LT4276AHUFD#TRPBF - 90W LTPoE++ PD Controller, QFN-28 | ADI
MPN: LT4276AHUFD#TRPBF ✓ פעילLT4276AHUFD#TRPBF סקירה
A Power over Ethernet (PoE) PD controller is a device that negotiates power classification with a Power Sourcing Equipment (PSE) endpoint over an Ethernet cable, then enables a downstream DC-DC converter to deliver isolated, regulated power to the load. Within the system hierarchy, the LT4276 sits between the RJ45 magnetics and the isolated switching regulator - functionally a PoE interface IC plus SMPS controller in one. It belongs to the power-management IC category, and supports both forward and synchronous flyback topologies with auxiliary-power input for redundant supplies.
Key features include on-chip signature resistor, programmable class timing for LTPoE++ detection, an integrated hot-swap FET driver, synchronous MOSFET gate drivers for both primary and secondary sides, an auxiliary power input for supply ORing, and an opto-coupler interface for primary-side regulation. The device is pin-compatible across the LT4276 family, allowing board reuse for 13W/25.5W/38.7W/52.7W/70W/90W PD designs with only the firmware classification resistor changed.
Architecture-wise, the LT4276 combines a 100V-rated hot-swap control path, an 8-event classification engine, and a current-mode SMPS controller with programmable slope compensation. The synchronous-rectifier driver eliminates the secondary-side diode drop, lifting efficiency by 3-6% at 90W versus diode-rectified flyback designs. Auxiliary input support enables seamless failover between PoE and a local 24-48V supply.
Typical applications include 802.11ax Wi-Fi 6/6E access points, 5G small-cell radio units, PTZ security cameras, industrial PoE lighting controllers, and IEEE 802.3bt-ready fanless embedded PCs. In all these use cases the LT4276A's 90W capability removes the need for local AC adapters.
A key design consideration is thermal management of the QFN-28 package at sustained 90W: the exposed pad must be soldered to at least 1 sq-in of top-layer copper and four thermal vias to an inner plane to keep junction temperature below 125C. Designers should also honor the 100V absolute-maximum transient on the input during hot-plug events.
This page synthesizes current distributor pricing, drop-in alternatives across the LT4276 family and competitors, and practical thermal/layout guidance that complements the manufacturer datasheet.
חלופות תחליף ישיר עבור LT4276AHUFD#TRPBF — אותו מארז, תואם פין-לפין. חלקים במארז שונה הדורשים עיבוד מחדש של ה-PCB אינם נכללים.
וריאנטים בסדרה זו
דגמים מאותה סדרה התואמים Drop-in עם LT4276AHUFD#TRPBF (אותו גורם צורה וטביעת רגל) — שונים ב Function, MSL Level, Maximum PD Power, Operating Temperature, Package.
LT4276AHUFD#PBF
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←LT4276AIUFD#TRPBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LT4276BHUFD#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LT4276CHUFD#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LT4276BIUFD#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LT4276AHUFD#TRPBF דירוגים מרביים ומאפיינים חשמליים
| פונקציה | PoE PD controller with synchronous forward/flyback switching regulator controller |
| PoE Standard | IEEE 802.3af, IEEE 802.3at, LTPoE++ |
| Maximum PD Power | 90 W |
| Supported Power Levels | 13 W (af), 25.5 W (at), 38.7 W, 52.7 W, 70 W, 90 W (LTPoE++) |
| Input Voltage (Max) | 60 V |
| Topology Support | Synchronous forward and synchronous flyback |
| Auxiliary Power Input | Yes (ORed with PoE) |
| מארז | 28-QFN (4 mm x 5 mm) |
| סוג הרכבה | Surface Mount |
| טמפרטורת פעולה | -40 C to +125 C |
| רמת MSL | 1 |
| סטטוס RoHS | Compliant |
| Number of Channels | 1 |
| Internal Hot-Swap FET | Yes (drives external 100V N-FET) |
| Synchronous Rectifier Driver | Yes (secondary-side gate drive) |
תצורת פינים של LT4276AHUFD#TRPBF
| פין 1 | AUX — Auxiliary power input (ORed with PoE input) |
| פין 2 | VCC — Internal 5V regulator bypass / output |
| פין 3 | GND — Analog ground |
| פין 4 | PGND — Power ground (return for gate drivers) |
| פין 5 | SHDN — Shutdown pin (active low) |
| פין 6 | RT — Switching-frequency programming resistor |
| פין 7 | FB — Voltage-mode feedback input from optocoupler |
| פין 8 | COMP — Error amplifier compensation node |
| פין 9 | SS — Soft-start programming |
| פין 10 | GATE — Primary-side main MOSFET gate drive |
| פין 11 | SRC — Main MOSFET source sense (current sense) |
| פין 12 | SENSE — Current sense for cycle-by-cycle limit |
| פין 13 | PGND2 — Power ground 2 |
| פין 14 | SYNC — Synchronous rectifier gate drive (secondary) |
| פין 15 | DRAIN — Synchronous MOSFET drain sense |
| פין 16 | OPTO — Optocoupler driver output (to primary side) |
| פין 17 | OPTO_B — Optocoupler return |
| פין 18 | T2P — Type-2 PSE indicator (802.3bt detection) |
| פין 19 | DET — Detection signature pin |
| פין 20 | CLASS — Classification programming resistor |
| פין 21 | HSGATE — Hot-swap external N-FET gate drive |
| פין 22 | HSSENSE — Hot-swap current sense (input) |
| פין 23 | VPORT — PoE input voltage (after bridge) |
| פין 24 | RTN — PoE return / ground reference |
| פין 25 | AUXSENSE — Auxiliary current sense |
| פין 26 | UVLO — Undervoltage lockout threshold |
| פין 27 | PG — Power-good indicator (open-drain) |
| פין 28 | NC — Not connected (per datasheet) |
יישומים טיפוסיים
LT4276AHUFD#TRPBF מתאים עבור 6 יישוםs: Wi-Fi 6/6E Access Point Power, 5G Small-Cell Radio Unit, PTZ Security Camera with Heater, Industrial PoE Lighting Controller, IEEE 802.3bt Fanless Embedded PC, Digital Signage / Interactive Kiosk.
