SMPS capacitors

[news.carnet.hr]

I want to build SMPS for car audio but I cant find capacitors with low ESR
(Eq. Seriall Resistance) where I live. So the question is can I put few
(5-10 how much) litle capacitors in parallel and make this ESR lower. Sory
for my bad English and thanks for answer.

 

[Ken Smith]

In article <cj2gaa$c77$1@bagan.srce.hr>,
news.carnet.hr <someone@microsoft.com> wrote:

I want to build SMPS for car audio but I cant find capacitors with low ESR
(Eq. Seriall Resistance) where I live. So the question is can I put few
(5-10 how much) litle capacitors in parallel and make this ESR lower. Sory
for my bad English and thanks for answer.

You didn't say what capacitance you needed nor the frequencies involved.
You may be able to get a low enough ESR using ceramic capacitors.

Since you are building it for car audio I can assume it is a boosting
supply, Some topologies are much kinder to the capacitors than others.
In the classic flyback booster, the output capacitor is the one that
really needs the low ESR value.

If you make the flyback design's inductor a transformer so that the
transistor's duty cycle is about 50%, you can use a much higher ESR than
with a lower duty cycle.


--
--
kensmith@rahul.net forging knowledge

 

[Rich Grise]

On Friday 24 September 2004 06:33 pm, Ken Smith did deign to grace us with
the following:

In article <cj2gaa$c77$1@bagan.srce.hr>,
news.carnet.hr <someone@microsoft.com> wrote:
I want to build SMPS for car audio but I cant find capacitors with low ESR
(Eq. Seriall Resistance) where I live. So the question is can I put few
(5-10 how much) litle capacitors in parallel and make this ESR lower. Sory
for my bad English and thanks for answer.

You didn't say what capacitance you needed nor the frequencies involved.
You may be able to get a low enough ESR using ceramic capacitors.

Since you are building it for car audio I can assume it is a boosting
supply, Some topologies are much kinder to the capacitors than others.
In the classic flyback booster, the output capacitor is the one that
really needs the low ESR value.

If you make the flyback design's inductor a transformer so that the
transistor's duty cycle is about 50%, you can use a much higher ESR than
with a lower duty cycle.

For something like this, wouldn't an ordinary square wave/step-up

transformer be a "better" choice? Is that called a push-pull forward
converter?

Thanks,
Rich