Isolated 8-port PoE PSE controllers eliminate optos to provide low cost solution
The LTC4290/4271 provides 8 independent PSE channels for simpler lower component count designs, reduced board space and ultimately reduced total solution costs. The LTC4271 provides a digital interface to the PSE host, whereas the LTC4290 provides the high voltage Ethernet interface; the two ICs are then bridged by an inexpensive Ethernet transformer. The transformer-isolated communication protocol replaces up to six expensive opto-couplers and a complex isolated 3.3 V supply used in traditional designs, resulting in cost savings and a more robust and easy to manufacture design.
The LTC4290/LTC4271 chipset earns a 100% interoperability score for PoE+ and PoE systems in popular compliance tests. When paired with the LT4275 PD (powered device) controller, complete end-to-end LTPoE++ systems can deliver up to 90 W while remaining fully compatible with PoE+ and PoE.
Users will appreciate the robustness provided by 80 V port pins and lowest-in-industry power dissipation, making thermal design easier than when designing with PSEs integrating more fragile normally-higher-RDS(ON) MOSFETs. PD discovery is accomplished using a proprietary dual-mode, four-point detection mechanism that ensures optimum immunity from false PD detection. Advanced power management includes prioritized fast shutdown, 12-bit per-port voltage and current readback, 8-bit programmable current limits and 7-bit programmable overload current limits, and field-upgradeable firmware. A 1 MHz I²C interface allows a host controller to digitally configure the IC or query port readings. C libraries are available to reduce NRE and improve time to market.
The LTC4290 is offered in three power grades: A grade uses Linear Technology’s LTPoE++ signaling to support 38.7 W, 52.7 W, 70 W and 90W PDs; B grade uses PoE+ signaling to support up to 25.5 W PDs; and C grade uses PoE signaling to support up to 13 W PDs.
All chipsets are offered in industrial temperature ranges. The LTC4290 is in a RoHS-compliant 40-pin 6 mm x 6 mm QFN package, while the LTC4271 is in a 24-pin 4 mm x 4 mm QFN package.
Pricing
The LTC4290/71 chipset is priced starting at $10.00 each in 1,000 piece quantities and is now available in production quantities. The LTC4290/LTC4271 is Linear Technology’s first 8-port PSE controller and complements the LTC4274 single port, LTC4266 4-port and LTC4270/71 12-port PSE controllers.
More information about the PSE controller at www.linear.com/LTPoE++
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