Timeline for Does my circuit need decoupling caps?
Current License: CC BY-SA 3.0
11 events
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| Nov 18, 2013 at 8:46 | comment | added | abdullah kahraman | This is a good answer. +1. Never thought of adding decoupling caps across [switched element + switching device]. | |
| Nov 18, 2013 at 3:46 | comment | added | Michael Karas | Keep in mind that capacitors are low cost, usually quite small, and easy to work into an initial layout. If one takes the mindset that the "circuit is simple" or "why would I add the cost" and then leaves out the bypass capacitors they can require a full redesign to get them properly integrated into a circuit after the fact. | |
| Nov 18, 2013 at 3:43 | comment | added | Michael Karas | @DavidHögberg -- The decoupling capacitors serve as a low impedance source to supply current or suck up current right at the time there is a fast switching transient on the nodes that the capacitor is connected to. This helps to keep the voltage stable rather than the switching transient causing excess voltage excursions on the voltage rail or GND bus. They need to be as close to the transient load as possible to do the most good. Without a capacitor a node with a transient could have a voltage droop serious enough to upset the operation of the nearby components. | |
| Nov 18, 2013 at 0:29 | vote | accept | David Högberg | ||
| Nov 17, 2013 at 22:21 | history | edited | jippie | CC BY-SA 3.0 | added 254 characters in body |
| Nov 17, 2013 at 22:12 | history | edited | jippie | CC BY-SA 3.0 | added 13 characters in body |
| Nov 17, 2013 at 22:03 | history | edited | jippie | CC BY-SA 3.0 | added 75 characters in body |
| Nov 17, 2013 at 21:54 | history | edited | jippie | CC BY-SA 3.0 | added 75 characters in body |
| Nov 17, 2013 at 21:48 | history | edited | jippie | CC BY-SA 3.0 | added 249 characters in body |
| Nov 17, 2013 at 21:47 | comment | added | David Högberg | I pulse one of the LEDs using PWM. I assume from your post that using a capacitor for that LED would be a good idea. What is the reason for that though? I.e. what could happen if I don't have that cap? | |
| Nov 17, 2013 at 21:42 | history | answered | jippie | CC BY-SA 3.0 |