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TPS2375-1

TPS2377-1

SLVS570 – MARCH 2005

The CLASS pin must not be shorted to ground.

disconnected when the line voltage exceeds this range to conserve power. This voltage range has been chosen

to allow detection with two silicon rectifiers between the controller and the RJ-45 connector.

VSS: This is the input supply negative rail that serves as a local ground.

RTN: This pin provides the switched negative power rail used by the downstream circuits. The operational and

inrush current limit control current into the pin. The PG circuit monitors the RTN voltage and also uses it as the

return for the PG pin pulldown transistor. The internal MOSFET body diode clamps VSS to RTN when voltage is

present between VDD and RTN and the Power-over-Ethernet (PoE) input is not present.

PG: This pin goes to a high resistance state when the internal MOSFET that feeds the RTN pin is enabled, and

the device is not in inrush current limiting. In all other states except detection, the PG output is pulled to RTN by

the internal open-drain transistor. Performance is ensured with at least 4 V between VDD and RTN.

PG is an open-drain output; therefore, it may require a pullup resistor or other interface.

VDD: This is the positive input supply that is also common to downstream load circuits. This pin provides

operating power and allows the controller to monitor the line voltage to determine the mode of operation.

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