Multiple port power supply system

1 . An apparatus for multi-port power delivery, the apparatus comprising:

a switched-mode power supply configured to:

receive an input AC voltage, and

produce a sequence of pulses of equal energy;

two or more ports at which power is to be delivered at DC voltages specified by corresponding devices connected to the ports for charging; and

time-division multiplexing circuitry configured to deliver, to the ports, power at respective levels that add to a maximum power corresponding to the sequence,

wherein the time-division multiplexing circuitry includes:

port-monitoring circuitry configured to monitor variations in power needs of corresponding ports, and

a multiplexer module configured to:

receive the sequence,

dispatch different integer numbers of pulses, as the sequence is being received, to corresponding ports in proportion to the respective power levels,

switch the dispatching of pulses from one port to another based on the monitored variations in the power needs of the corresponding ports, and

cause the switching to occur between the last pulse of each dispatch and the first pulse of the subsequent dispatch,

wherein the switched-mode power supply is configured to:

receive notification from the time-division multiplexing circuitry relating to an instant port to which pulses are being dispatched, and

modify production of the pulses of the sequence in compliance with the DC voltage specification for the instant port.

2 . The apparatus of claim 1 wherein:

the time-division multiplexing circuitry includes a current sensing circuit configured to determine zero-current crossings corresponding to the sequence of pulses,

the port-monitoring circuitry, for each port, includes:

a voltage sensing circuit configured to sense voltage at the port, and

a compensator circuit configured to:

compare the respective DC voltage specified for the port to its sensed voltage, and

produce a port-specific feedback signal indicative of the variations in power need of the port,

the multiplexer module, for each port, includes:

a switch configured to:

allow pulses of the sequence to reach the port when open, and

block pulses of the sequence from reaching the port when closed,

a comparator configured to compare the port-specific feedback signal with the feedback signals of the remaining ports, and

a latch configured to

cause the switch to be open or closed based on the comparison, and

synchronize each switching with an instantly determined zero-current crossing, and

the time-division multiplexing circuitry includes an OR-ing circuit configured to:

select from among the port-specific feedback signals the one corresponding to the port having its switch open, and

cause the switched-mode power supply to modify its pulse production based on the selected port-specific feedback signal.

3 . The apparatus of claim 2 wherein the OR-ing circuit comprises an array of low-current Schottky diodes in one-to-one correspondence with the ports.

4 . The apparatus of claim 1 wherein the switched-mode power supply includes a flyback converter.

5 . An AC/DC converter for universal serial bus (USB) power delivery (PD), the converter comprising:

the apparatus of claim 1 ,

wherein the two or more ports are USB ports.

6 . The AC/DC converter for USB PD of claim 5 wherein the AC/DC converter provides power sharing with respect to the two or more USB ports.