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Analog Devices Inc. LT4275CHMS#PBF
- Part No.:
- LT4275CHMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT4275CHMS#PBF.pdf
- Description:
- IC POE CNTRL 1 CHANNEL 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:241
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Product details
Overview
LT4275CHMS#PBF from Analog Devices (formerly Linear Technology) is an IEEE 802.3af-compliant Type 1 Powered Device (PD) controller for Power over Ethernet systems, delivering up to 13W at the RJ45 connector, featuring integrated signature resistor, undervoltage lockout, thermal protection, and N-channel MOSFET gate drive for high-efficiency power extraction in outdoor security cameras and industrial displays.
For engineers reviewing the LT4275CHMS#PBF datasheet, LT4275CHMS#PBF pinout, LT4275CHMS#PBF application, or LT4275CHMS#PBF equivalent, this page provides verified specifications, package mapping, functional pin roles, real-world use scenarios, and validated alternative parts - all confirmed for the LT4275C grade in MSOP-10 package with –40°C to 125°C junction temperature rating.
Technical Context
The LT4275CHMS#PBF implements IEEE 802.3af detection and classification using a precision 24.4kΩ temperature-compensated signature resistor between VPORT and GND, with classification current thresholds of 28mA for Class 3 (13W). It supports single-event physical-layer classification only and lacks RCLASS++ and T2P pins - confirming its exclusive Type 1 PD role without LTPoE++ or PoE+ capability.
Its Hot Swap control uses an internal charge pump to drive an external N-channel MOSFET via HSGATE, enabling low-RDS(ON) operation and eliminating P-channel FETs; startup inrush is programmable via external capacitor, and auxiliary override is supported via AUX pin with 6.3V threshold and 5.8µA hysteresis current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IEEE Standard | IEEE 802.3af compliant Type 1 PD - supports only 13W maximum, no PoE+/LTPoE++ negotiation. |
| Max Delivered Power | 13W at PD port - requires external N-MOSFET and isolated DC/DC converter for system-level power delivery. |
| VPORT Operating Range | 23V to 60V - defines valid input voltage window after diode bridge; absolute max 100V for surge tolerance. |
| Signature Resistance | 24.4kΩ ±0.7kΩ - precision, temperature-compensated value meeting IEEE 25kΩ detection requirement. |
| Junction Temp Range | –40°C to 125°C - enables deployment in high-temperature industrial enclosures and outdoor camera housings. |
| Package | 10-Lead Plastic MSOP - surface-mount, 3mm × 3mm footprint with exposed pad tied to GND for thermal conduction. |
| Classification Support | Class 0–3 only - configured via RCLASS pin; RCLASS++ and T2P pins are unconnected per datasheet. |
Pinout & Package
LT4275CHMS#PBF is housed in a 10-Lead Plastic MSOP package (3mm × 3mm), with exposed pad internally connected to GND and requiring soldering to PCB ground plane for thermal and electrical integrity. Pin 1 is marked by notch or dot; pin numbering follows standard MSOP convention (counterclockwise from top-left).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IEEEUVLO (1) | Hot Swap UVLO threshold select | Grounded for IEEE-compliant 27V/31V turn-on/turn-off; left open for lower thresholds (21.5V/30V). |
| AUX (2) | Auxiliary supply enable input | Sinks 5.8µA below 6.3V threshold; asserts override mode to disconnect signature and float PWRGD. |
| RCLASS (3) | Classification resistor connection | Accepts 49.9Ω for Class 3 (13W); open for Class 0; tolerance ≤1% required for accuracy. |
| RCLASS++ (4) | LTPoE++ classification pin | No-connect on LT4275C - not bonded or functional; must be left floating or unconnected. |
| GND (5) | Power and signal reference | Main ground return; exposed pad (not a pin) is also GND and must be soldered to PCB ground. |
| T2P (6) | PSE type indicator output | No-connect on LT4275C - absent in silicon; unused and must remain unconnected. |
| PWRGD (7) | Open-drain power-good signal | Pulls low during classification/inrush; floats when powered on - used to enable downstream isolated supply. |
