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i.MX6 ZQ pull-down calibration.

Question asked by Takayuki Ishii on Jan 15, 2018
Latest reply on Jan 16, 2018 by Takayuki Ishii

Hello community,

 

I have a question about method of ZQ automatic pull-down calibration.

 

In ZQ automatic Pull-up calibration(section 44.11.2.1.1), it say that

 "The MMDC drives zq_pu_pd_sel to "1"for indication of pull-up calibration"

 

From Figure 44-8 in Reference manual, It will connect between internal pull-up and external pull-down

register and calibrate a ZQPAD voltage to Vdd/2.

 

In ZQ automatic Pull-down calibration(44.11.2.1.2), it say that

"The MMDC drives zq_pu_pd_sel to "0" for indication of pull-down calibration"

In Figure 44-8, it seems that detach internal pull-up register and attach internal pull-down register

to external register.

 

 

It seems that both internal and external register are pull-down so ZQPAD keep GND level.

 

So we think that in pull-down zq calibration, internal pull-up and internal pull-down register

will attached to the comparator and detach external register.

 

 

Is it correct understanding?

 

Best regards,

Ishii.

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