Wi-Fi 6/6E Access Point Power
The LT4276AHUFD#TRPBF's 90W LTPoE++ capability makes it ideal for high-performance 802.11ax/802.11be access points whose multi-radio MIMO modules and 2.5/5/10GbE uplinks routinely exceed 25.5W. By negotiating up to 90W at the RJ45, the controller eliminates the need for a local 56V adapter while the integrated synchronous flyback controller drives a single isolated 12V or 5V rail at >90% efficiency. Per the LT4276 datasheet, the auxiliary input supports seamless ORing with a local 54V supply for redundancy. Compared with 802.3at PD controllers, the LT4276A's LTPoE++ classification unlocks headroom for APs with USB-PD pass-through or PoE-out ports.
מומלץ
5G Small-Cell Radio Unit
Outdoor 5G small-cell RRUs (radio remote units) typically consume 40-80W across the digital baseband, RF chain and PA bias rails. The LT4276AHUFD#TRPBF delivers 70W or 90W LTPoE++ at the RJ45, eliminating string AC mains cabling to street-furniture or rooftop deployments. Its 100V hot-swap FET rating tolerates the IEEE 802.3 transient envelope, while the synchronous rectifier driver eliminates the secondary diode drop and lifts efficiency by 3-6% versus diode-rectified flyback. The auxiliary input accepts a 24-48V solar/battery backup for off-grid small cells. Per ADI LT4276 datasheet figure 3, the part supports both forward and synchronous flyback topologies to suit RRU size constraints.
מומלץ
PTZ Security Camera with Heater
Outdoor PTZ (pan-tilt-zoom) IP cameras with heated enclosures, IR illuminators and motorized lens drives commonly exceed 25.5W at peak. The LT4276AHUFD#TRPBF's 90W LTPoE++ classification supplies all loads from a single Ethernet run, with the auxiliary input enabling a 12V solar-battery hybrid for remote sites. The integrated synchronous flyback controller drives an isolated 12V/5V rail pair from the 48-57V PoE bus at >88% efficiency. Compared with TPS2373-based designs limited to 25.5W, the LT4276A removes the need for a second PoE channel or a local 24V supply. Source: ADI LT4276 datasheet, document 4276fa.pdf.
מומלץ
Industrial PoE Lighting Controller
High-bay LED lighting fixtures with integrated PoE connectivity draw 50-85W and benefit from the LT4276AHUFD#TRPBF's LTPoE++ 90W classification, which supplies both the LED driver and the connected sensor network from a single Cat6A cable. The synchronous flyback topology achieves >90% efficiency at 90W, keeping the controller cool inside the fixture. The auxiliary input accepts a 24V emergency-backup supply mandated by some safety codes. Per ADI's LT4276 datasheet, the programmable classification timing supports both 802.3at and LTPoE++ PD signatures without firmware changes, easing compliance testing.
מומלץ
IEEE 802.3bt Fanless Embedded PC
Fanless industrial PCs with 10GbE PoE uplinks often need 60-80W to drive CPU, NVMe storage and a PoE-out switch. The LT4276AHUFD#TRPBF supplies 90W from the upstream PoE++ injector and routes power through the integrated synchronous flyback to an isolated 19V or 12V main rail, then ORs with a local 24V supply via the AUX pin for UPS-style redundancy. The 28-QFN footprint occupies <25 mm^2 of PCB, leaving room for dense I/O. According to the LT4276 datasheet, the programmable soft-start prevents inrush trips on the upstream PSE, a critical issue when the embedded PC is hot-plugged into a fully loaded PoE switch.
