Source vs. Drain

In the schematic for this motor driver, is the Source of MOSFET Q1 connected to Vin or Vout?

I'm trying to draw this up in Eagle Cad. I made the part, but all I'm sure of is the Gate is connected to pin 11.




It is a P-channel MOSFET with the source connected to Vin, Drain to Vout and gate to the chip.

The Pololu schematic is wrong in that they used the symbol for an N-channel MOSFET where they should have shown a P-channel.
If the MOSFET was really as shown, the inherent diode would always conduct. In a P-channel MOSFET, the internal diode points from the drain to the source, and the small arrow points outwards, not inwards.

In the symbol the substrate (middle bit) is connected to the source, not the drain.
The gate connection normally comes in at the source side too.

The arrow on the substrate points towards the gate for n-channel, away for p-channel (never
easy to remember).

Incidentally power MOSFETs are very different to logic MOSFETs (which are usually symmetric
between source and drain).