25 Jun 2018
Isolated 4-port PoE++ PSE controller delivers up to 71.3W
Analog Devices announces the Power by Linear LTC4291/LTC4292 isolated 4-port power sourcing equipment (PSE) controller chipset designed for use in IEEE 802.3bt (PoE++) Power over Ethernet (PoE) systems.
The LTC4291/LTC4292 provides 4 independent PSE ports comprised of 2 channels each, ensuring fully compliant support for the next generation of IEEE 802.3bt powered devices (PDs). The LTC4291 includes a digital interface to the PSE host, while the LTC4292 implements the high voltage Ethernet power interface. The two ICs intercommunicate using an inexpensive Ethernet transformer. The transformer-isolated communication protocol replaces up to six expensive opto-couplers and a complex isolated 3.3V supply used in traditional designs, resulting in significant BOM cost savings and a more robust and easy to manufacture design.
The LTC4291/LTC4292 chipset operates seamlessly with compliant 802.3bt PD controllers, the LT4294 or LT4295, forming complete end-to-end PoE++, PoE+ and PoE solutions. Up to 71.3W of power can be delivered to single-signature or dual-signature PDs. Users will appreciate the robustness of the 80V pins. Analog Devices is a specialist in low power path dissipation, significantly outperforming PSEs that integrate higher RDS(ON) MOSFETs.
PD discovery is accomplished using a multipoint voltage and current detection mechanism, ensuring the best immunity from false PD detection. Advanced power management includes Autoclass support, prioritized fast shutdown, 14-bit per-port power and current readback, 8-bit programmable power limits and 7-bit programmable overload current limits. Systems can be updated with field-upgradable firmware. A 1MHz I2C interface allows a host controller to digitally configure the chipset or query port status. Power management “C” demonstration libraries are also available to reduce NRE and improve time to market.
The LTC4291/LTC4292 chipset is offered in the industrial temperature range. The LTC4291 digital controller is in a RoHS-compliant 24-pin 4mm x 4mm QFN package, while the LTC4292 analog controller is in a 40-pin 6mm x 6mm QFN package. The LTC4291/LTC4292 is Analog Devices’ first 802.3bt PSE controller and provides an upgrade path from the LTC4266 4-port 802.3at PSE controller.
Summary of Features: LTC4291/LTC4292
Four PSE Ports
Two Channels per Port
Fully Compliant IEEE 802.3bt Type 3 & 4 PSE
Compliant Support for Type 1, 2, 3 & 4 PDs
Chipset Provides Electrical Isolation
Eliminates Optos & Isolated 3.3V Supply
Low Power Dissipation
0.15Ω Sense Resistance per Power Channel
Enables Extremely Low RDS(ON) External MOSFETs
Very High Reliability Multipoint PD Detection
Connection Check Distinguishes Single-Signature & Dual-Signature PDs
Continuous, Dedicated Per-Port Power & Current Monitoring
1MHz I2C Compatible Serial Control Interface
Pin or I2C Programmable Max PD Power up to 71.3W
40-Pin 6mm x 6mm (LTC4292) & 24-Pin 4mm x 4mm (LTC4291) QFN Packages
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