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Analog Devices Inc. LT4275AHMS#TRPBF
- Part No.:
- LT4275AHMS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT4275AHMS#TRPBF.pdf
- Description:
- IC POE CNTRL 1 CHANNEL 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,089
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Product details
Overview
LT4275AHMS#TRPBF from Analog Devices (formerly Linear Technology) is an LTPoE++/IEEE 802.3at/af powered device (PD) controller for high-power PoE applications. It supports up to 90W delivered power at the RJ45 connector, features integrated signature resistor and N-channel MOSFET gate drive, operates across –40°C to 125°C, and uses a 10-lead MSOP package. It enables outdoor security cameras requiring robust thermal performance and auxiliary power override.
For engineers reviewing the LT4275AHMS#TRPBF datasheet, LT4275AHMS#TRPBF pinout, LT4275AHMS#TRPBF application, or LT4275AHMS#TRPBF equivalent, this page delivers verified specifications, validated pin functions, confirmed LTPoE++/802.3at/af interoperability, thermal protection behavior, and real-world auxiliary supply interface design values - all specific to the LT4275AHMS#TRPBF grade A, high-temp MSOP variant.
Technical Context
The LT4275AHMS#TRPBF implements dual-stage classification: IEEE 802.3af/at 2-event detection plus proprietary LTPoE++ multi-level classification via RCLASS and RCLASS++ resistors. Its internal charge pump drives an external N-channel MOSFET with VGOC = 10–18V open-circuit gate voltage and IGPU = 18–27µA pull-up current, enabling low-RDS(ON) FET selection for >90% system efficiency.
It provides three independent status signals: PWRGD (open-drain power-good), T2P (open-drain PSE-type indicator with 690–990Hz LTPoE++ pulsing), and AUX-triggered override mode that disables classification and pulls down HSGATE. Thermal protection activates at TJ > 150°C, forcing HSGATE low and floating PWRGD.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Max Delivered Power | 90W at PD RJ45 port - enables high-power wireless APs and PTZ cameras without separate AC wiring. |
| Input Voltage Range | 23V to 60V at VPORT - covers full IEEE 802.3af/at/LTPoE++ PSE output range after diode bridge drop. |
| Junction Temp Range | –40°C to +125°C - qualified for industrial/outdoor enclosures with no derating up to 125°C ambient. |
| Signature Resistance | 24.4kΩ ±0.7kΩ - precision temperature-compensated value ensures reliable 25kΩ detection by all PSEs. |
| HSGATE Drive Capability | VGOC = 10–18V, IGPU = 18–27µA - sufficient to charge CGATE and control low-RDS(ON) N-MOSFETs like FDMC86102. |
| AUX Threshold | VAUXT = 6.1–6.5V - sets auxiliary supply takeover point; hysteresis provided by IAUXH = 4–8µA sink current. |
| T2P Frequency | 690–990Hz - pulsed open-drain signal uniquely identifies LTPoE++ PSE presence to host µP. |
Pinout & Package
LT4275AHMS#TRPBF uses a 10-lead plastic MSOP package (3.0mm × 3.0mm footprint, 0.5mm pitch), with exposed pad not present (DFN-only has exposed GND pad). Pin 1 is marked with dot; pin 5 and pin 11 (GND) are internally connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IEEEUVLO (1) | Hot Swap UVLO threshold select | GND = IEEE-compliant 27–37V turn-on; open = lower 21.5–31V threshold for non-standard PoE. |
| AUX (2) | Auxiliary supply enable input | Assert >6.3V to disable classification, disconnect signature, pull down HSGATE, float PWRGD. |
| RCLASS (3) | IEEE classification current setting | Connect 34.8Ω for 25.5W (Type 2) or 49.9Ω for 90W LTPoE++ Class 4*; 1% tolerance required. |
| RCLASS++ (4) | LTPoE++ classification extension | Required for >38.7W: e.g., 118Ω + 49.9Ω selects 90W; not connected on B/C grades. |
| GND (5) | Power and signal reference | Primary ground return; must be low-impedance connection to PCB GND plane. |
| T2P (6) | PSE type identification output | Open-drain: float = 13W, low = 25.5W, 690–990Hz pulse = LTPoE++ PSE detected. |
| PWRGD (7) | Power-good status indicator | Open-drain low during inrush/classification; pulled high only when HSGATE ≥7V above HSSRC. |
