Battery relevant power circuit change

[zzzh]

NO_BATTERY.jpg

Hi, all,

I am working on a board based on i.mx283, since don't need to support lithium battery, it have a change in battery relevant circuit, as the attachment show.

The problem is, on this board , the VDD4P2 is measured as 1.1V, not supposed 4.2V, and the CPU can't work properly, my question is, is it because that change lead to this wrong voltage of VDD4P2? if it is, why?

Any help appreciated, thanks.

Zhu

[zzzh]

And, I checked a dev-board, when booing up from usb mode(no power up code to run), the VDD4P2 is measured to be 2.0V, not 1.1V.

Is this 1.1V because of the circuit change?

[fluiss]

Hi Zhu,

Did you finally solve the problem? I have a similar trouble when I'm powering the board. Values from linear regs are wrong and VDD4P2 is about 0,7V. The thing is that this happens whe powering, I have not even the opportunity to upload the firmware.

Thx!

[zzzh]

Hello Chuck,

Thanks for your reply and the AN4199, I read it around the 4.2V issue.

I checked 5V power connected, and it's always be around 5.1V.

Since this board have not been programed, there is no power up code to run.

I realized that at power on time, the 4.2V regulator is not enabled.

The problem is, when trying mfgtools, it would have 1167 error. what power situation would make this error happen?

Thanks & Regards,

Zhu

[ChuckFarago]

Hello Zhu,

Do you have the 5V USB/charger connected, and is it always > 4.4V?  Please see attached application note.

Thanks & Regards,

Chuck

Freescale PMIC Applications