??? 02/16/09 20:42 Read: times |
#162494 - Depends... Responding to: ???'s previous message |
There's no rule about how many decoupling caps you need in a circuit. It always depends on the level of noise you want or must tolerate.
In digital circuits you should decouple each chip by a 100nF/X7R cap, with shortest leads to the supply pins. Each group of 5...10 chips should get a 2.2...10µF electrolytic. Add a 10...47µF electrolytic at the terminal where the supply voltage enters your board. If high currents are to be driven, use an additional 10...47µF electrolytic, as I have shown you. All the decoupling is to minimize the noise on Vcc and ground. Kai |