Electronic – arduino – What does it mean when components in schematics do not connect

arduinobreadboardintegrated-circuitschematicssd

I'm fairly new to the whole Arduino world, and I'm just really curious about this schematic that I came across… I can read the basics of a schematic, but this one has me puzzled. What are the integrated circuits down at the bottom that aren't connected to anything?

How do you know where they go in the circuit? This is the schematic for the Adafruit MicroSD breakout board.

Best Answer

IC1 has six sections (A-F) although only 4 are used the circuit.

In general it is not allowed to leave inputs of CMOS devices unconnected so the two at the bottom show what to do with the inputs, connect them to ground. Section E also shows how the connections for the power supply pins of the entire device. The outputs are not used and so are shown as unconnected.

If you did leave the inputs of sections E and F unconnected they could cause incorrect operation of the sections that are used (A-D).

kevin