEC test board, resulting in a ~40C temperature rise at 5W dissipation.
Place the RT resistor and SS capacitor within 5 mm of their respective pins to minimize noise pickup on the high-impedance oscillator and soft-start nodes. Route the high-current Hot Swap return path directly to the VPORTN input via a wide trace - do not share this path with low-level analog ground returns. The exposed thermal pad requires multiple thermal vias (0.3 mm drill, 1 mm pitch) connecting the top copper to inner ground planes for optimal heat extraction. Keep switching node traces (PWM, gate driver) short and away from the feedback (FB) and compensation (COMP) traces to prevent noise injection into the regulation loop.
Do not omit the TVS protection on VPORTP/VPORTN lines - IEEE 802.3 mandates 6 kV surge withstand capability and the integrated Hot Swap FET alone cannot survive this without external protection. Use a bidirectional TVS rated for 58V working voltage (e.g., SMAJ58CA). When using the auxiliary supply input, place a Schottky diode between AUX and VCC to prevent reverse conduction into the wall adapter during PoE operation. The classification resistor value must exactly match the desired power class - using 802.3at values (RCLASS=30.9 ohm for Class 4) will not engage LTPoE++ 70W/90W modes. Always verify T2P (Type 2 PSE indicator) state before assuming high-power availability from the PSE.
Compliance-Informationen
RoHS compliant per #PBF suffix nomenclature. Industrial temperature grade (-40C to +85C) but not AEC-Q100 qualified - not intended for safety-critical automotive applications. Compliant with IEEE 802.3af/at PoE standards and LTPoE++ proprietary classification scheme.
