The TPS23753A is a combined Power over Ethernet (PoE) powered device (PD) interface and
current-mode DC-DC controller optimized specifically for isolated converter designs. The PoE
implementation supports the IEEE 802.3at standard as a 13-W, type 1 PD. The requirements for an
IEEE 802.3at type 1 device are a superset of IEEE 802.3-2008 (originally IEEE 802.3af).
The TPS23753A supports a number of input-voltage ORing options including highest voltage,
external adapter preference, and PoE preference.
The PoE interface features an external detection signature pin that can also be used to
disable the internal hotswap MOSFET. This allows the PoE function to be turned off. Classification
can be programmed to any of the defined types with a single resistor.
The DC-DC controller features a bootstrap start-up mechanism with an internal, switched
current source. This provides the advantages of cycling overload fault protection without the
constant power loss of a pullup resistor.
The programmable oscillator may be synchronized to a higher-frequency external timing
reference. The TPS23753A features improvements for uninterrupted device operation through an ESD