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Kinetis MKM34Z256VLX7: Vref trim values

Question asked by Matteo Perego on May 4, 2018
Latest reply on May 9, 2018 by xiangjun.rong

Hi,
I am using development board TWR-KM34Z75M and trying to trim the vref values (VREF_H and VREF_L).
On page 654 of the reference manual there's the description of the VREF Trim Register (VREF_VREFH_TRM), and the manual says it is possible to trim the vref value with 0.5mV step.
The minimum value is supposed to be 000000 and the maximum 111111 (x3F), so this means 64 steps of regulation and a total range of 32mV.
Tha manual says to refer to the data sheet for min and max voltage reference values, and on page 32 of the data sheet the possible values of VREFH are:
min. = 1.178V
max. = 1.202V
this means a range = (max - min) = 24mV with 48 steps of regulation (based on the 0.5mV step).
How is it possible?

Can you please explain this mismatch?

 

Best regards

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