DC1561B

LTC4278 Power Over Ethernet Controller 5VDC Output Demonstration Circuit

is a demonstration circuit for LTC4278 integrated Powered Device controller and switching regulator intended for high power IEEE 802.3at and 802.3af applications. This board is a Type 2 IEEE 802.3at compliant, high power POE, PD. The DC1561B also features a wide auxiliary input voltage range of 9V to 57V. The board can connect to a Type 2 PSE device, such as the DC1567. The LTC4278 provides IEEE 802.3at standard PoE+ PD interfacing and power supply control. When the PD fully powers, the PD interface passes power from the PSE to the switcher through an internal, low resistance, high power MOSFET. The highly integrated LTC4278 controls a high power, small power supply that utilizes a highly efficient isolated flyback topology with synchronous rectification. It outputs 5V at 4.5A. DC1561B also demonstrates the use of an auxiliary wall adapter for nominal 12VDC, 24VAC/24VDC, or 48VDC systems. When present, the auxiliary supply is the dominant supply over PoE to provide power.

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Shutdown pin for flexible auxiliary power support

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Integrated state of the art no opto synchronous flyback controller

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Isolated power supply efficiency >92%

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88% efficiency including diode bridge and hot swap FET

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Superior EMI performance

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Robust 100V 0.7ohm Typ integrated hot swap MOSFET

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Integrated signature resistor and programmable class current

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Undervoltage, overvoltage and thermal protection

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Short circuit protection with auto restart

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Complementary power good indicators