The case that internal DC-DC didn't output 1.1V in RT1021

[Edgard]

Dear a NXP Engineer,

recently the circuits that I desinged  sometimes didn't work well.
It is true that extarnal Power Supply +3.3V caused the sympton.

Now I'm reserching the reason, I found DC-DC doesn't output 1.1V.
But the external voltage value is correct and it is within the regulation.

If could, I would like to get some hints in order to check the point which causes that trouble.

Thanks in advance.

[Edgard]

Dear Kerry,

just now I checked the Power-up sequence and I found it was no problem.

But I have another question. 
Is it true that Power-up Boot Sequence depends on USB_OTG1_VUBS?

Kindest Regards

Edgard

[kerryzhou]

Hi @Edgard ,

  Please provide your power on wave, especially, the 1ms DCDC_PSWTICH and DCDC_in.

  It is determined by the VDD_SNVS_IN, VDD_HIGH_IN, DCDC_IN, DCDC_PSWTICH and POR, not the 

USB_OTG1_VUBS.

Wish it helps you!

Any updated information, please kindly let me know.

Best Regards,

Kerry

[Edgard]

Dear Kerry,

thanks for your prompt replying.
From now, I'll check the circuit diagram around Power-Up sequence concerned.

Kindest Regards 

 Edgard

[kerryzhou · Accepted solution]

Hi @Edgard ,

  Do you totally refer to the RT1020HDUG:

https://www.nxp.com/webapp/Download?colCode=MIMXRT1020HDUG&location=null

You need to follow the below DCDC circuit design:

The power on sequence is also very important:

Please check the above points at first, your test result means your DCDC is not work, you can check the power on sequence, whether it matches the above wave.

Wish it helps you!

Best Regards,

Kerry

[Edgard]

Dear Kerry,

I found that 5V power was wrong.

I used VBUS to supply +3.3V, but inrrush current sometimes occurred.

Then Power Source (PC side)  stopped the current to protect my target system.

Thanks for your advice!

Kindest Regards
 Edgard