Power management device for immediate start-up during power negotiation

An energy management device coupled to a power supply device, which is operable in a device detection mode where the power supply device periodically applies a voltage between a first threshold and a second threshold over a determined time period to detect a connection status of load devices, and in a power supply mode for providing power to load devices wherein the voltage is above the second threshold, and coupled to a load device operable in accordance with a predetermined power-acceptance criterion, in either an accepting operational state or a non-accepting operational state with respect to receiving power from the power supply device, the energy management device comprising:

• an energy buffer,
• a buffer controller, wherein the buffer controller is configured to detect that the load device is in the accepting operational state and the voltage provided by the power supply device has dropped below the second threshold and is between the first threshold and the second threshold, and to connect the energy buffer with the load device responsive to detecting that the load device is in the accepting operational state and the voltage provided by the power supply device has dropped below the second threshold and is between the first threshold and the second threshold, and to maintain connecting the energy buffer with the load device for a predetermined time after the voltage provided by the power supply device has dropped below the second threshold.