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Hello Every one,
I took one example code for PGA. I set 1 V from VDAC and measuring the output. The problem is, if i set gain of 8 or higher it is only showing me 3.284 V on Multimeter.
Can you tell me why this is happening and how i can get rid of this thing?
Looking forward for your suggestions.
Regards
Awais
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I am using PSOC 5LP.
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The input and output V limits of a psoc pin and analog
are basically Vdda >= Vanalog >= 0. So with a G = 8, and
input of 1 V, you are asking for 8V out, which exceeds your
Vdda.
Regards, Dana.
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Sorry,
I didnt get your point.
How i can set my Vdda Value in order to get accurate result?
Regards
Awais
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The CM range is limited by -
Vdda >= Vanalog >= 0 and Vdda is basically limited to 3.3 V or 5V, see spec sheet
for exact number.
You cannot get > Vdda out of the chip.
Regards, Dana.
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oh yes,
Now i know what do u mean 🙂
Thankyou for your replay.
Regards
Awais
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Glad I could help.
Regards, Dana.
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Hi One more time 🙂
So this means it applies to normal op amps also?
I cannot get more than 5 volts?
Am i right?
Regards
Awais
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Thats correct.
If you need to get higher voltage swings you can use external parts, split power
supplies to do that.
Regards, Dana.
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If you need to produce higher V swings that a PSOC Vdda allows you
can use external OpAmp running on higher voltages, and / or split supplies.
Some ways of generating simple negative supplies for a split supply application
here -
www.dropbox.com/s/k1yn4m7heaixvmg/ADinput%20negative%20inputs.zip
Note you can, in some applications, use an unregulated supply on external OpAmp
because its PSRR aids in reducing its supply sensitivity to changes in its supply.
Regards, Dana.