power supply (can I set it to regulate current to operate in addition to voltage regulation)

[yefj]

UPDATE: sorry i forgot to complete the title and now i cant edit it.

Hello,I have the E3640A power supply need it to function as a current source .
in regular power supplies we set the maximum limit current and the regular voltage we want to output.
In the manual shown in the link there is just setting the maximal limit values, there is no option for setting the current we want to output.
How can i use it as a current source?
Thanks.

E3640A-E3649A Programmable DC Power Supplies

This technical specifications sheet contains key benefits and features of the E3640A/41A/42A/43A/44A/45A/46A/47A/48A/49A programmable dc power supply. It also includes specifications, product photos, and ordering information. MODEL #s: E3644A E3645A E3646A E3647A E3648A E3649A

www.keysight.com

 

[FvM]

In the manual shown in the link there is just setting the maximal limit values, there is no option for setting the current we want to output.

The datasheet doesn't talk about current "maximum limit value", just about programming voltage and current. Seriously, I don't know what I don't know which difference you expect between current setpoint and limit value. It's basic constant U / constant I regulation. The output is controlled so that both values are not exceeded.

 

[yefj]

Hello FVM , I want a constant current on my load .
I am used to set power supplies as voltage sources .
In a voltage source case , we set voltage and the current value depends on the load .


What am I missing when thinking of it as a current source .
Because as I see it , it could choose to put the voltage and current will be different .
Could you please give me an intuition?
Thanks .

 

[yefj]

Hello,I have found the manual.
They say to go to the limit section and set the maximal voltage and current values.
So how it makes it constant current device?
We just set the maximum for both of them.
where am i going wrong with the logic?
Thanks.

 

[G4BCH]

Set the voltage to maximum and the current to your constant current value. Connect our load and the power supply will do it's best to be a constant current source. If the load resistance is too high there may not be enough voltage to supply the required current. In that case you need a different power supply. Check that you do not exceed the dissipation in the supply.

 

[vfone]

I think the answer is in points 3 and 4 (above the ones you posted).
CC (constant current) mode can be easily verified varying the load resistance and measuring the current, which should remain constant.

 

[yefj]

So in this device we set the maximal values for current and voltage.
but how do i make it a current source and not voltage source?
Thanks.

 

[dick_freebird]

You should consider the voltage setting to be the
"voltage compliance limit" and the current setting to
be the "current setpoint".

It's best to not set voltage to front panel max, but rather
to pin max voltage. More voltage can allow flyback events
to punch out gate oxide if there's much inductance or the
voltage control loop is slow to cap it off (or, lacks sink
capability altogether). And to that point you may want a
shunt resistor on source, to make sure there is -some-
sink capability and de-embed its contribution later.

It's easy to play with the settings and a meter on the bench
and get an understanding. Hard knocks for the rest. Like
the flyback thing, I saw ruining one of my parts sporadically
at test when a wide open voltage compliance and a forced
10mA current met a marginal socket connectivity and the
current "found its own way out". So I generally prefer force
voltage, measure current, with current compliance set sane.

 

[FvM]

but how do i make it a current source and not voltage source?

The power supply isn't specifically a voltage source. As most lab supplies it can act as both, voltage source and current source. Current and voltage setpoint and load characteristic decide in which mode it operates.

 

[crutschow]

how do i make it a current source and not voltage source?

A supply is always both, depending upon the settings.
It will supply a constant voltage output at it's voltage setting until the load is low enough to reach the current setting, at which point it becomes a constant-current output.
That's how all constant-current circuits work.
How would you expect it to operate differently?

 

[KlausST]

Hi,

I guess the problem is "the wrong expectation".

The setup is basically the same for both.

If you want V regulation, set V to the desired value and set I to max. (= constant voltage)
If you want I regulation, set I to the desired value and set V to max. (= constant current)

So basically the question is:
* what do yo exect?
* and what is not like expected?

Klaus

 

[volker@muehlhaus]

I guess the problem is "the wrong expectation".

I agree. It seems that yefi wants to enforce a certain current and voltage, and ignore that V=R*I still applies.

 

[yefj]

Hello Volker,that was my problem exactly ignoring Ohm law
i needed to increase voltage to handle a big resistor .
Thanks.

 

[KlausST]

Hi,

now where do you see the difference to the "voltage regulation"?

--> You also have to follow Ohm´s law. If you set the current limiter for a too low value .. it will not work as voltage source either.

Klaus

 

[D.A.(Tony)Stewart]

As long as the apparent voltage does not exceed CV it will remain in CC mode where impedance Z= R+jX and apparent vector magnitude is |Zo|=sqrt(R² +X² ) such that if it dynamic load is changing with complex impedance or with external excitation Vac injected, then result ,

V= Icc*|Z(f)| must be less than Vcv setting to stay in CC mode.