Connecting OSCONs in series for high voltage.

[Fanuc]

Hello,

I was wondering if anyone had experience connecting Sanyo's excellent OSCONs in series. The problem with these and other solid electrolyte (such as polymers etc) is they are electron conductive types rather than ionic conductive like Wet types electrolytics.

The OSCONs have fantastic ESR/impedance specs out to 100's of khz's. Most low impedance "wet" types are no where near plus there unaffacted by low temperature and last alot longer.

Best electrolytic available is the speciality polymer 4 terminal from panasonic but these are low volts/capacitances and are surface mount.

I have read when connecting large smoothers in series that the dividing resistance should be 1/10th of the leakage current resistance. Presumably to minimize heating effects.

I was thinking a 4x 1000uF 16v OSCON bypass cap (making a 250uF 64v OSCON ) would be superb but it's knowing how to do it. OSCON's have rapid inrush current compared with Wet types also. I reckon it's dividing the heating issue that is the problem personally.

Any advice/experiences welcome

Kevin

[weissi]

'think if you need high voltage, use EPCOS Sikorel... They're fantastic also and also expensive as OSCONS

[Fanuc]

Originally posted by weissi
'think if you need high voltage, use EPCOS Sikorel... They're fantastic also and also expensive as OSCONS

Yeah I know of the Siemens Sikorels, they are indeed fantastic caps for power supply duties in terms of ripple current to capacitance ratings. But at LF.

However they are no match at 100Khz+ to the OSCONs and it was this I was thinking off. As a good HF bypass. I have heard of people putting films with say Or1 resistances in series to mimic it's effects but I don't think there comparable.

Kevin

[weissi]

The question maybe is stupid: Which HF device do you think of runs on voltages as high as 64 V? Do you plan to build a high-end Radio transmitter ?

Markus

[Fanuc]

Originally posted by weissi
The question maybe is stupid: Which HF device do you think of runs on voltages as high as 64 V? Do you plan to build a high-end Radio transmitter ?

Markus

I was planning on maybe using them for a variety of apps. such as in power amplifier supply line decoupling etc.

Remember power amps bandwidth goes out to many Mhz's if not 10's of Mhz's.

I cannot remember the exact figures, but an OSCON in the 100khz - 400Khz region in frequency would need something like 20-50 more capacitance in equiv. "wet" type electrolytics to equal the performance in impedance. To be honest, I am reciting this from memory - but it was something stupid like that.

Now that I am thinking about it, I think they may need _active_ voltage division. The voltage dividers done with R's take too long to share the voltage.

Sounds like we need some shunt transistors etc. The real difficulty with voltage sharing arrangements is retaining as much of the performance (low Z) as possible. I might have to badger Sanyo's technical department about this.

Kevin

[nonoise]

Hi we used the "FM" series caps from Panasonic
In SMPS applications with a 1uF 50V X7R SMD cap in parallel
They worked very well indeed especially if you construct a parallel array of them.
We use a 100uF 50v device 0.061 Ohm Impedance @(100kHz)(+20°C)

You could maybe use 820uF 50V which is only 0.014 Ohm or the more popular size of 1000uF 50V 0.016 Ohm. (The 820uF is taller, explaining the better ESR value)

The ceramic cap is the magic bullet in this equation, but if you are really concerned about the very lowest impedance at high frequency
then the board layout becomes just as important.

[jean-paul]

Originally posted by Fanuc
I have heard of people putting films with say Or1 resistances in series to mimic it's effects but I don't think there comparable.

Kevin

Fanuc, sorry for bothering about unimportant stuff but is this new spelling of some kind to write "they are" as "there" instead of "they're" ?