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Current measure is noisy

Question asked by Jean Viaene on Jul 8, 2019
Latest reply on Jul 10, 2019 by Wolfgang Bihlmayr

Dear support / community,

 

I have tested the MM9Z_638 over a wide range of current, and after quite some debugging, it turned out that some noise on ISENSE is created by switching back and forth the TSENSE from internal temp to external temp (PTB3).

 

Curiously, I see a pick of error at a given current, depending on the PGA threshold configured for the current. With a certain configuration (3/16 and 13/16) we had a strong pick of error (>10A)  at 158A, which also increases with the temperature. 5A above or below, the error tends to disappear. Now with a different window of (14/16 and 2/16), the error is way smaller, but still noticeable, and now at about 440 A.

 

Is there a way to switch back and forth between internal temperature and external temperature (or voltage) without causing noise on the current measure ?

 

Kind regards,

Jean

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