i.MX6 DRAM_SDCKEx external resistor.

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i.MX6 DRAM_SDCKEx external resistor.

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satoshishimoda
Senior Contributor I

Hi community,

I have a question about i.MX6SDL, i.MX6DQ DDR design.

Please see No.4 of Table 1-1 in IMX6DQ6SDLHDG "Rev.0".

It says "DRAM_SDCKE0 and DRAM_SDCKE1 should be connected to individual 10 kΩ5% resistors to GND."

On the other hand, No.4 of Table 2-1 in IMX6DQ6SDLHDG "Rev.1", It says "DRAM_SDCKE0 and DRAM_SDCKE1 no longer require external 10 kΩresistors to GND to minimize current drain during deep sleep mode (DSM)."

In fact, I got a following reply in past in SR# 1-1132121434.

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Internal pull down resistor of 100 KOhm provides relatively “weak” pulling down.

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Why the recommended disign was changed?

This weak pull down issue have been fixed?

Best Regards,

Satoshi Shimoda

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Satoshi

please check recommendations in latest HW Design Checklist

HW Design Checking List for i.MX6DQSDL

10k may be needed to improve noise immunity (for example

strong EMI) since internal are weak.

Best regards

igor

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Satoshi

please check recommendations in latest HW Design Checklist

HW Design Checking List for i.MX6DQSDL

10k may be needed to improve noise immunity (for example

strong EMI) since internal are weak.

Best regards

igor

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

-----------------------------------------------------------------------------------------------------------------------

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satoshishimoda
Senior Contributor I

Hi Igor,

Thank you for your reply.

According to your reply, the external resistor is not needed if a product is designed with good EMC, right?

Best Regards,

Satoshi Shimoda

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Satoshi

yes right.

Best regards

igor

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satoshishimoda
Senior Contributor I

Hi Igor,

Thank you for your reply.

OK, I understood.

And I posted a new question about Ref7 (DDR SDCKE) of the design checking list to HW Design Checking List for i.MX6DQSDL.

Would you support it also if you can?

Best Regards,

Satoshi Shimoda

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