How to use the YwRobot Power Supply to obtain 3.3V from a 5V source.
All the tests have been performed with
- YwRobot Breadboard Power Supply MB V2 (MB102)
- Arduino Uno board (or any external 5V source)
The documentation on the YwRobot board is not abundant as other pieces of electronics around. It features two AMS1117 adjustable regulator (rated at 1A) in cascade: the first stage provides the 5V starting from the input voltage (in the 6-15V range), the second stage feeds the 3.3V rail stepping down from the 5V rail.
See equivalent LDO voltage regulator REG1117 from Burr-Brown (Texas Instruments)
Connect the rails
To achieve the 5V to 3.3V conversion only the second stage of the board is used. In this slightly unconventional configuration the main input is not used (as well the first stage 5V linear regulator) and a 5V source is connected to a 5V pin to feed just the second AMS1117 to provide 3.3V.
The pictures show how to set the jumpers to have a rail-to-rail conversion where one side of the board (input) taps into the breadboard 5V rail, and the other side feed the opposite rail at 3.3V.