DC917A

DC917A demonstration circuit is a PoE to 3.3V at 2.6A isolated converter featuring the LTC4267CDHC. The board provides a complete IEEE 802.3af power device (PD) interface and isolated 3.3V power supply solution for use in Power over Ethernet (PoE) applications in a very small printed circuit board footprint. The LTC4267 integrates the 25kohm signature resistor, classification current source, thermal overload protection, signature disable and power good signal along with an undervoltage lockout optimized for use with the IEEE required diode bridge. The precision dual level input current limit allows the LTC4267 to charge load capacitors and interface with legacy PoE systems. The LTC4267 combines the above features with a current mode switching controller designed for driving a 6V rated N-channel MOSFET. It features programmable slope compensation, soft-start, and constant frequency operation, minimizing electrical noise even with light loads.

• Turn-on voltage of -37V (input from PSE)
• Maximum turn-off voltage of -31V (input from PSE, PD switch turns off)
• Minimum operating voltage of -33V at IOUT = 2.6A
• Power converter input operating range from -37V to -57V at VOUT=3.3V, IOUT = 0 to 2.6A
• Maximum input current of 375mA, typical (input from PSE, PD high level current limit)
• Maximum output current of 2.6A at VOUT=3.3V
• Output voltage of 3.3V, typical at VIN=48V DC from PSE, IOUT=2.6A
• 2% line (0% to 100% full load) and 2% load (0% to 100% of rated full load) output regulation