Calculating the input current drawn by a MOSFET driver
Correct -- the spec to look for is the input-bias current of the parts you are trying to drive, and in this case, the datasheet specifies they are 10uA each. I initially thought that indicated BJTs, but the datasheet makes it clear they are FET input stages (high impedance).

Assuming your PIC is running at 3.3V, those 100R resistors will be fine and not affect the ability of your device to source the current required for the drivers. From a DC point-of-view, I think you are OK.

Here is the thing that wigs me out about that circuit schematic though -- you are driving a relatively low frequency signal into six separate devices in a fan-out configuration. It appears the rise-time of the PIC outputs are fairly slow:



And the total input capacitance of the devices you're driving appears to be 2pF * 6 = 12pF + some stray trace capacitance which still puts you (probably) under 20pF. How long are the trace lengths we are talking here? There is the possibility (unlikely with how slow those drivers are) of getting reflections which could lead to double-triggering those drivers, though they do have Schmitt triggers to improve noise-rejection / tolerate slow-rising signals.

The safest thing to do IMO is to buffer the signal to drive all six drivers, but if you can prove via design that it's not necessary to do so due to the way you layout the traces (fly-by routing with small stubs, for instance), that's also fine and you'll save on BOM cost and part count.

You should answer (since I can't tell from your provided info yet):


Is there any possibility I'm going to end up with more than 25pF (or so) of capacitive loading?
Does my PCB layout result in a trace with long stubs or otherwise weird routing that requires me to consider the rise-time / reflections occuring?