i.MX28 VDD4P2 Regulated Output and Absolute Maximum Rating

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i.MX28 VDD4P2 Regulated Output and Absolute Maximum Rating

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george
Senior Contributor I

Dear all,

We doubt about the description of the following data sheets.

Somebody should tell the correct interpretation.

  • The absolute maximum rationg of VDD4P2

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  • The VDD4P2 output voltage accuracy

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Aren't two parameters described above contradictory?

Best Regards,

George

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Yuri
NXP TechSupport
NXP TechSupport

Really : Maximum DCDC_BATT / BATT / VDD4p2  value is 4.242 V, even including accuracy of 3 % for VDD4p2.


~Yuri.

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Yuri
NXP TechSupport
NXP TechSupport

Maximum DCDC_BATT / BATT value is 4.242 V, including accuracy (of 3 %),
mainly – in order to avoid  maximum charging voltage for  the Li-Ion batteries.

Have a great day,
Yuri

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Aemj
Contributor IV

Dear Yuri,

Sorry, please let me know a little in more detail.

How meaning are "VDD4P2V" described in the symbol of Table 6 ?

Does it differ from the VDD4P2 internal regulator output?

Best Regards,

George

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Yuri
NXP TechSupport
NXP TechSupport

  The "VDD4P2V" - described in the symbol of Table 6 - yes, it is VDD4P2 regulator

output, which may be used as input of the internal DCDC converter. In this sense it
should be "close" to DCDC_BAT.

Regards,

Yuri.

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george
Senior Contributor I

Dear Yuri,

Thank you for the comment.

I have understood the above your comment somehow.

Please let me know a little in more detail only about "Maximum DCDC_BATT / BATT value is 4.242 V, including accuracy (of 3 %)".

The 4.242V seem to be +1%.


BR,

George

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Yuri
NXP TechSupport
NXP TechSupport

Really : Maximum DCDC_BATT / BATT / VDD4p2  value is 4.242 V, even including accuracy of 3 % for VDD4p2.


~Yuri.

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michaelkoelbl
Contributor III

Hello Yuri,

we have an external charger (TI bq24250) which has a SYS-output where it provides a regulated output in case 5V are present. This SYS-output we want to connect do the DCDC_BATT and BATT pins of the iMX28. This voltage is litte greater than the mentioned max value of 4.242V, it can be as much as 4.37V. Is this allowed?

For the sake of completeness: the charger switches the battery voltage to SYS-output as soon as the 5V are gone.

Thanks,

Michael

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Yuri
NXP TechSupport
NXP TechSupport

Hello,

I am afraid the maximum  value for both DCDC_BATT and BATT is 4.242 V.

This is stated separately for battery charging pin BATT  and for DCDC input

voltage pin (DCDC_BATT) in the Table 6 (DC Absolute Maximum Ratings).
Maximum charging voltage for  the Li-Ion relates to the BATT pin only.

Regards,

Yuri.

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