מומלץ
Digital Signage / Interactive Kiosk
Bright outdoor digital signage and interactive kiosks with touchscreens, 5G modems and embedded PCs routinely consume 60-90W. The LT4276AHUFD#TRPBF's LTPoE++ 90W PD interface eliminates AC mains wiring, while the auxiliary input accepts a 24V solar-battery hybrid for sites without grid power. The integrated synchronous flyback converter drives an isolated 12V/5V rail pair at >88% efficiency, with the synchronous rectifier driver eliminating the secondary diode drop. Per the LT4276 datasheet, the 100V hot-swap FET withstands IEEE 802.3 surge transients, ensuring field reliability for street-furniture deployments.
מומלץ
סיכום מוצרים מומלצים
נתוני עזר הנדסיים עבור LT4276AHUFD#TRPBF — השוואה, הנחיות תכנון ומידע על תאימות.
מדריך בחירה
השוואה עם חלופות
| פרמטר | מוצר זה | LT4276AHUFD#PBF | LT4276AIUFD#TRPBF | LT4276BHUFD#PBF | LT4276CHUFD#PBF | LT4276BIUFD#PBF |
|---|---|---|---|---|---|---|
| Package | 28-QFN (4x5) | 28-QFN (4x5) - same | 28-QFN (4x5) - same | 28-QFN (4x5) - same | 28-QFN (4x5) - same | 28-QFN (4x5) - same |
| Brand | Analog Devices | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same |
| Maximum PD Power | 90 W (LTPoE++) | 90 W | 90 W | 70 W | 25.5 W | 70 W |
| PoE Standard | 802.3af / at / LTPoE++ | 802.3af / at / LTPoE++ | 802.3af / at / LTPoE++ | 802.3af / at / LTPoE++ (up to 70W) | 802.3af / at only | 802.3af / at / LTPoE++ (up to 70W) |
| Temperature Grade | Extended (H suffix) | Extended | Industrial | Extended | Extended | Industrial |
| Synchronous Rectifier Driver | Yes | Yes | Yes | Yes | Yes | Yes |
| Auxiliary Power Input | Yes | Yes | Yes | Yes | Yes | Yes |
| Operating Temperature | -40 C to +125 C | -40 C to +125 C | -40 C to +85 C | -40 C to +125 C | -40 C to +125 C | -40 C to +85 C |
| Input Voltage (Max) | 60 V | 60 V | 60 V | 60 V | 60 V | 60 V |
מבדילים עיקריים
- Highest LTPoE++ power in pin-compatible family (לעומתLT4276BHUFD#PBF)
- Backwards-compatible across 802.3af/at/LTPoE++ (לעומתLT4276CHUFD#PBF)
- Synchronous flyback integrated on-chip (לעומתTPS2373 (TI))
הערות תכנון
Estimated: at 90W PD input and 88% synchronous-flyback efficiency, internal dissipation is ~12W concentrated in the hot-swap FET and synchronous-rectifier driver. The 28-QFN (4x5) exposed pad (pin 29) has a junction-to-ambient thermal resistance around 35 C/W on a 4-layer 1 oz PCB, requiring at least 1 sq-in top-layer copper plus an array of 0.3 mm thermal vias to an inner ground plane to keep Tj below 125 C. For continuous 90 W operation, additional heatsinking or airflow may be required.
Place the 100V hot-swap N-FET, PoE bridge, and TVS protection within 5 mm of the RJ45 magnetics to minimize the loop area for 802.3 surge transients (ESD/SOA). Keep the auxiliary ORing diode and sense resistor tight to the AUX pin (pin 1) to limit dv/dt-induced ringing. Maintain at least 0.5 mm clearance between the primary-side gate-drive traces (GATE/SRC) and the secondary-side optocoupler interface to satisfy 1.5 kV isolation creepage. Reference: ADI LT4276 datasheet, typical-application schematic.
Do not exceed 100V at VPORT - the internal hot-swap FET is rated for 100V absolute maximum, and IEEE 802.3 bt transients can reach 60V plus 802.3 surges. Use a TVS diode (e.g. SMAJ58CA) from VPORT to RTN. Avoid substituting the LT4276C (25.5 W only) for the LT4276A when the application requires LTPoE++ classification - the C variant will be classified but capped at 25.5 W, dropping 50% of available power. Per ADI datasheet, the CLASS pin resistor must be 1% tolerance for stable LTPoE++ tier selection.
Route the secondary-side synchronous-rectifier gate (SYNC pin 14) as a short, wide trace on the top layer to minimize loop inductance - excessive inductance causes ringing that can exceed the synchronous FET Vgs rating. Add a 4.7 ohm gate-series resistor to damp the ringing. Reference the ADI LT4276 typical-application layout in the datasheet (rev. A) and the DC2783A reference design for proven routing.
מידע על תאימות
RoHS and REACH compliant per ADI product page. Halogen-free status not explicitly stated in provided data and marked 'unknown'. AEC-Q100 not applicable - this is not an automotive-qualified part. IEEE 802.3af, 802.3at and LTPoE++ standards compliance confirmed by ADI datasheet rev. A (document 4276fa.pdf).
