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High power application- multiple Keithley 2425's

Models 2400, 2401, 2410, 2420, 2425, 2430, 2440, 6430
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nheslop79
Posts: 1
Joined: April 28th, 2011, 9:46 pm
Country: Australia

High power application- multiple Keithley 2425's

Post by nheslop79 » April 28th, 2011, 9:57 pm

Hi there,

Was hoping someone could provide additional information or insight into using three keithley 2425's in parallel.
I have read through the HighCurrAppNote.pdf referenced in another post on these forums as a starting point.
(http://forum.keithley.com/phpBB3/viewto ... =13&t=1623)

In essence The Keithley 2425's are 20V, 3A -> 100V, 1A for 60W/100W max per unit.
Set up in parallel this would presumably allow for 20V, 9A - >100V, 3A for 180W/300W max total.

As I understand it, when operating in voltage source & in parallel, if we desire to sweep the range 0V - 100V that's a big drop from up to 9A at 20V to no more than 3A past 20V when operating with one unit in voltage source (FVMI mode) and the other 2 in parallel as FIMV.

The problem is that even though we would be measuring a DUT where current drops off as voltage increases it's quite likely that we would still have a current value > 3A for some period past 20V.

If instead we were to sweep current and measure voltage would that allow us greater leeway/higher power across more of the curve?
Quite happy to oversample current points & then provide something that looks like a standard IV curve...

Struggling to locate any means of having this work out due to the compliance voltage dropping to 20V as soon as any one of the units is above 1A.

Any advice welcome!

Vince W
Keithley Applications
Keithley Applications
Posts: 108
Joined: September 22nd, 2010, 12:27 pm
Country: United States

Re: High power application- multiple Keithley 2425's

Post by Vince W » May 22nd, 2012, 3:34 pm

I recommend using the 2651A source meter as it can source up to 10A at up to +/20V and 5A up to +/-40V. If you require a higher voltage range, we support using two in series (back-to-back) to achieve up to an 80V difference. With pulsing, this source meter can source up to 50A.

While it may be possible to parallel more than two 2425's, it is not something we directly support. If two 2425's are forcing current and the DUT fails open, the 2425 forcing voltage could be damaged. This is different from the scenario where one 2425 is forcing current in parallel with one 2425 forcing voltage as the current sourcing ability is only "one-on-one" with an instrument of the same capability. With three 2425's in parallel as you describe, the current sourcing ability is "two-on-one" which puts the voltage sourcing 2425 at risk.

As you mentioned, using three 2425's in parallel sourcing current from all would still encounter the voltage compliance limit of the selected current source range (and all three would have to be on the same range).

Vince W
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