topic Re: Reverse Current for LICELL in i.MX Processors

Reverse Current for LICELL

ko-hey — Thu, 31 Aug 2017 05:01:55 GMT

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

Re: Reverse Current for LICELL

frank_zhang — Thu, 31 Aug 2017 06:23:27 GMT

Hi Ko-hey,

Did you mention the Coin chell charge current?

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

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

Best Regards,

Frank

Re: Reverse Current for LICELL

ko-hey — Thu, 31 Aug 2017 08:37:47 GMT

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

Re: Reverse Current for LICELL

frank_zhang — Thu, 31 Aug 2017 10:30:52 GMT

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

Re: Reverse Current for LICELL

frank_zhang — Fri, 01 Sep 2017 07:50:34 GMT

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.

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

Re: Reverse Current for LICELL

art — Mon, 04 Sep 2017 11:14:58 GMT

Hi ko-hey ,

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

Have a great day,
Artur

Re: Reverse Current for LICELL

ko-hey — Tue, 05 Sep 2017 01:12:31 GMT

Hi Artur Petukhov

Sorry for late reply.

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

Ko-hey

Re: Reverse Current for LICELL

ko-hey — Wed, 06 Sep 2017 07:17:35 GMT

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

Re: Reverse Current for LICELL

art — Wed, 06 Sep 2017 10:31:45 GMT

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

Artur