Attiny25/45/85 FW Development Thread

Not sure which specific driver you are referring to, or which capacitors (there are no ‘input’ / ‘output’ capacitors on these drivers).

Most sub-circuits need a decoupling capacitor, which is simply a kind of near-and-ready voltage source. The MCU should have one, located very close to it. On most drivers this is C1. On many drivers C1 is separated from the MCU by D1. In that case you should add a second capacitor C2 very close to the MCU.

On most drivers C1 is also decoupling the FET/emitter, making it almost useless (actually detrimental) for the MCU. Enter the added low-value resistor R5 to isolate the FET/emitter from C1 and the MCU. (A ferrite bead would actually be a more more appropriate part to use here, but can add complications if not selected correctly). For our purposes you can easily get away without C2 when you have this resistor.