I am trying to utilise a Raspberry Pi's 5V output to push more current towards sensors connected to an MCP23017 i2c port expander. However, the MCP23017 requires that I down-convert the voltage to 3.3V.
To do convert from the Raspberry Pi's 5V supply to 3.3V, I'm using an LD1117V33 voltage regulator, a 100nF 16V ceramic capacitor, and a 10uF 16V electrolytic capacitor connected as shown in the diagram below.
- Pi's 5V output goes into the left pin of the LD1117V33, which connects to the the + (left) pin of the electrolytic capacitor.
- The middle pin of the LD1117v33 connects to the - (right) pin of the electrolytic capacitor, the left pin of the ceramic capacitor, and through to the ground.
- The right pin of the LD1117V33 connects to the right pin of the ceramic capacitor. It is supposed to output a 3.3V supply for the MCP23017 (but it does not).
- MCP23017 output connects to the ground.
- The ground in this diagram connects to the Pi's ground.
The MCP23017 works normally when connected to the Pi's 3.3V output. Why doesn't it work with the power regulator, shown above, connected to the Pi's 5V output?