Reverse Current for LICELL

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Reverse Current for LICELL

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ko-hey
Senior Contributor II

Hi all

I have a concern about reverse current for LICELL.

I'm planning to use PF3000.

When power supply from the battery is unnecessary (VIN> LICELL).

Could you tell me the reverse current from the PMIC side to the battery side ?

I could not read how we switch between VIN and LICELL internally, but we believe reverse current should flow.

Ko-hey

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frank_zhang
NXP Employee
NXP Employee

Hi ho-key,

    I get some update from PMIC SE.

When VIN> LICELL, VSNVS is powered by VIN.

[Frank] Based on the Table 67 in below figure, it seems that VSNVS is powered by VIN when VIN > VTH1, not VIN>LICELL.

pastedImage_3.png

In this case, we guess some reverse current will occur from PMIC to battery.

   [Frank]

               When the VSNVS is powered by VIN, there is no connection between Coin Cell and VSNVS.

                If we don’t enable the LICELL Charger, there is no current to battery.

               If we enable the LICELL Charger, Coin Cell will be charged by VIN via LICELL Charger, and still disconnect to the VSNVS at this time.

               When VIN<VTL1, VSNVS will switch to Coin cell for power supply.

    Thank you!

Best Regards,

Frank

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art
NXP TechSupport
NXP TechSupport

Hi ko-hey ,

The Frank's explanation above is correct. Do you need any more explanation?


Have a great day,
Artur

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ko-hey
Senior Contributor II

Hi Artur Petukhov

Sorry for late reply.

I'll talk with my customer so please wait a moment.

Ko-hey

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ko-hey
Senior Contributor II

Hi Artur Petukhov

Let us confirm one more thing.

As you said, there is no leakage current generated by the internal parasitic diode.

Am I correct ?

We are assuming whether or not it will flow in nA, pA order, not whether it flows in mA order

In the backup circuit, it was reconfirmed because I could not have the image that there is no leakage current.

Ko-hey

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art
NXP TechSupport
NXP TechSupport

As told before, there is no leakage current from the PMIC side to the coincell. Only the charge current is flowing.

Artur

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frank_zhang
NXP Employee
NXP Employee

Hi Ko-hey,

     Did you mention the Coin chell charge current?  

pastedImage_1.png

     And there are a limit for the maximum load current from coin cell to VSNVS(1000uA)pastedImage_2.png

     Also you can refer to this chapter for the switch logic. Thank you!

pastedImage_3.png

Best Regards,

Frank

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ko-hey
Senior Contributor II

Hi Frank Zhang

Thank you for reply.

No, I didn't.

I mean as below.

When VIN> LICELL, VSNVS is powered by VIN.

In this case, we guess some reverse current will occur from PMIC to battery.

Is there any data for it ?

Ko-hey

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frank_zhang
NXP Employee
NXP Employee

Hi ho-key,

    I get some update from PMIC SE.

When VIN> LICELL, VSNVS is powered by VIN.

[Frank] Based on the Table 67 in below figure, it seems that VSNVS is powered by VIN when VIN > VTH1, not VIN>LICELL.

pastedImage_3.png

In this case, we guess some reverse current will occur from PMIC to battery.

   [Frank]

               When the VSNVS is powered by VIN, there is no connection between Coin Cell and VSNVS.

                If we don’t enable the LICELL Charger, there is no current to battery.

               If we enable the LICELL Charger, Coin Cell will be charged by VIN via LICELL Charger, and still disconnect to the VSNVS at this time.

               When VIN<VTL1, VSNVS will switch to Coin cell for power supply.

    Thank you!

Best Regards,

Frank

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frank_zhang
NXP Employee
NXP Employee

Hi ho-key,

    I can't find the reverse current path based on figure 14 above. I will confrim with pfuse SE tomorrow and let you know.Thank you.

Best Regards,

Frank

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