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Analog Devices Inc. LT4294IDD#PBF
- Part No.:
- LT4294IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT4294IDD#PBF.pdf
- Description:
- IC POE CNTRL 1 CHANNEL 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:266
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Product details
Overview
LT4294IDD#PBF from Analog Devices is an IEEE 802.3af/at/bt-compliant single-signature powered device (PD) interface controller in a 10-lead 3mm × 3mm DFN package, supporting up to 71.3W input power, featuring 5-event classification sensing, integrated signature resistor (24.4 kΩ), and auxiliary power override down to 9V. It controls an external N-channel hot-swap MOSFET for high-efficiency PoE power delivery in outdoor security cameras and commercial displays.
For engineers reviewing the LT4294IDD#PBF datasheet, LT4294IDD#PBF pinout, LT4294IDD#PBF application, or LT4294IDD#PBF equivalent, this page delivers verified technical context, exact pin functions, real-world classification behavior, T2P-encoded power negotiation logic, and validated alternatives for IEEE 802.3bt PD designs requiring stable 71.3W operation with thermal protection and auxiliary supply fallback.
Technical Context
The LT4294IDD#PBF implements IEEE 802.3bt single-signature PD detection and classification using a precision 24.4 kΩ temperature-compensated signature resistor and dual-class resistors (RCLASS/RCLASS++) to configure Classes 0–8. Its T2P open-drain output encodes PSE-allocated power via duty-cycle modulation (25%, 50%, or Hi-Z) based on event count and AUX status.
It drives an external N-channel MOSFET via HSGATE with charge-pump-assisted gate control (VGOC = 10–18 V), enabling low RDS(ON) solutions; hot-swap thresholds are VHSON = 35–37 V and VHSOFF = 30–31 V with 3 V hysteresis. Overtemperature protection disables classification above 150°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VPORT Operating Range | 60 V max - supports full IEEE 802.3bt Type 4 PSE voltage swing without clamping or derating. |
| Detection Signature | 24.4 kΩ ±0.7 kΩ - precise, temperature-compensated resistance enabling reliable PSE detection per IEEE 802.3 Clause 33. |
| Classification Events | Up to 5 events - enables full Class 8 (71.3 W) negotiation and demotion handling per IEEE 802.3bt Clause 33.3.3. |
| T2P Encoding | 25% / 50% / Hi-Z duty cycle - unambiguously signals allocated power level (e.g., 25% = 71.3 W) to host MCU without protocol overhead. |
| AUX Threshold | 6.3 V ±0.2 V - triggers auxiliary mode at VAUX ≥ 6.3 V, allowing seamless 9–60 V auxiliary supply takeover with signature disconnect. |
| Hot-Swap Turn-On | 35–37 V - ensures MOSFET activation only after PSE completes classification, preventing premature inrush. |
| Junction Temp Range | –40°C to 125°C - qualified for outdoor security camera and industrial display environments with no derating. |
Pinout & Package
LT4294IDD#PBF uses a 10-lead 3mm × 3mm plastic DFN package with exposed pad (Pin 11) electrically and thermally connected to GND. The package is rated for –40°C to 85°C operating junction temperature and features θJC = 5°C/W for efficient heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1, 5, Exposed Pad 11) | Ground reference and thermal sink | Must be soldered to PCB ground plane; exposed pad is mandatory for thermal performance and electrical stability. |
| AUX (Pin 2) | Auxiliary supply sense input | Triggers auxiliary mode when ≥6.3 V; provides hysteresis via IAUXH = 3.2–7 µA sink current below threshold. |
| RCLASS (Pin 3) | Primary classification resistor terminal | Connects to 1% resistor to GND to set nominal class current (e.g., 34.8 Ω for Class 4 = 40 mA). |
| RCLASS++ (Pin 4) | Secondary classification resistor terminal | Enables 5-event classification; determines Class 5–8 via dual-resistor configuration per Table 2. |
| T2P (Pin 6) | PSE-allocated power indicator | Open-drain output encoding power level as duty cycle (25% = 71.3 W, 50% = 51 W, Hi-Z = ≤13 W). |
| PWRGD (Pin 7) | Power-good status flag | Open-drain output held low until HSGATE reaches ~7 V above HSSRC, enabling safe downstream power-up. |
| HSSRC (Pin 8) | External MOSFET source connection | Direct tie to MOSFET source; sets reference for HSGATE drive and current sensing path. |
| HSGATE (Pin 9) | Hot-swap MOSFET gate driver | Charge-pump-driven output (VGOC = 10–18 V) controlling external N-MOSFET turn-on/turn-off timing. |
| VPORT (Pin 10) | PoE input rail and MOSFET drain node | Accepts 0–60 V PoE input; carries full port current; connects to MOSFET drain and input capacitor (0.1 µF). |
Key Features
| Feature | Design Value |
|---|---|
