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INA193 High side current sensing, ground problem?

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SiliconWizard:

--- Quote from: Atom on August 14, 2019, 10:15:51 pm ---4 where did you rad Vccmin ?
--- End quote ---

I didn't, that's why I asked. ;D
If Vccmin was high enough, then you could use a step-down converter. That was the reason for asking.


--- Quote from: Atom on August 14, 2019, 10:15:51 pm --- i dont want to use a step down converter because i want the INA 193 to always work...for example the load is powered by 1 V ..and the INA193 has its own 5V(VDD) power supply ..by doing so i can measure the current even if VCC is 1V

--- End quote ---

OK that was the answer. VCCmin would not be high enough for the above solution.

Have you tried connecting the - terminal of both PSUs together, not connecting the + terminals to your circuit. And measure voltage between each + terminal and the common - ?
Just to check that they behave properly in this setup.

Atom:

--- Quote from: SiliconWizard on August 14, 2019, 10:24:01 pm ---
Have you tried connecting the - terminal of both PSUs together, not connecting the + terminals to your circuit. And measure voltage between each + terminal and the common - ?
Just to check that they behave properly in this setup.


--- End quote ---

i'll try to do that.

here's the video https://drive.google.com/file/d/1pPiyfZVf9aA8VIY2rUKaO65FmYq3KZjR/view?usp=sharing

namster:
for low  cost regulation you can use a zener diode , by choosing the right value of  R3 , in previous post i connected the rĂ©gulator before the shunt resistor that was error on my part , the INA193 brunout beaucoup of high supply voltage ! not because you connect the ground together .
for more viable version you can replace your adc with another wich have separate ground ( Analog and Digital ) .

Jeroen3:
Good video!

Mistake 1: at 2:58 you connect the second power supply, before it's ground was made common. This creates a surge of current through the INA. However, it doesn't in your case, read below.
Mistake 2: at 7:26 you short the ina output.

Either: the problem seems to be your Delta Electronic power supply is sinking current. Somewhere supplies are not as isolated at you think they are.

Or you board accidentally parallels the power supplies, trough the INA. Does it get hot when you run an amp trough it?
You might have fried internal R1 with mistake 1 causing the INA to lose it's common mode capabilities.

By default the Delta one does not come with banana plug on the front, are the connections on the rear touching something?

Atom:

--- Quote from: Jeroen3 on August 15, 2019, 06:48:20 pm ---Good video!

Mistake 1: at 2:58 you connect the second power supply, before it's ground was made common. This creates a surge of current through the INA. However, it doesn't in your case, read below.
Mistake 2: at 7:26 you short the ina output.

Either: the problem seems to be your Delta Electronic power supply is sinking current. Somewhere supplies are not as isolated at you think they are.

Or you board accidentally parallels the power supplies, trough the INA. Does it get hot when you run an amp trough it?
You might have fried internal R1 with mistake 1 causing the INA to lose it's common mode capabilities.

By default the Delta one does not come with banana plug on the front, are the connections on the rear touching something?

--- End quote ---

thanks, yes at 7.26 i shorted the output of the INA193 |O in fact i kinda pull off the cables really quickly ...the ina didnt get damaged so its all good, i have another 7 so i shoulfìd be able to solve the problem without frying them all.

yep the delta psu is sinking current.

now ive done further testing and there are 2 situations but befor lets clarify some things:

VCC is a voltage variable from 0-70V , this voltage is the voltage applied to the load ...the ina193 has a voltage rating of 80V so it should be fine.
VDD is a voltage bigger than 5V so the 5V lin reg can regulate the voltage(this is the "logic" supply voltage)

SITUATION 1. VCC<5v (why 5v ? because its the supply voltage of the ina)

when connecting the 2 grounds togheter i get huge currents passing trough the "common ground lead"... from 500ma to even 1A, the readings from the ina gets all wrong and the voltage VCC gets pulled up to 5 V

its seems like the voltage regulator (the 5V one is bringging up the VCC rail)

SITUATION 2. VCC>5V

connecting the 2 grounds togheter i can see a current of 5ma flowing at about VCC =12V... bringing up the voltage of VCC brings up also the current in fact at VCC=40V the current measured is 40ma, at this point the INA193 relases the magic smoke and burns.

any help is appreciated |O


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