Current monitor/sensor

[Bear1]

Hi guys, I want to build a current monitor/sensor like the voltage monitor, and I can set the current limit I want.  Can anyone help me and give me a diagram.  Thanks.

 

[audioguru2]

You didn't say if the current is AC or DC, and you didn't say how much current or voltage.

 

[waferstar]

I think if need a simple ,you can use the Variable-Resistance(VR),and set the current to your need and then use a Comparator .
Or use a small value Resistance to sample the current ,and then get the volatage to analysis.
that is the similar in the battery charger.


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[Bear1]

the value I am looking about 3Amp DC.
Do you guys have schematic diagram for the current sensor

 

[denci]

Hi guys!

I want to sensing the current in my circuit (SLA battery tester) with current monitor IC ZXCT1109 but i have one question/issue?
Can i sense the current with Rload before the ZXCT or i need to use Rload as shown in datasheet?
Below is picture to best undertending:

In my case:
attach

View attachment 41774

 

[denci]

I tried to sense current with this methode but i can't read any voltage on output pin, which connect to the ADC pin of microconroller...
I don't know if problem has occured in circuit or anything else?

 

[audioguru2]

I want to sense the current in my circuit (SLA battery tester) with current monitor IC ZXCT1109 but i have one question/issue:
Can i sense the current with Rload before the ZXCT or i need to use Rload as shown in datasheet?

I tried to sense current with this methode but i can't read any voltage on output pin

The IC is called and is shown as a high side current sensor but you connected it as a low side current sensor so of course it WILL NOT WORK!View attachment 41775

 

[denci]

Tnx,

so can I replace the existing chip (current monitor) with other, which have a low side current sensing?
Is there any ZXCT series alternative??

 

[denci]

What will happen, if i put another 10mE resistor as load, and than sensing the current.
It will work or not?
This may be the best solution for me, because otherwise i must change the way of current sensing

 

[denci]

can anyone hlep me because im not really shure that i will solve this problem on that way

 

[audioguru2]

I don't know if anybody makes a Low Side current sensor. It would be easy to make one.

 

[denci]

I don't know if anybody makes a Low Side current sensor. It would be easy to make one.

What will happen, if i put another 10mE resistor as load, as i wrote above??
Will this work or not, i think that it should be work??

 

[audioguru2]

What will happen, if i put another 10mE resistor as load, as i wrote above??
Will this work or not, i think that it should be work??

Use Ohm's Law and simple arithmatic to calculate how many thousands of Amps will try to flow.

 

[denci]

It is true but i have one resitor 0,47E before ZXCT current monitor, which is regulated by OPAMP pwm controled and limiting current is about 10Amps.
Therefore can I use onther 10mE resistor as load and sensing the current on this resistor, so i don't need to change my circuit, just put in the line??
I hope that it is understandable!

 

[audioguru2]

I do not know why you are doing things completely differently to the circuits in the datasheet of the IC.

 

[denci]

I made a battery analyzer, which can analyze the battery and discharge it. I can set up the discharge current with pwm controled voltage regulated through resistor. Voltage on resistor limitc the current, which flow from battery. I did the mistake and i put ZXCT at the end of circuit, because i was not careful what is show in datasheet. This analyzer would also be possibility of charge the baterry and all circuit swithing between charge and discharge through two relay and therefore i put the current monitor at the and of circuit but i made a mistake as shown.

How can I avoid this problem?

 

[denci]

Any idea??

 

[denci]

OK, I fixed the problem and i put the ZXCT1109 as shown in datasheet but i still have one problem.
If i want to get 0-5V output voltage and 0-10A sensing current i must put the Rsense of volue 10mE and Rgain 12,5kE, i get equations in datasheet.
But now i testnig the proper function of this measurments and i get 140mV in output with sense voltage 8,5mV and 410mV with sense voltage 16,4mV.
This is not what i want and not as calculated, it must be something wrong because i should get 0,5V in output with 1A (10mV sense voltage) current and so on, therefore 2A/V resolution??
???

 

[denci]

Any idea?