The TPS23757 is a combined Power over Ethernet (PoE) powered device (PD) interface and
current-mode dc/dc controller optimized specifically for isolated converters. The PoE interface
supports the IEEE 802.3at standard for a type 1 PD, which is equivalent to the 13W standard of IEEE
The TPS23757 supports a number of input voltage ORing options including
highest voltage, external adapter preference, and PoE preference.
The TPS23757 has an output flag indicating if an external wall adapter is active when
used in conjunction with ORing controls. The detection signature pin can also be used to force
power from the PoE source off. Classification can be programmed to any of the defined types with a
The dc/dc controller features two complementary gate drivers with programmable dead time.
This simplifies design of highly-efficient flyback topologies or active-clamp forward or flyback
converters. The second gate driver may be disabled if desired for single MOSFET topologies. The
controller also features internal softstart, bootstrap startup source, current-mode compensation,
and a 78% maximum duty cycle. A programmable and synchronizable oscillator allows design
optimization for efficiency and eases use of the controller to upgrade existing power supply
designs. Accurate programmable blanking, with a default period, simplifies the usual current- sense
filter design trade-offs.
The TPS23757 has a 9 V converter startup, permitting operation with 12 V wall