Verdin IMX8MP does not boot when charging battery

when we use Verdin IMX8MP Q 4GBIT V1.1A, some of our boards don’t boot.

We tracked the problem down to battery charging. First of all, we have

&rtc_i2c {
        aux-voltage-chargeable = <1>;
        status = "okay";

in our BSP. Disabling the aux-voltage-chargeable = <1>; line “resolves” the problem, but we need the charging.

This is our battery circuit:


We did some measurements, also on the verdin module itself. This is a schematic taken from Verdin datasheet:

We measured that in the failed state, CTRL_RESET_MOCI is down, POR_B (pin on PMIC) is down, JTAG_1_TRST (which is floating on carrier board) is down as well. We were also able to verify that the PMIC chip is fully initialized (by reading its STATUS2 register using external I2C adaptor).

When we desoldered our battery, problem disappeared. Also when I leave the device in the failed state for some time, the device boots.

It all points to a conclusion that when the battery is low (below cca 2.6V), RX8130 pulls down its /RST pin and resets the board until battery is charged. However, according to RX8130 datasheet, the /RST pin should only be pulled down when VDD is low, not VBAT.

Is there something wrong with our setup? If not, how can we deal with discharged battery?

EDIT: I forgot to mention that “Verdin IMX8MP Q 4GB WB IT V1.0C” does not behave like this. When we replace the failing 1.1 Verdin by 1.0 Verdin, the 1.0 Verdin boots without any problem.

Yes this is a known issue,

In the V1.1A version, the RTC has a series resistor R136 on its supply. If charging is enabled the current thru the resistor cause a huge voltage drop that disables the clock output. And this clock is needed by the PIMIC therefore the crash.

Right now you could replace your series resistor to a much higher value but this would mean minimal charging current.
So right now I would recommend not using the charging feature of the RTC.
instead, charge it from an external voltage.

OK, thank you. Just one follow-up question: is there a list of known Verdin issues? We are going to design a custom carrier board, and such list would be really beneficial for us.

I know about Errata/Known Issues section, but it does not say anything about this one.

Yes, this issue is very new so it is not yet in the known Issues list.
If you are designing a carrier board please send a request for a carrier design guide video call to
We will give you a best practice guide for your design.

Best Regards,

Matthias Gohlke

1 Like

is the issue going to be solved on the upcoming Verdin IMX8MP V1.1B?
Thank you

Hallo @adam.trhon,

It does not look like that the charging feature will be officially added to the documentation and fixed.
But I check for an official statement.

Best Regards,

Matthias Gohlke