SN74AHCT1G125: Bypass capacitor

Hello Tadahiko-san,

Having multiple supply pins means that you'll be adding more capacitance. Our default recommendation for a bypass capacitor on a single supply device is 0.1uF. For a multiple supply device, we recommend 0.01uF or 0.022uF. For example, if you have a device that has 4 supply pins with 0.022uF bypass capacitors, then that would add up to 0.088uF of capacitance, which is getting close to the 0.1uF recommendation for a single supply device. The value is just more distributed in this case.

Just because the datasheet recommends a 0.1uF bypass capacitor doesn't mean that you have to use that value. In fact, most systems will benefit from spending time selecting a specific bypass capacitor (or capacitors) for your application. We don't know exactly how your system is designed, or what capacitors you have available to you.

I think this is an interesting topic, so I'm going to work on writing up an FAQ to post regarding selecting a bypass capacitor. Thanks for the idea!