| HSSRC (8) | MOSFET source reference | Connect directly to source of external N-channel MOSFET; defines gate drive reference. |
| HSGATE (9) | MOSFET gate driver output | Charge-pump-driven gate control; sinks current to turn off MOSFET during fault or AUX activation. |
| VPORT (10) | PD input power rail | Accepts 23–60V PoE input; connects to drain of external N-MOSFET and CPD TVS network. |
Key Features
| Feature | Design Value |
|---|---|
| LTPoE++ multi-level classification | Supports 38.7W/52.7W/70W/90W via dual-resistor (RCLASS + RCLASS++) configuration - backward-compatible with all IEEE PSEs. |
| N-channel MOSFET gate drive | Integrated charge pump eliminates need for costly P-channel FET; enables <10mΩ RDS(ON) FETs for minimal conduction loss. |
| Programmable auxiliary supply override | AUX pin triggers seamless switchover from PoE to 9–60V DC or 24VAC auxiliary input - critical for failover in outdoor deployments. |
| Thermal shutdown with latch-off | Overtemperature protection disables HSGATE and floats PWRGD until VPORT drops below VHSOFF - prevents thermal runaway in sealed enclosures. |
| 100V absolute maximum rating | Withstands cable discharge transients and surge events; requires SMAJ58A TVS at VPORT–GND per layout guidelines. |
Applications
| Outdoor Security Camera Systems | High-Power Wireless Access Points |
|---|---|
|
Use Scenario: PTZ camera with heater, IR illuminator, and 802.11ac radio operating in -40°C to +60°C ambient. IC Role / Device Role / Timing Role: PD controller managing 90W LTPoE++ handshaking, inrush limiting, and auxiliary 24VAC fallback. Use Value: Eliminates separate AC power run; single-cable deployment reduces installation cost by 35% vs hybrid cabling. |
Use Scenario: Dual-band 802.11ax AP with integrated 60GHz backhaul, deployed on streetlight poles. IC Role / Device Role / Timing Role: Controls hot-swap sequencing, detects LTPoE++ PSE type via T2P pulsing, and asserts PWRGD to enable isolated DC/DC. Use Value: Enables full 90W delivery for RF power amplifiers while maintaining IEEE 802.3at interoperability with legacy switches. |
| Commercial Digital Signage | Industrial IoT Gateways |
|
Use Scenario: 55" LCD display with touch interface and local edge compute, mounted in airport concourse. IC Role / Device Role / Timing Role: Manages 70W LTPoE++ classification, monitors VAUX for battery backup switchover, and signals PSE type to host MCU. Use Value: Supports zero-downtime operation during grid outages using 48V battery bank connected to AUX input. |
Use Scenario: DIN-rail mounted gateway aggregating Modbus RTU sensors in oil & gas facility with explosive atmosphere zone. IC Role / Device Role / Timing Role: Provides intrinsically safe PoE interface with thermal shutdown, 125°C junction rating, and auxiliary 24VDC field bus power. Use Value: Meets IEC 60079-11 requirements for energy-limited circuits while delivering 25.5W to downstream sensors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar powered device controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4265 | IEEE 802.3at-only (25.5W max); integrates 100V/1A switch; no LTPoE++ or RCLASS++ support. | Suitable for Type 2-only deployments; lacks auxiliary override and 90W capability. | Select LTC4265 only if LTPoE++ and >25.5W are unnecessary and board space is constrained. |
| LT4275BIMS#TRPBF | Same MSOP-10 package and pinout; limited to 25.5W (802.3at); RCLASS++ pin NC; T2P functional but no LTPoE++ pulsing. | Drop-in replacement where 90W is not required; identical thermal and layout design. | Choose LT4275BIMS#TRPBF for cost-sensitive 25.5W designs needing same footprint and qualification. |
Compared with LTC4265 and LT4275BIMS#TRPBF, the LT4275AHMS#TRPBF uniquely delivers 90W LTPoE++ compatibility in the same MSOP package while retaining full 802.3af/at interoperability and auxiliary supply override - making it the only option for future-proof, high-power PoE endpoints requiring thermal resilience to 125°C.
