PMIC for i.MX 8M Mini Family - BD71847MWV

[shai_b]

Hello Team,

My customer is using Rohm BD71847MWV PMIC (as was recommended in the old iMX8 M mini EVK).

right now they have done the first PCB, but when they powered the PCB the PMIC only provide 1.8V and not able to power-up the iMX8.

according to what I know the customer should init/config the PIMC before he can work with the iMX8.

Could you please advise how the best approach to solve this issue?, (if he needs to config the PMIC using external i2c-USB or there is any way to make the iMX8 init/config the PMIC even at the first stage the PMIC provide only 1.8V)

Waiting for your kind response, Thaks in advance 

Shai

[igorpadykov]

Hi Shai

in general pmic voltages can be changed (reprogrammed) after processor boot, before boot

pmic uses default voltage settings. If they are wrong probably board has wrong pmic connections,

one can recheck and compare them with EVK schematic on

i.MX 8M Mini Evaluation Kit DDR4 Design Files

and using sect.3.6.1. i.MX 8M Mini power distribution block diagram

i.MX 8M Mini Hardware Developer’s Guide

Best regards
igor

[shai_b]

Hello Igor,

My customer IMX8mini design includes 2 cards:

Card 1: Main Power with BD71847MWV part.
Card 2: IM8 Mini + Memory

when they are measuring the NVCC_SNVS_1V8 and the VDD_SNVS_0V8 without the imx8 main card, the voltage, CLK_32K_OUT, and INTLDO_1V5 are ok
When they are connecting the IMX8 Card to the Main power Card (by Board to Board connector), The voltages NVCC_SNVS_1V8 and the VDD_SNVS_0V8, CLK_32K_OUTand INTLDO_1V5 are 0V.
Any idea of what they may miss?
The Boot mode connect as below:

Could you please advise back, Thanks in advance?

Kind regards,

Shai

[igorpadykov]

Hi Shai

> IMX8mini design includes 2 cards:
>Card 1: Main Power with BD71847MWV part.
>Card 2: IM8 Mini + Memory
>..when they are measuring the NVCC_SNVS_1V8 and the VDD_SNVS_0V8
>without the imx8 main card..

such operation - without the imx8 main card, that is without BD71847MWV PMIC -
is not allowed as it violates power up sequence described in sect.3.2.1 Power-up sequence

i.MX 8M Mini Applications Processor Datasheet for Consumer Products

Best regards
igor

[igorpadykov]

Hi Shai

> IMX8mini design includes 2 cards:
>Card 1: Main Power with BD71847MWV part.
>Card 2: IM8 Mini + Memory
>..when they are measuring the NVCC_SNVS_1V8 and the VDD_SNVS_0V8
>without the imx8 main card..

such operation - without the imx8 main card, that is without BD71847MWV PMIC -
is not allowed as it violates power up sequence described in sect.3.2.1 Power-up sequence

i.MX 8M Mini Applications Processor Datasheet for Consumer Products

Best regards
igor

[shai_b]

Hi @igorpadykov Igor,

The customer found that he had a short on the PCB at the DRAM side, Could you please confirm that without passing the LPDDR4 stage (fail on step 6) the PMIC would not power up the other sequence/pins? 

Thanks in advance 

regards,

Shai

[igorpadykov · Accepted solution]

Hi Shai

yes confirmed.

BD71847 has VR (Voltage Regulator) fault detection function which monitors
all relevant VR’s of the system. The system is shut down when a monitored voltage rail
goes out of the target voltage.

Best regards
igor