S32K344 Custom Board Reset Problem

[mesutkilicmak]

I have designed custom board with S32K344 and FS26 PMIC chip. I have used S32K3X4EVB-T172 EVAL Board as a reference.In my custom board reset pin always 160 mV. I could not managed to connect chip with J-link or I-jet. Where should I be looking for the problem? Can someone help me?

PMIC output voltages:

1V1 =1.13V

1V5 = 1.37V 

2V5 = 2.57V

5V = 4.98V

3V3 = 3.30V

[danielmartynek]

Hi @mesutkilicmak,

Is the HSE_FW installed on the MCU?

Can you disconnect the reset_b from other devices on the board?

Can you measure the reset_b pin with an oscilloscope?

Is it permanently at 160mV or is it toggling?

If it is toggling, it could be becasue of the V15 voltage which is too low 1.37V.

Regards,

Daniel

[mesutkilicmak]

Hi @danielmartynek 

No firmware installed on MCU, because of I could not connect. Newly soldered.

I can not disconnect reset_b pin, because the pin directly connected to FS26 chip RSTB pin.

I measured reset_b pin with an oscilloscope. It is always 160 mV and stable.

[danielmartynek]

Do you have more of those boards with this issue?

Can you meansure the power supply directly at the pads of the MCU?

Thanks,

Daniel

[mesutkilicmak]

Hi @danielmartynek,

It is the first board for this project. I have only one board available. 

I measured SBC output voltages. All voltages stable except 1V5. This output has sawtooth like shape.

I have MFS2613AMDA4AD chip on the circuit and 1V5 circuit is shown down below. 

Is there a problem with this circuit? 

Thanks,

Mesut

[danielmartynek]

Hi Mesut,

Can you share the whole schematic?

If you don't want to post it here, you can create a ticket.

Regards,

Daniel

[danielmartynek]

Hi @mesutkilicmak,

Thank you for creating the ticket and sending the schematic.

Can you check if the MCU or the SBC is heating?

There is a possibility that the 1V5 source is 1.37V because either of the chips have been shorted and burnt.

Best regards,

Daniel

[JozefKozon]

Hi Mesut,

do you use the FS26 SBC in Normal Mode or in Debug Mode. In Normal Mode the FS26 requires periodical watchdog refresh. For MCU software debugging or first MCU programming, it is recommended to set the FS26 to Debug Mode. It is done by applying voltage from 2.5V to 6.0V at the Debug pin of the FS26 before the power supply is applied. In the Debug Mode, no watchdog refresh is required.

With Best Regards,

Jozef