Apparatus for remote wake-up during dedicated charging mode

An apparatus for remote wake-up during dedicated charging mode comprising:

• a USB transceiver port;
• a USB connector port;
• a switch network selectively coupling said USB transceiver port to said USB connector port;
• control logic coupled to said switch network and operative to control said switch network to disconnect said USB transceiver port from said USB connector port during a dedicated charger operational mode and to connect said USB transceiver port to said USB connector port upon detection of a potential remote wake-up condition to exit a sleep, standby or hibernate mode when a USB remote wake-up device is connected to said USB connector port;
• and
• signature detection circuitry between said USB connector port and said control logic to differentiate between USB devices to be charged and USB remote wake-up devices, said signature detection circuitry including a plurality of series connections of a comparator and a debouncer comprising
• (a) a first comparator having a positive input coupled to a D+ line of said USB connector port, a negative input coupled to a first reference voltage, and an output coupled to an input of a first debouncer, said first debouncer having an output,
• (b) a second comparator having a negative input coupled to a D− line of said USB connector port, a positive input coupled to a second reference voltage, and an output coupled to an input of a second debouncer, said second debouncer having an output,
• (c) a third comparator having a negative input coupled to said D− line of said USB connector port, a positive input coupled to a third reference voltage, and an output coupled to an input of a third debouncer, said third debouncer having an output,
• (d) a fourth comparator having a negative input coupled to said D− line of said USB connector port, a positive input coupled to a fourth reference voltage, and an output coupled to an input of a fourth debouncer, said fourth debouncer having an output, and
• (e) a bias resistor coupled between said D− line of USB connector port and ground.