How to reduce the backup battery power consumption

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How to reduce the backup battery power consumption

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Contributor I

Hi,

     Platform: iMX51

     PMIC: MC13892

     Recently the power consumption when powered by backup battery is too high, the current is about 1mA. Even I disable the VSRTC power supply, the current is still about 100uA. But the current I measure in iMX51 demo board is about 20uA. So I need to ask what internal modules in MC13892 are still powered by backup battery when the main power is dropped? As I know the MC13892 RTC, the core circuit and the backup memory are powered, any other modules? If no more modules how can I reduce the power consumption of these modules. Thank you.

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NXP Employee
NXP Employee

It needs to do test to confirm this issue. We have verified that our EVK board has no such issue, so customer should do comparison based on our hardware design. I have no other comment on this issue.

Regards, Linda

Linda Lin

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NXP Employee
NXP Employee

In RTC mode, MC13892's power consumption is around uA, as it is just 32K works.  Is your hardware design different with our reference design? Please compare the HW design and software.

Linda Lin
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Contributor I

Thank you for your reply, I disabled the 32K output already, also disabled the SRTC power supply (by resetting DRM bit). Now I even disable MC13892 RTC by setting RTCDIS bit, the current is still high.

Can you help me to check which regulators or other modules can consume the power from backup battery?

My board is designed following the ref board. I am trying to compare the differences, can you give me some specific tips? Thanks again.

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NXP Employee
NXP Employee

Is there current leakage?

Regards, Linda

Linda Lin
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Contributor I

I also doubt this, but it is hard to measure which part got leakage. So I want to confirm I've disable all the modules powered by backup battery first.

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NXP Employee
NXP Employee

You should make sure there is no power leakage on your board firstly.

Regards, Linda

Linda Lin
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Contributor I

I've confirmed no power leakage in my board theoretically by analyzing the HW design. The second step I need to confirm all the modules are disabled. If still get high current it must be some physical reasons.

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NXP Employee
NXP Employee

It needs to do test to confirm this issue. We have verified that our EVK board has no such issue, so customer should do comparison based on our hardware design. I have no other comment on this issue.

Regards, Linda

Linda Lin

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Contributor I

Thanks.

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