How important are low ESR capacitors? When is it necessary to use them and why?
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Re: How Important are Low ESR Capacitors
Low-ESR capacitors are essential in switching power supplies (including DC-DC converters).
For the primary side 200/250/350/400/450V unit(s), you can usually get away with a standard (preferably high ripple rating) unit.My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics. -
Re: How Important are Low ESR Capacitors
What are switching power supplies? When are they used and why?
Thanks! What are primary side units?Comment
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Re: How Important are Low ESR Capacitors
No offense but the questions you're asking are so simple they have answers in Wikipedia and Google.
Electronics often work with low voltage, which is 1.8 , 3.3v, 5v, 12v ... to put it in comparison a simple AA battery has 1.2-1.5v
The socket on the wall in your house has around 110v and in other countries the sockets have 230v
Chips can not handle that much voltage so there has to be a device to convert this 110-230v to those lower voltages in a way that would also make the devices safe for humans.
Transformers take care of the safety factor and they're the main way of obtaining lower voltages from high voltages. You can read about them here: http://en.wikipedia.org/wiki/Transformer
Basically, the "primary" in a power supply is the part of the power supply where there can be high voltage. The secondary side is the part that has only low voltages and safe ones.
So by primary side "units" he meant the capacitors rated for high voltage.
The simplest power supply possible is made out of a transformer and a bridge rectifier which converts the low voltage AC current generated by the transformer into DC voltage.
A switching power supply is a type of power supply that converts high voltage (100-400v) into lower voltages by sending pulses of electricity through a somewhat special transformer.
Depending on how much power is demanded by the devices attached to the power supply, the controller (a kind of basic processor) inside the power supply adjusts the length of those pulses to send more current on the other side.
So several thousand times a second the controller checks how the voltage is on the output and tries as best as it keep to keep it steady by shrinking or extending those pulses of electricity through the transformer.
Capacitors and inductors are used on the secondary side to smooth out the voltages. They have to be Low ESR because put in a very simple way, esr is a propriety of capacitors, something which makes it hard for that controller to work properly and produce good low voltages.
Ideally, you'd want linear power supplies to generate low voltages for the computers. However, this is not possible because the transformers inside the power supply would have to be very big and heavy... think the transformer alone being as large as 2 DVD drives. Switching power supplies are used because it's possible to use special transformers that are small and light.
You can read more about switching power supply here: http://en.wikipedia.org/wiki/Switched-mode_power_supply
And you can read more about all kinds of power supplies, including the simple ones here: http://en.wikipedia.org/wiki/Power_supplyComment
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Re: How Important are Low ESR Capacitors
Thanks! I read that Wiki article before and didn't understand a lick of it. But you pretty well answered my questions in a simple paragraph. Wkipedia needs more of the "human element", I think. Will go back and see if I get it now.Comment
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Re: How Important are Low ESR Capacitors
What is "impedance ratio"? I keep seeing it on datasheets but it gives me no real info on what the ESR is? How do I know what the ESR is from "impedance ratio"?
Example:Comment
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Re: How Important are Low ESR Capacitors
No offense, but I can change wikipedia in two seconds.Comment
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Re: How Important are Low ESR Capacitors
It's not a term I'm familiar with but I assume it's about how much impedance changes when the capacitors are working at a temperature different than the one in the rating.
The datasheet says :
Impedance Ratio
ZT/z20 (MAX.)
and you have there :
So that simply means that the at -25c the impedance for a 6.3v capacitor is 4 times the impedance at 20c.Code:Rated Voltage(V) 6.3 10 16 25~100 160~250 350 400 Impedance Ratio Z-25℃/Z+20℃ 4 3 2 2 4 4 6 Z-40℃/Z+20℃ 8 6 6 3 6 8 10 T/z20 (MAX.)
At -40c, the impedance is 3 times the impedance of a 25-100v rated capacitor.
That's just an assumption, like I said, I'm not familiar with the term.
This series of capacitors you linked to is general purpose, it's not Low ESR or specialty, so the impedance and ESR are not important, hence why they're not even listed in the datasheet.Comment
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Re: How Important are Low ESR Capacitors
Okay, thanks a lot.
so it's a pretty safe assumption That if ESR isn't listed, then it's not a low ESR capacitor.
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Re: How Important are Low ESR Capacitors
I agree. I've been contributing to Wikipedia for over seven years in all kinds of topics, and I've found it to be a very political environment. Edit wars go on frequently behind the scenes and editors with better ideas and balanced approaches to topics often get driven out or simply leave in disgust. That said, I still use it as an entry point, particularly technical/computer topics, because the articles define terminology and provide links where one can learn more. In that sense sites like Wikipedia are not much different than traditional printed and bound encyclopedias.Comment
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Re: How Important are Low ESR Capacitors
Wikipedia is very useful for electronics engineering, including theory and practical elements. It can be inaccurate, but so can reference manuals and books. Unlike reference manuals and books, it can be corrected essentially instantly.
The most important rule with electronics is to take care and understand the risks. No internet article should be trusted with this.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Hi,
Back after a long hiatus with some old power supplies that need repairing. I've recently picked up a couple of 386SX systems, two 486DX systems, a SiliconGraphics Indy and an iMac G3 that either have verified leaking capacitors in their power supplies, or are likely to in the near future. For the sake of simplicity, instead of tackling all at once, I'm starting with the 386's and one of the 486's.
The 386's power supplies are Seasonic SS4040A's, with caps that are visibly leaking, and 9 replacement caps per unit are required. Most appear to be from the Rubycon... -
What is important to know about capacitors on the motherboard?
If you replace a new capacitor:
Can the size of the capacitor be larger or smaller than the original?
What values are important to be exactly the same as the original uf, a, v, ohm?
I mean laptop and smartphone motherboards. -
hey all, iv got my favourite battery charger here which iv had for many years probably 15 years now or maybe even more. it still works good but thought id open it up to clean the dust out of it, lots of dust inside but now its clean and noticed 4 capacitors inside it and wondered if i should replace them.
it has inside:
2 x 47uf 16v caps 105c branded as Su'scon (lol sounds sus to me)
2 x 470uf 16v LZ105c branded as G.Luxon
not heard of these brands are they any good?
iv attached photos of the charger and the board inside for an idea on the type of... -
I did not have any 27uf @ 50 volt capacitors but one nice thing is that it has enough room for two capacitors in parallel a 22uf and a 4.7uf @ 50 volts 22 plus 4.7 equals 26.7uf which so very close to 27uf I will show some pictures of it sometime tomorrow
This is one of the shit est boards I seen in a very long time and it was the daughter board the traces just lifting off the board I had to use the capacitor leads to repair the the traces and the main board is not any better because I had to repair several traces for the daughter board to the main board
After all of... -
Greetings! I have this ERP650-PS atx power supply, it is a relatively simple psu, the primary has a driver IC that controls the two main mosfets (two 20n60S5), together with a Classic Standby circuit with a PWM IC (not a FET like the VIper22A) , relatively similar to the SDC606P.
The whole point is that I got this power supply years ago when I had no knowledge, apparently the PWM IC was burned because someone turned the power supply on with the switch at 110v in a 220v network (classic error). Important detail: the power supply at the time came without the primary capacitors.
...
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