DC2046A-A

DC2046A-A demonstration circuit is an Ethernet Alliance™ certified PoE powered device with an isolated power supply using synchronous flyback topology, featuring the LT®4276 and ideal diode bridge controller (LT4321). The LT4276 provides IEEE802.3af (PoE, Type 1), IEEE802.3at (PoE+, Type 2), and LTPoE++™ PD interfacing and power supply control. When the PD is fully powered, the PD interface switches power over from the power sourcing equipment (PSE) to the switcher through an external, low resistance, high power N-channel FET. The highly integrated LT4276 controls a high power, small sized power supply that utilizes a highly efficient flyback topology with synchronous rectification. The LT4321 provides further efficiency improvement by minimizing the bridge losses. The DC2046A-A supplies a 3.3V output at up to 6.8A. It also demonstrates the use of an optional auxiliary power supply input of 48V. When present, the auxiliary supply becomes the dominant supply over PoE to provide power.

• 25mVP-P (typ) output voltage ripple (VPORT = 42.5V, IOUT = 6.8A)
• 90% (typ) efficiency (VPORT = 50V, IOUT = 6.8A, end to end)
• 250kHz switching frequency