A PoE controller that can simultaneously realize 10 Gbps and 71.3W power supply with 1 cable

The LTC4291 / LTC4292 chipset is a PoE controller from Analog Devices. PoE is Power supply over Ethernet.

Applications that previously required 2 power and LAN cables such as:

• Surveillance cameras
• IP phone
• Measuring equipment
• Network equipment

can combine communication and power into 1 LAN cables.

The LTC4292 / LTC4291 chipset also supports 4 ports that are compliant with 802.3af, 802.3at and 802.3bt. This allows simultaneous power to multiple LAN cables.

Configuration Example

This article introduces the below features of LTC4292/LTC4291.

1. 1 LAN cables provide up to 71.3W of power
2. Backward compatible with traditional PoE
3. The calorific value of concern is the lowest in the industry.
4. Temperature range is -40 to 85℃, suitable for industrial use
5. Minimal peripheral components, so low cost

1 LAN cables provide up to 71.3W of power

The LTC4292 / LTC4291 can supply up to 71.3W with one LAN cable.

As a result, the conventional PoE (12.95W to 25.5W maximum) can be supplied to industrial equipment, measuring instruments, and network equipment, while the conventional PoE can only be supplied to monitoring cameras and wireless access points.

LTC4292 / LTC4291 supports PoE++.

Backward compatible with traditional PoE

LTC4292 / LTC4291 supports the existing PoE standards, IEEE 802.3af and IEEE 802.3at.
This allows coexistence within a traditional PoE network.

PoE feed matrix
 

 The calorific value of concern is the lowest in the industry

Conventional switching hubs do not have much heat generation problems, but as PoE is introduced in recent years, heat generation has become a major problem.
In particular, PoE++ can supply a large current, so it is important to deal with heat generation.

However, the LTC4292 / LTC4291 uses an external MOSFET with low ON resistance and a 0.15Ω shunt resistor for each power channel to achieve the lowest heat generation in the industry.

Temperature range is - 40 to 85℃, suitable for industrial use

The LTC4291 and LTC4292 operate in a temperature range of – 40℃ to 85℃, so that industrial equipment can be used with confidence.

Minimal peripheral components, so low cost

While previous PoE designs required up to 6 photocouplers and a complex isolated 3.3V power supply, the LTC4291 / LTC4292 can communicate with each other over low-cost Ethernet transformers.

As a result, the cost of peripheral components can be greatly reduced, and reliability can be improved.

"DC2685B" Evaluation Kit for quick evaluation

Quick evaluation of LTC4291 / LTC4292 is available using the DC2685B evaluation kit.

Evaluation kit DC2685B

DC2685B consists of DC2684A-B (daughter card) and DC2683A (motherboard).

Overall connection diagram

The DC2685B Evaluation Kit enables you to begin evaluation immediately by connecting a LAN cable to the PC, DC2683A motherboard, daughter card and RJ45 port.

Up to 4 RJ45 ports can be connected for evaluation.
 

Target applications

• Industrial equipment and measuring equipment
• Network equipment（Server equipment）
• IP camera
• PoE -enabled appliances

Applications

Features of LTC4291/LTC4292

• 4 PSE ports
  2 power channels per port
• Fully compliant IEEE 802.3bt type 3/4 PSE
  Type 1 / 2 / 3 / 4 PD compliant support
• Low power consumption per channel
  Resistance of 150mΩ sensitivity
  30mΩ or low MOSFET RDS (ON)
• The chipset is insulated
  Eliminates need for Optos and 3.3V isolation
• Highly reliable multipoint PD detection
• Continuous, dedicated per-port power and current monitoring
  Per-port power monitoring
• 1MHzI2C compatible serial control interface
• Pin or I2C programmable PD (up to 71.3W power)
• 6mm × 6mm 40 pin QFN package（LTC4291）
• 4mm × 4mm 24 pin QFN package（LTC4292）