This is a stabilised supply intended to be used with a bus powered USB hub in order to deliver a stabilised + 5 volt supply to the devices connected to it.
Due to the resistance of the connecting cable, and the resistances introduced for current sensing for overcurrent protection, the voltage at the hub can be anywhere between +4.5 V(loaded) and +5.5 V. This circuit will deliver a stabilized +5 V in both the cases, ie, it is a buck/boost design, using the TPS63000 switch mode regulator chip manufactured by Texas Instruments.
It can deliver +5 V at 500 mA from input voltages as low as 2 Volts so a rechargeable battery and its (USB powered) charger can be added to make this into a USB UPS for the USB hub.
Step 1: Preparing the circuit board
I decided to do a ground plane based layout. The chip has ten solder pads and a thermal pad to be soldered, and this was a different method to try with these types of leadless packages.
A scrap of single sided paper phenolic copper clad was cut to size and the outline of the chip drawn on its unclad side.
Then with a small screwdriver sharpened into a chisel, material was removed, making a niche for the chip to sit in.