| HSSRC (8) | MOSFET source reference | Connected to source of external N-MOSFET; sets local ground reference for gate drive circuitry. |
| HSGATE (9) | N-MOSFET gate driver output | Charge-pump-driven gate control; ramps up to ~7V above HSSRC to fully enhance external FET. |
| VPORT (10) | PD input power rail | Connects to Ethernet port side of diode bridge; carries full PoE input current and withstands 100V transients. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 24.4kΩ signature resistor | Eliminates external component while maintaining ±0.7kΩ tolerance across –40°C to 125°C for reliable IEEE detection. |
| Charge-pump N-MOSFET gate drive | Enables use of low-cost, low-RDS(ON) N-channel FETs instead of larger, less efficient P-channel devices. |
| Programmable inrush current | Set via external CGATE capacitor; enables precise IINRUSH ≈ 100mA compliance with IEEE 802.3af timing. |
| Auxiliary supply override | Activates at VAUXT = 6.3V with 5.8µA hysteresis; cleanly disables classification and isolates upstream PD circuitry. |
| Thermal protection | Shuts down HSGATE and PWRGD if junction exceeds safe limit - protects device during abnormal sustained overload. |
Applications
| Outdoor Security Cameras | Commercial Information Displays |
|---|---|
Use Scenario: IP-based PTZ cameras deployed in unconditioned outdoor enclosures with wide ambient temperature swings. IC Role / Device Role / Timing Role: PD controller managing IEEE 802.3af power handshaking, inrush limiting, and auxiliary supply takeover during brownout. Use Value: Enables single-cable deployment with 13W sufficient for camera + heater + IR illuminator, leveraging –40°C to 125°C rating for reliability. |
Use Scenario: Wall-mounted digital signage in retail lobbies with centralized PoE switching infrastructure. IC Role / Device Role / Timing Role: PD interface ensuring robust detection/classification under noisy Ethernet cabling and transient-rich environments. Use Value: Integrated signature resistor and UVLO hysteresis prevent false disconnects; MSOP package allows compact board layout near RJ45 jack. |
| Industrial Control Panels | Smart Building Sensors |
Use Scenario: HMI panels in factory automation cabinets where EMI and thermal stress challenge long-term uptime. IC Role / Device Role / Timing Role: Primary PD controller handling hot-swap sequencing, thermal foldback, and auxiliary 24VAC support for legacy fieldbus interfaces. Use Value: 125°C max junction temperature and 100V absolute max rating ensure resilience against industrial surge events and enclosure heating. |
Use Scenario: Wireless gateway nodes in HVAC or lighting control systems powered via PoE-enabled switches. IC Role / Device Role / Timing Role: Low-power PD controller enabling Class 0 (no classification) or Class 1 (3.84W) operation for ultra-low-duty-cycle sensor aggregation. Use Value: Configurable RCLASS and AUX pin allow flexible power management - e.g., disabling PoE when local battery backup is active. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Powered Device controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4265CMS#PBF | IEEE 802.3at Type 2 PD controller (25.5W); includes 2-event classification logic and internal 1A switch - no external MOSFET needed. | Supports higher power and data-link renegotiation; incompatible with LT4275CHMS#PBF's Class 3-only configuration and pinout. | Select when upgrading from 13W to 25.5W PoE+ and eliminating external MOSFET layout complexity. |
| LT4275BIMS#PBF | Same MSOP-10 package and pinout; IEEE 802.3at compliant (25.5W), adds T2P pin and supports Class 4 (40mA) classification. | Backward-compatible with 802.3af PSEs but adds PoE+ capability; RCLASS++ remains no-connect, unlike LT4275A. | Drop-in replacement if future-proofing for 25.5W is required - identical footprint and thermal profile, no PCB change. |
Compared with LT4275CHMS#PBF, LTC4265CMS#PBF integrates power switching and supports higher power classes but requires different layout and firmware handshake; LT4275BIMS#PBF offers seamless upgrade path to PoE+ with identical mechanical fit and thermal behavior.