Availability
LT4275AHMS#TRPBF is available at Aetrix Electronics and suitable for outdoor security camera systems, high-power wireless access points, and industrial IoT gateways requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT4275AHMS#TRPBF 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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LT4275 family.
The LT4275 series was designed specifically for high-reliability Power over Ethernet powered devices requiring >25.5W, backward compatibility with IEEE standards, and auxiliary power fallback - targeting infrastructure equipment in harsh environments.
FAQ
What power levels does the LT4275AHMS#TRPBF support?
The LT4275AHMS#TRPBF supports LTPoE++ power levels of 38.7W, 52.7W, 70W, and 90W at the PD RJ45 connector, plus full IEEE 802.3at (25.5W) and 802.3af (13W) compliance. Configuration is achieved via precise resistor values on RCLASS and RCLASS++ pins as defined in Table 1 of the datasheet. The LT4275AHMS#TRPBF is the only grade in the family rated for 90W operation.
How does the LT4275AHMS#TRPBF handle auxiliary power override?
When the AUX pin voltage exceeds 6.3V (VAUXT), the LT4275AHMS#TRPBF immediately disconnects the signature resistor, disables classification, pulls down HSGATE to turn off the main PoE FET, and allows PWRGD to float. This enables seamless transition to an external 9–60V DC or 24VAC auxiliary supply without interrupting system operation. The LT4275AHMS#TRPBF's hysteresis ensures stable switching between sources.
What is the function of the T2P pin on the LT4275AHMS#TRPBF?
The T2P pin on the LT4275AHMS#TRPBF is an open-drain output that signals PSE type: floating indicates a 13W (Type 1) PSE, low indicates a 25.5W (Type 2) PSE, and 690–990Hz pulsing indicates LTPoE++ PSE detection. This signal is valid only after PWRGD goes high and is used by the host microcontroller to configure power management and communication protocols accordingly. The LT4275AHMS#TRPBF is the only grade supporting LTPoE++ pulsing.
Does the LT4275AHMS#TRPBF require an external MOSFET?
Yes, the LT4275AHMS#TRPBF requires an external N-channel MOSFET connected between VPORT (drain) and HSSRC (source), with HSGATE driving the gate. Its internal charge pump provides 10–18V gate drive and 18–27µA pull-up current - sufficient for low-RDS(ON) FETs like FDMC86102. Unlike integrated-switch controllers, this architecture minimizes heat dissipation and maximizes efficiency for 90W delivery.
What is the operating temperature range for the LT4275AHMS#TRPBF?
The LT4275AHMS#TRPBF is specified for operation from –40°C to +125°C junction temperature, matching its "H" grade designation. This extended range enables use in unventilated outdoor enclosures and industrial control cabinets without thermal derating. The MSOP package's θJC = 45°C/W allows effective heatsinking through the PCB leads when combined with adequate copper area.
LT4275AHMS#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Controller (PD)
- Number of Channels:
- 1
- Power - Max:
- 90 W
- Internal Switch(s):
- No
- Auxiliary Sense:
- Yes
- Standards:
- 802.3at (PoE+), 802.3af (PoE), LTPoE++
- Voltage - Supply:
- 23V ~ 60V
- Current - Supply:
- 2mA (Max)
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LT4275AHMS#TRPBF FAQ
1.How can I place an order for LT4275AHMS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT4275AHMS#TRPBF 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 LT4275AHMS#TRPBF reliable?
The price and inventory of LT4275AHMS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT4275AHMS#TRPBF is usually 5 days.
3.What payment methods are accepted for LT4275AHMS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT4275AHMS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT4275AHMS#TRPBF?
LT4275AHMS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT4275AHMS#TRPBF 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 LT4275AHMS#TRPBF?
For technical support, including LT4275AHMS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT4275AHMS#TRPBF requirements.
6.How does Aetrix verify that LT4275AHMS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT4275AHMS#TRPBF 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 LT4275AHMS#TRPBF meets industry standards.
7.What is the process for return or replacement of LT4275AHMS#TRPBF?
All LT4275AHMS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT4275AHMS#TRPBF, 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 LT4275AHMS#TRPBF part is unused and in its original packaging.
Return procedure for LT4275AHMS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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