PMIC(MMPF0100F4AEP) MCURESET & POR_B

[kwangbogham]

Dear Sir,

Thank you for response about my question which i posted.

We had designed our board with MMPF0100F4AEP & i.mx6 solo lite.

As soon as our board have been assemblied,

i checked the voltage as the below procedure:

[Common]

- input VIN, VIN1, VIN2 and VIN3 on PMIC is 3.3V

[Step]

Step1: 32.768KHz and 24MHz is proper working.

Step2: VSNSVS voltage on PMIC. it's 3.0V. (OK)

Step3: PMIC_ON_REQ signal voltage from MCU. it's 3.0V (OK)

Step4: PMIC's LDO output voltage, DCDC step down output voltage and DCDC step up output voltage on PMIC.

           Everything are OK. (it means that the meausrement voltages are equal to them in the MMPF0100F4AEP's datasheet)

Step5: Here's problem.

           /RESETMCU voltate on PMIC. it's 0.7V.(Problem)

           Please, refer to the attached our schematic.

[Question-1]

The attached file schematic is the same as the schametic of freescale's EK board for i.mx6 solo lite.

But, /RESETMCU pin voltate is 0.7V.

Could you recommand to me that which one is wrong?

Or, do i should check and consider which part?

Best & Regards,

Kwangbog HAM

[igorpadykov]

Hi kwangbog

just for test one can pull-up RESETMCU with 1Kohm resistor

and test if it has short circuit with some other lines (disconnect

it from processor). Also RESETMCU may stay low in fault mode

(bit OTP_PG_EN=1), this is described in sect.5.3.2.1 Interface Signals

MMPF0100

Best regards

igor

[kwangbogham]

Dear igor,

Thank you for your fast response.

As you mentioned, i tried something like the below:

[Step 1]

Originally,  /RESETMCU pin on PMIC is connected to POR_B pin on MCU through one resistor 0 ohm (this connection is the same with your EK board schematic)

Just for test, i attached pull-up resistor 10Kohm through 3.3V.

Finally, i checked the volate of PMIC_ON_REQ signal.

It's voltage 0.7V.

[Step 2 - In order to know whether PMIC is work well or not ]

Just for test and in order to find out the place which one(MCU or PMIC) is falut,

i detached the resistor 0 ohm and attached the pull up resistor 10Kohm at /RESETMCU pin on PMIC through 3.3V.

Finally, i checked the voltage of /RESETMCU pin on PMIC.

It's 3.3V.

Maybe i think that PMIC is working properly. is it right?

[Step3- In order to know whether PORB pin on MCU is work well or not]

Just for test and in order to find out the place which one(MCU or PMIC) is falut,

i detached the resistor 0 ohm and attached direct 3.3V at PORB pin on PMIC without pull-up resistor.

Finally, i checked the voltageof PORB pin on MCU.

It's 3.3V.

Maybe i think that PMIC is working properly. is it right?

[Step4- In order to know whether PORB pin on MCU is work well or not]

Just for test and in order to find out the place which one(MCU or PMIC) is falut,

i detached the resistor 0 ohm and attached the pull up resistor 10Kohm at PORB pin on PMIC through 3.3V.

Finally, i checked the voltageof PORB pin on MCU.

It's 0.7V.

Based on my step2 test, maybe i can think that PMIC is work well.

But, based on the step1, step4, POR_B pin on the MCU has pull down resistor, instead of pull up resitor in default. right?

Plz, check my steps and give me your advice to find out which one is problem.

Best & Regards,

Kwangbog HAM

[kwangbogham]

Dear igor,

PMIC is MMPF0100F4AEP.

Which one is right? fault mode or default mode.

Kwangbog HAM

[igorpadykov]

Hi kwangbog

is this one board issue, if yes

than one can try to replace processor.

Also one can check layout with x-ray screeneg

for short circuits.

~igor

[kwangbogham]

Dear sir,

My think is that this problem is not MCU part but PMIC part.

I did the additional testing for checking the voltage level of /RESETMCU pin.

Plz, give a check point to me to find out which one is problem.

[Test method]

I detached the 0 ohm resistor between the  /RESETMCU pin on PMIC and POR_B pin on MCU.

And then, i attached the pull-down resitor 10Kohm to  /RESETMCU pin on PMIC in order to check the exact voltage level.

[Result]

Voltage level is 0V and  other signals(LDOs, DCDC step-up, step down output) are working well.

I think that this result means that PMIC is in the fault . This signal is not short with other signals.

And now,

I think that the errata number ER22 in the MMPF0100 errata (Document Number: MMPF0100ER) is not clear,

even if you indicated "Fixed on PF0100A" in this document.

[Further testing]

I will replace this chip (MMPF0100F4AEP) to MMPF0100F0ANES and then, try it again.

Best & Regards,

Kwangbog HAM.

[igorpadykov]

Hi

your test is not correct:

attach pull-up (SNVS) resitor 10Kohm to  /RESETMCU pin on PMIC

and check.

Then based on that result please make decision about pmic change.

~igor

[kwangbogham]

Dear Igor,

Thank you for your response.

[Step]

Originally,  /RESETMCU pin on PMIC is connected to POR_B pin on MCU through one resistor 0 ohm (this connection is the same with your EK board schematic)

Just for test as you metioned, i attached pull-up resistor 10Kohm through VSNVS as the attched schematic.

[Result]

I checked the volate of PMIC_ON_REQ signal.

It's voltage 0.7V.

[Further more testing next week]

I will replace this chip (MMPF0100F4AEP) to MMPF0100F0ANES and then, try it again.

[Request]

If the MMPF0100F0ANES testing result is the same with before, do you have any solution to find out which one probem?

I can give you our schematic, artwork file and PCB gerber file.

Plz, give the exact guideline or solution to me.

Best & Regards,

Kwangbog HAM

[igorpadykov]

Hi Kwangbog

I do not understand you:

original problem was with PMIC RESETMCU (connected to i.MX6 POR)

and actually I suggested to check layout for possible short circuit and

replace processor not pmic.

Now you are asking about other signal PMIC_ON_REQ.

You can try to attach pull-up resistor 10Kohm to any available 3.3V power

just for test (not SNVS).

~igor

[kwangbogham]

Dear Igor,

Sorry, the schematic which i posted this morning was my mistake.

Plz, refer to the correct picture as the below:

(PF100_VIN is 3.3V)

I think that MCU is working well

because VDD_ARM_CAP, VDD_SOC_CAP, VDD_PU_CAP, VDD_SNVS_CAP, VDD_HIGH_CAP, VDD_HIGH_CAP are working well.

(These signal's output voltage are the same as the datasheet)

Before i replace the present MCU to other MCU as you mentioned, i have one question.

Why do you think that the problem is MCU part or short circuit of MCU part?

The reason which i think that PMIC is problem is the below:

1. LDO working well, DC/DC working well, but only RESETMCU pin is not working.

2. This pin is not short

[igorpadykov]

Hi Kwangbog

since RESETMCU pin is not working

I suggest that this pin is shorted somewhere.

~igor