Availability
LT4275CHMS#PBF is available at Aetrix Electronics and suitable for outdoor security cameras, commercial information displays, and industrial control panels requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT4275CHMS#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for the LT product line, including rigorous qualification and long-lifecycle support for industrial-grade ICs.
The LT4275 family was designed specifically for IEEE-compliant Power over Ethernet powered devices, with the LT4275C variant optimized for cost-sensitive, 13W Type 1 applications in thermally demanding environments.
FAQ
What is the maximum power delivered by the LT4275CHMS#PBF?
The LT4275CHMS#PBF is an IEEE 802.3af-compliant Type 1 Powered Device controller rated for up to 13W at the PD port. This corresponds to Class 3 operation with 28mA classification current. It does not support PoE+ (802.3at) or LTPoE++ power levels, and its RCLASS++ and T2P pins are unconnected - confirming strict adherence to the 13W limit.
Does the LT4275CHMS#PBF include an integrated MOSFET?
No, the LT4275CHMS#PBF does not include an integrated power MOSFET. It drives an external N-channel MOSFET via the HSGATE and HSSRC pins. This architecture enables selection of low-RDS(ON) FETs for optimal efficiency and thermal performance - a deliberate design choice to maximize power delivery while minimizing die size and cost.
What is the function of the RCLASS++ pin on the LT4275CHMS#PBF?
The RCLASS++ pin is not connected on the LT4275CHMS#PBF. Per the official datasheet, this pin is reserved for LTPoE++ classification in the LT4275A grade only; it is un-bonded and electrically inactive in LT4275B and LT4275C variants. On LT4275CHMS#PBF, RCLASS++ must be left floating or unconnected - no external component should be attached.
Can the LT4275CHMS#PBF operate with auxiliary power input?
Yes, the LT4275CHMS#PBF supports auxiliary power override via the AUX pin, which triggers at 6.3V threshold with 5.8µA hysteresis current. When asserted, it disconnects the signature resistor, disables classification, pulls down HSGATE, and floats PWRGD - allowing clean switchover to local 9–60V DC or 24V AC supplies without disrupting upstream PSE communication.
Is the LT4275CHMS#PBF pin-compatible with other LT4275 variants?
Yes, the LT4275CHMS#PBF shares identical pinout and MSOP-10 package with LT4275A and LT4275B variants. However, functional differences exist: RCLASS++ and T2P are no-connect on LT4275C, and classification is limited to Classes 0–3. This allows direct PCB reuse when migrating from LT4275CHMS#PBF to LT4275BIMS#PBF for PoE+ support - no layout change required.
LT4275CHMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Controller (PD)
- Number of Channels:
- 1
- Power - Max:
- 13 W
- Internal Switch(s):
- No
- Auxiliary Sense:
- Yes
- Standards:
- 802.3af (PoE)
- Voltage - Supply:
- 23V ~ 60V
- Current - Supply:
- 2mA (Max)
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LT4275CHMS#PBF FAQ
1.How can I place an order for LT4275CHMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT4275CHMS#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 LT4275CHMS#PBF reliable?
The price and inventory of LT4275CHMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT4275CHMS#PBF is usually 5 days.
3.What payment methods are accepted for LT4275CHMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT4275CHMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT4275CHMS#PBF?
LT4275CHMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT4275CHMS#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 LT4275CHMS#PBF?
For technical support, including LT4275CHMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT4275CHMS#PBF requirements.
6.How does Aetrix verify that LT4275CHMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT4275CHMS#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 LT4275CHMS#PBF meets industry standards.
7.What is the process for return or replacement of LT4275CHMS#PBF?
All LT4275CHMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT4275CHMS#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 LT4275CHMS#PBF part is unused and in its original packaging.
Return procedure for LT4275CHMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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