| IEEE 802.3bt single-signature compliance | Full support for Classes 0–8 with 5-event classification and T2P-based power reporting-no second PD controller required. |
| Integrated signature resistor | 24.4 kΩ ±0.7 kΩ trimmed resistor eliminates external component, reduces BOM count, and maintains detection accuracy across –40°C to 125°C. |
| External N-channel MOSFET control | Charge-pump gate drive (VGOC = 10–18 V) enables use of low-cost, low-RDS(ON) N-MOSFETs-reducing conduction loss vs. P-MOSFET solutions. |
| Auxiliary supply override | Seamless transition to 9–60 V auxiliary input with automatic signature disconnect, classification disable, and T2P max-power indication. |
| Overtemperature protection | Active shutdown of HSGATE and classification logic above 150°C junction temperature-prevents thermal runaway during abnormal conditions. |
Applications
| Outdoor Security Cameras | Commercial Information Displays |
|---|---|
|
Use Scenario: IP-based security cameras deployed outdoors require robust 71.3W PoE+ power with surge resilience and auxiliary fallback for battery backup or AC adapter redundancy. IC Role / Device Role / Timing Role: LT4294IDD#PBF acts as the primary PD interface controller, managing IEEE 802.3bt detection, 5-event classification, T2P-encoded power reporting, and hot-swap MOSFET control. Use Value: Enables full 71.3W operation for pan-tilt-zoom (PTZ) and heater-equipped cameras while maintaining backward compatibility with legacy 802.3at switches and surviving 100V surge transients. |
Use Scenario: Large-format digital signage in retail and transit hubs demands high-reliability PoE power with thermal margin and auxiliary supply capability for uninterrupted operation during network outages. IC Role / Device Role / Timing Role: LT4294IDD#PBF serves as the IEEE 802.3bt PD controller, coordinating classification, power-good signaling, and auxiliary mode handover to maintain display uptime. Use Value: Delivers 71.3W at full ambient range (–40°C to 85°C), supports auxiliary input as low as 9V, and eliminates need for heatsinks via N-MOSFET efficiency-reducing system size and cost. |
| High-Temperature Industrial PDs | Wireless Data Access Points |
|
Use Scenario: Industrial wireless gateways mounted near motors or HVAC systems operate in sustained 85°C ambient with strict thermal design constraints and PoE power continuity requirements. IC Role / Device Role / Timing Role: LT4294IDD#PBF provides IEEE 802.3bt PD interface with overtemperature protection, wide junction range (–40°C to 125°C), and auxiliary supply fallback for mission-critical uptime. Use Value: Maintains functional safety up to 125°C junction temperature, prevents thermal shutdown under continuous load, and allows graceful transition to auxiliary power during PoE interruption. |
Use Scenario: High-density Wi-Fi 6/6E access points require >60W PoE power for multi-radio operation, beamforming, and real-time analytics-while coexisting with legacy infrastructure. IC Role / Device Role / Timing Role: LT4294IDD#PBF executes IEEE 802.3bt mutual identification, negotiates Class 8 (71.3W), reports allocation via T2P, and controls hot-swap MOSFET for clean inrush. Use Value: Achieves full 71.3W delivery with <1.5W internal dissipation during classification, supports 5-event negotiation for accurate power allocation, and ensures interoperability with all IEEE 802.3bt PSE types. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar powered device interface controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT4295IMS#PBF | Integrates 60V synchronous buck regulator; no external MOSFET needed; smaller solution size but fixed 5V/3.3V output. | Best for space-constrained, lower-power PDs (<30W) where integrated regulation suffices; not suitable for 71.3W or variable-output designs. | Select LT4295IMS#PBF only if system requires integrated DC/DC conversion and total output power ≤30W; otherwise, LT4294IDD#PBF offers higher flexibility and efficiency at full 71.3W. |
| LT4275AIMS#PBF | IEEE 802.3at-only (25.5W max); pin-compatible but lacks 5-event classification, T2P encoding, and 71.3W support. | Valid for legacy 802.3at deployments only; cannot negotiate Class 5–8 or report power via T2P; no auxiliary override below 12V. | Choose LT4275AIMS#PBF only for cost-sensitive 25.5W applications with no future 802.3bt upgrade path; LT4294IDD#PBF provides forward compatibility and full 71.3W capability. |
Compared with LT4295IMS#PBF, LT4294IDD#PBF enables higher power (71.3W vs. ≤30W), external MOSFET optimization, and flexible output voltage design; compared with LT4275AIMS#PBF, it adds 5-event classification, T2P power reporting, auxiliary override down to 9V, and full IEEE 802.3bt compliance-making it the only choice for new 71.3W PD designs.
