Features and Benefits
- 12 Independent PSE Channels
- Compliant with IEEE 802.3at Type 1 and 2
- Chipset Provides Electrical Isolation
- Reduced BOM Cost
- Eliminates up to 6 High Speed Opto-Couplers
- Eliminates Isolated 3.3V Power Supply
- Low Power Dissipation
- 0.25Ω Sense Resistance Per Channel
- Very High Reliability 4-Point PD Detection
- 2-Point Forced Voltage
- 2-Point Forced Current
- VEE and VPORT Monitoring
- 1 Second Rolling IPORT Averaging
- Supports 2-Pair and 4-Pair Output Power
- 1MHz I2C Compatible Serial Control Interface
- Available In Three Power Grades
- A-Grade – LTPoE++™ 38.7W to 90W
- B-Grade – PoE+ 25.5W
- C-Grade – PoE 13W
- Available In 52-Lead 7mm × 8mm (LTC4270) and 24‑Lead 4mm × 4mm (LTC4271) QFN Packages
The LTC4270/LTC4271 chipset is a 12-port power sourcing equipment (PSE) controller designed for use in IEEE 802.3at Type 1 and Type 2 (high power) compliant Power over Ethernet (PoE) systems. Transformer-isolated communication protocol replaces expensive opto-couplers and complex isolated 3.3V supply resulting in significant BOM cost savings. The LTC4270/LTC4271 chipset delivers lowest-in-industry heat dissipation by utilizing low-RDS(ON) external MOSFETs and 0.25Ω sense resistors.
Advanced power management features include per-port 12‑bit current monitoring ADCs, DAC-programmable current limit, and versatile fast shut-down of preselected ports. Advanced power management host software is available under a no-cost license. PD discovery uses a proprietary dual-mode 4-point detection mechanism ensuring excellent immunity from false PD detection. Midspan PSEs are supported with 2-event classification and a 2 second backoff timer. The LTC4270/LTC4271 includes an I2C serial interface operable up to 1MHz.
The LTC4270/LTC4271 is available in multiple power grades allowing delivered PD power up to 90W.
- PoE PSE Switches/Routers
- PoE PSE Midspans
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (3)
Demonstration kit DC1840C is a 12-port Ethernet Alliance™ certified IEEE 802.3at Type 2 power sourcing equipment (PSE) composed of a DC1682B daughter card and DC1680B mother board. The kit is used for evaluation of the LTC4270B and LTC4271 PSE chipset. Up to 12 powered devices (PDs) can be connected and powered from this system using a single power supply. A DC590 is connected to the DC1840 for I2C interfacing with QuikEval™. This demonstration manual provides a Quick Start Procedure, a DC1682 overview, a DC1680 overview, schematics, and layout printouts.
Demonstration kit DC1843B is an 8-port Ethernet Alliance™ certified IEEE 802.3at Type 2 power sourcing equipment (PSE) composed of a DC1842B daughter card and DC1680B motherboard. The kit is used for evaluation of the LTC4290B and LTC4271 PSE chipset. Up to 8 powered devices (PDs) can be connected and powered from this system using a single power supply. A DC590 is connected to the DC1843 for I2C interfacing with QuikEval™. This demonstration manual provides a Quick Start Procedure, a DC1842B overview, a DC1680B overview, schematics, and layout printouts. Refer to the Layout Guide for Demonstration Circuit 1842B when laying out the LTC4290B/LTC4271 circuit. Contact Analog Devices for this document.
The DC1842B has increased surge protection over the DC1842A. The DC1680B uses discrete Ethernet transformers while the DC1680A has an integrated 12-port RJ45 jack.
Product Selection Guide (1)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.