ADC12 differential pair & single ended mixed

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ADC12 differential pair & single ended mixed

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matthiasuhlmann
Contributor II

Hi all,

 

I set up ADC12 to measure:

- ANA0 & ANA1 as differential pair

- ANA3 as single ended

- ANB0 & ANB1 as differential pair

- ANB3 as single ended

- ANB4 as single ended

 

i use A & B channel in triggered parallel mode and run them independent.

 

Problem:

sample ANB3 & ANB4 deliver complete wrong result:

=> if ADC voltage increase, ADC result decrease

 

Is it possible that there is a Problem on ADC12?

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395 Views
xiangjun_rong
NXP TechSupport
NXP TechSupport

Hi,

 have you set the SIMULT in ADCx_CTRL2 register?

BR

XiangJun Rong

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395 Views
matthiasuhlmann
Contributor II

Hi Xiang.Jun Rong,

No we do parallel scans independently.

BR

Matthias

Matthias Uhlmann

Engineer Software Design

Bel Power Solutions & Protection

O +41 44 944 8103

E matthias.uhlmann@psbel.com<mailto:matthias.uhlmann@psbel.com>

Ackerstrasse 56, 8610 Uster, Switzerland

belpowersolutions.com<http://belpowersolutions.com/>

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395 Views
xiangjun_rong
NXP TechSupport
NXP TechSupport

Hi,

Pls set the SIMULT bit and have a try. from my experience, there is incorrect sample if you clear SIMULT bit.

BR

Xiangjun Rong

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395 Views
matthiasuhlmann
Contributor II

But is it no problem if we need to trigger both ADC channels (A & B) independent? It is really important that first sample of both channels are placed accurate based on its sample trigger.

BR

Matthias Uhlmann

Engineer Software Design

Bel Power Solutions & Protection

O +41 44 944 8103

E matthias.uhlmann@psbel.com<mailto:matthias.uhlmann@psbel.com>

Ackerstrasse 56, 8610 Uster, Switzerland

belpowersolutions.com<http://belpowersolutions.com/>

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395 Views
xiangjun_rong
NXP TechSupport
NXP TechSupport

 Hi,

I suggest you set the SIMULT bit and have a try. From my experience, there is incorrect sample if you clear SIMULT bit sometimes.

BR

Xiangjun Rong

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395 Views
matthiasuhlmann
Contributor II

Hi Xiangjun Rong,

if SIMULT bit is set, differential samlaple is ok, but this will not work for our Need!

 We Need to trigger bot ADC Chanels Independent and Chanel B EOC Interrupt will execut Regulation Loop.

It is critical that sample is taken at a defined time to get needed result!

Is there no way to use differential samples if we Need tu run Chanel A & B independently?

Is this a bug within the ADC Modul? Why is there no errata for this behavior?

BR

Matthias

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395 Views
xiangjun_rong
NXP TechSupport
NXP TechSupport

Hi, Matthias,

From my experience, if you use different trigger to trigger ADCA and ADCB independently, there is abnormal sample result for only ADCB module  randomly, but the phenomenon is not documented in errata.

Hope it can help you.

BR

Xiangjun Rong

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