DC-DC conversion.
The bq51013AEVM-765 Receiver pumps out 5 volts at a maximum of 1 ampere. In other words, a maximum of 5 watts of power.
This is ideal for USB power substitution and for powering "vintage" digital logic based logic devices that have a VCC of 5V.
Stepping up to the plate
However, many battery powered items do not operate at 5 volts so to use the receiver with them some sort of DC-DC conversion is required.
For my initial experiments I have used a Texas Instruments TL499A Wide-Range Power-Controller that I had in my laboratory.
The TL499A is a step-up switching power supply controller capable of a maximum of about 900mW (9V @ 100mA from a 5 volt input).
This part can accept an input between 1-10 volts and output up to 30 volts.
The output voltage is selectable by adjusting just one of its feedback resistors. I've used a 50k trimpot in series with a 10k fixed resistor for testing.
For more information on this part look at http://www.ti.com/product/tl499a
The TL499A is sufficient for initial proof of concept testing but I will need to resort to more powerful to make full use of the available power.
Texas Instruments has a comprehensive suite of DC-DC converters.
Just stepping below for a while
For low power step down applications a Zener diode and series input resistor can be used.
I've used a 4.7v 1W Zener and 10 ohm resistor for applications that normally operate with 3 x 1.5 cells.
The Zener diode (in parallel with the load) regulates the output voltage with the excess power is dissipated by the 10 ohm resistor with the remainder of the power dissipated through the Zener diod and load.
It's not ideal but very quick to set up.
For 3.3 volt applications I often use the versatile LM3940ISX-3.3/NOPBLM3940ISX-3.3/NOPB 5V-3.3 volt Low Dropout Linear regulator (http://www.ti.com/product/lm3940).
Like the Zener diode and series input resistor solution it too dissipates the excess power as heat.
It handles an output current of 1A.