Decoupling Capacitors
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Post Date:
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07/16/07
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Question:
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How do I have to proceed to implement the decoupling capacitors on a board designed with e2v-Grenoble device?
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Answer:
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There are two kinds of capacitors:
- The first ones are meant to filter out the low frequency noise coming from the power supplies. Consequently, they have to be implemented as close as possible to the power supplies connectors. There should be 1 couple of capacitors (polarized 10µF and non-polarized 0.1µF). - The second type of capacitors corresponds to the decoupling capacitors needed to remove the parasitics (supply ripples) induced by the signal switches. These capacitors (10nF and 100pF) should be implemented as close as possible to the chip. It is recommended to decouple as many power pins as possible and to solder the capacitors on the backside of the board, right under the device. If place is missing, you can short-circuit some pins that are close to one another and that have the same functions, and use only 1 couple of capacitors for this group of pins. Moreover, we recommend to stack the capacitors with respect to the following order: the 100pF should be under the 10nF capacitor. For example, in the case of the TS81102G0 DMUX package, T6, T7, U4, U5, U6 and U7 are VPLUSD pins and can be decoupled by only one set of capacitors. |

