IMX7ULP VDD_VBAT42 Supply Input

[ibocakir06]

Hi, I am making the hardware design of IMX7ULP nowadays. I have a question about VDD_VBAT42 input.

The datasheet says that "VDD_VBAT42 must be powered and stable before all other supplies begin to ramp up."

When I check the reference SoM schematic of IMX7ULP, SPF-29163, the VDD_VBAT42 input of SoC is supplied from VSYS with a schottky diode. Why is it done this way? See figure below.

However, the VSNVS output of the PMIC 1550 is not used, just decoupled with 1uF, which is 3V0 acceptable.

I don't want to use an extra diode and want to supply the VDD_VBAT42 pin with VSNVS. Is there any problem?

#imx7ulp

Thanks.

[ibocakir06]

Hi, thanks for the quick response.

I understand the diode usage. If you supply the VDD_VBAT42 pin from VSYS_4.2V you must use the diode.

However, I want to supply the VDD_VBAT42 pin from the VSNVS output of the PMIC PF1550. Which is always-on, fixed 3.0V, sequence 0. Is it possible? 

The PMIC can supply maximum of 2mA from VSNVS output. IMX7 datasheet says that the max drawn current from VDD_VBAT42 is 0.023mA.

Thanks.

[igorpadykov · Accepted solution]

>I want to supply the VDD_VBAT42 pin from the VSNVS output of the PMIC PF1550.

>Which is always-on, fixed 3.0V, sequence 0. Is it possible? 

yes this is possible.

Best regards
igor

[igorpadykov]

Hi İbrahim

schottky diode is needed for providing some margin for VDD_VBAT42, since SYS_4V2 is 4.2V

and VDD_VBAT42 has max. voltage also 4.2V.

Best regards
igor

[ibocakir06]

Hi, thanks for the quick response.

I understand the diode usage. If you supply the VDD_VBAT42 pin from VSYS_4.2V you must use the diode.

However, I want to supply the VDD_VBAT42 pin from the VSNVS output of the PMIC PF1550. Which is always-on, fixed 3.0V, sequence 0. Is it possible? 

The PMIC can supply maximum of 2mA from VSNVS output. IMX7 datasheet says that the max drawn current from VDD_VBAT42 is 0.023mA.

Thanks.

(Can you delete my reply upside?)