Maintenance power signature controller at power interface of PoE system or PoDL system

摘要

The invention pertains to systems where DC power is supplied by a PSE (12) to a PD (18), such as over differential data wire pairs (14). IEEE standards require a minimum current to be drawn from the PD (18) in order for the PSE (12) to continue supplying the DC voltage. If the PD (18) is in a low power mode, the PSE (12) will normally discontinue supplying the DC voltage, which then requires a new detection and classification routine for powering up again. To avoid this, a "maintain power signature" controller (32) provides a periodic current pulse by a current source connected between the PD (18) input and the PD's full bridge rectifier (34, 36). Any droop in the DC voltage that reverse biases the full bridge rectifier (34, 36) while the PD (18) is in its low power mode will not affect the current pulse, so the PSE (12) continues to supply the DC voltage.