PF8100 starts only with hardwire configuration

[Tobi_Edu]

Hello everyone,

I have a PF8100CFES, integrated on a custom board with i.MX8 DualX.

The problem is that first, the PMIC didn't start at all, after pulling VDDOTP to V1P5D it starts in default hardwire mode. But the output voltage of SW5 in default hardwire mode is set to 1.1V and I need 1.35V.

The schematic is attached, PWRON is pulled to 1/3*VIN = 1.67V and present. PMIC_INT_N is pulled up with a 100k resistor on another schematic page.

The input voltage VDD5 is resent with about 5.1V, VCCD_1V5 is present with about 1.6V and STANDBY signal is definetly low.

The PMIC does not start up at all with TBBEN pulled up.

How can I get the PMIC start in normal mode with OTP configuration? What else could I try?

The OTP-fuses should be pre-programmed, shouldn't they?

Thank you in advance.

[Tobi_Edu]

Hello David,

thanks for your reply.

Unfortunately, I have already tried all of your recommendations. VDDOTP is pulled to GND with 100k (R28 in schematic, R21 is DNP). VDDIO is bypassed with 220 nF, LICELL is connect to the coin cell battery with 220 nF. I also already tried to connect PWRON directly to VIN (5V) and TBBEN is grounded with a 100k resistor.

Anyway, the PMIC doesn't start with this configuration.

Best regards,

Tobi

[Tobi_Edu]

Hello David,

today I achieved to read out the I2C registers of the PF8100. The switch voltages are loaded correctly from the OTP-fuses and there are no hard fault flags set. Also, OTP_NOK and TRIM_NOK are not set. Anyway, the PMIC does not run. The voltages of all switches, except SW7, are 0V; SW7 equals about 1.7V.

[diazmarin09]

Hello Tobi, 

Thank you for using the NXP communities.

Your configurations seems correct. I am glad to know that the device is addressable. In this case, could you please share the complete schematic? I would like to review the rest of the pins configuration. Besides, could you please share the complete part number? 

Regards,

David

[Tobi_Edu]

Hello David,

thanks for your reply. You find the PMIC-related schematic attached.

The part number of the PMIC is MC33PF8100CFES.

Regards,

Tobi

[Tobi_Edu]

Hello David,

I found out, what the problem was: I connected XFAILB to Ground although it should be pulled up with 100k to V1P5A. Now it works. Thanks for your help.

Regards,

Tobi

[diazmarin09]

Hello Tobi,

I am pleased to know that your device is working as expected. Please let us know if you have any request in the future.

Have a great day. 

Regards,

David

[diazmarin09]

Hello Tobi, 

You are correct, the device is already programmed with the CF configuration.

In this case, please review the recommendations below:

1. Could you please  configure the VDDOTP pin to GND (with a 100 kΩ pull down to ground)? In this case, the device will load the configuration from the OTP mirror registers.
2. I do recommend to keep the TBBEN pin grounded.
3. Bypass VDDIO with a 0.1 µF capacitor.
4. Connect the LICELL pin to coin cell battery with 22 nF capacitor.
5. Connect the PWRON to 100 kΩ pull up to VIN or VSNVS.

Regards,

David