Availability
LT4294IDD#PBF is available at Aetrix Electronics and suitable for outdoor security camera equipment, commercial information displays, and high-temperature industrial PDs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT4294IDD#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, communications, automotive, and aerospace markets with precision power, interface, and signal chain solutions.
The LT4294 belongs to Analog Devices' Power over Ethernet (PoE) PD controller product line, engineered specifically for IEEE 802.3bt-compliant high-power powered devices requiring robust classification, thermal resilience, and auxiliary supply interoperability.
FAQ
What is the maximum power level supported by the LT4294IDD#PBF?
The LT4294IDD#PBF supports up to 71.3W of input power as defined by IEEE 802.3bt Class 8. This is achieved through 5-event classification and confirmed by its specification "Supports Up to 71.3W PDs" in the official datasheet. The LT4294IDD#PBF does not limit output power-it enables the full Class 8 allocation when configured with appropriate RCLASS and RCLASS++ resistors and paired with a suitably rated external MOSFET and downstream converter.
Does the LT4294IDD#PBF include an integrated MOSFET?
No, the LT4294IDD#PBF does not include an integrated MOSFET. It is a controller IC that drives an external low RDS(ON) N-channel MOSFET via the HSGATE pin. This architecture maximizes efficiency and thermal performance, avoids fixed MOSFET limitations, and allows designers to select optimal FETs for their specific voltage, current, and thermal requirements-unlike integrated solutions such as the LT4295.
How does the T2P pin indicate allocated power on the LT4294IDD#PBF?
The T2P pin on the LT4294IDD#PBF is an open-drain output that encodes PSE-allocated power using duty-cycle modulation: 25% low-time indicates 71.3W (Class 8), 50% indicates 51W (Class 6), and Hi-Z (high-impedance) indicates ≤13W (Classes 0–3). This encoding is determined by the number of classification events and AUX pin state, and is explicitly defined in Table 3 of the LT4294IDD#PBF datasheet.
Can the LT4294IDD#PBF operate with auxiliary supply voltages below 12V?
Yes, the LT4294IDD#PBF supports auxiliary supply override as low as 9V, with a precise AUX threshold of 6.3V ±0.2V. When VAUX exceeds this threshold, the device enters auxiliary mode: signature disconnects, classification halts, HSGATE pulls low, and T2P indicates maximum available power. This capability is confirmed in the "Configurable Aux Power Support as Low as 9V" feature list and Electrical Characteristics table.
Is the LT4294IDD#PBF pin-compatible with earlier Analog Devices PD controllers?
Yes, the LT4294IDD#PBF is pin-compatible with the LT4275 family (e.g., LT4275A/B/C) as explicitly stated in the datasheet: "Pin-for-pin compatibility with the LT4275 family of PD Interface Controllers enables easy migration between LTPoE++ PDs and IEEE 802.3bt-compliant PDs." This allows drop-in replacement in existing layouts while upgrading to full 802.3bt functionality-including 5-event classification and T2P signaling.
LT4294IDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Controller (PD)
- Number of Channels:
- 1
- Power - Max:
- 71 W
- Internal Switch(s):
- No
- Auxiliary Sense:
- Yes
- Standards:
- 802.3at (PoE+), 802.3af (PoE), 802.3bt
- Voltage - Supply:
- 60V (Max)
- Current - Supply:
- 2mA
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT4294IDD#PBF FAQ
1.How can I place an order for LT4294IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT4294IDD#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT4294IDD#PBF reliable?
The price and inventory of LT4294IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT4294IDD#PBF is usually 5 days.
3.What payment methods are accepted for LT4294IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT4294IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT4294IDD#PBF?
LT4294IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT4294IDD#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT4294IDD#PBF?
For technical support, including LT4294IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT4294IDD#PBF requirements.
6.How does Aetrix verify that LT4294IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT4294IDD#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT4294IDD#PBF meets industry standards.
7.What is the process for return or replacement of LT4294IDD#PBF?
All LT4294IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT4294IDD#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT4294IDD#PBF part is unused and in its original packaging.
Return procedure for LT4294IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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