jaylar41
Electrical
- Aug 16, 2006
- 12
Hello,
I've got a little problem with a multi-layer ceramic capacitor that I'm trying to use. I'm using some as filter capacitors on a buck regulator circuit. The noise is filtered just fine, but it seems that too much current is conducting through them during their charge cycle (1st half of the arch on half sine wave). The voltage is fully rectified.
If I change the capacitor to an electrolytic, the current moving through it is attenuated significantly. I believe this is due to the larger ESR on the electrolytic, but when I physically add series resistance to the MLCC, the problem is only partially alleviated. The electrolytic is also polarized so that current can only travel one way. The ceramic capacitor, because it's non-polarized, is discharging straight to ground when it is supposed to be charging.
Why don't I use the electrolytic? Because the application doesn't not call for components that will freeze (or become too hot and explode for that matter). I'm trying to build everything without the electrolytic, period. There doesn't need to be a real nice voltage on the line, hence I don't need bulk capacitors. The line does need to be filtered though, and that's where the MLCCs come in.
My question is this: Is there a way to make my MLCC act more like an electrolytic besides adding a little ESR to it? Is there a way to make my MLCC polarized (add simple components in series, parallel etc...), such that current only travels one way through it?
This is my first time here, so I really don't know what to expect for responses. Any help would be greatly appreciated though. I will be happy to explain more if there's a need to. Thank you very much in advance.
Jason
I've got a little problem with a multi-layer ceramic capacitor that I'm trying to use. I'm using some as filter capacitors on a buck regulator circuit. The noise is filtered just fine, but it seems that too much current is conducting through them during their charge cycle (1st half of the arch on half sine wave). The voltage is fully rectified.
If I change the capacitor to an electrolytic, the current moving through it is attenuated significantly. I believe this is due to the larger ESR on the electrolytic, but when I physically add series resistance to the MLCC, the problem is only partially alleviated. The electrolytic is also polarized so that current can only travel one way. The ceramic capacitor, because it's non-polarized, is discharging straight to ground when it is supposed to be charging.
Why don't I use the electrolytic? Because the application doesn't not call for components that will freeze (or become too hot and explode for that matter). I'm trying to build everything without the electrolytic, period. There doesn't need to be a real nice voltage on the line, hence I don't need bulk capacitors. The line does need to be filtered though, and that's where the MLCCs come in.
My question is this: Is there a way to make my MLCC act more like an electrolytic besides adding a little ESR to it? Is there a way to make my MLCC polarized (add simple components in series, parallel etc...), such that current only travels one way through it?
This is my first time here, so I really don't know what to expect for responses. Any help would be greatly appreciated though. I will be happy to explain more if there's a need to. Thank you very much in advance.
Jason
