RT1052 USB_OTGx_VBUS leakage

[sinu52]

Hi,

I have a question regarding a leakage path from the USB_OTGx_VBUS pins to the 3V3 rail.

When connecting a powered USB cable to our unpowered device containing the RT1052 we can measure the 3V3 rail being pulled to 1V indicating a leakage path within the RT1052 MCU. Will this cause an issue for powering up the MCU?

The datasheets states the following regarding this:

1: "USB_OTG1_VBUS, USB_OTG2_VBUS, and VDDA_ADC_3P3 are not
part of the power supply sequence and may be powered at any time."

2: "Need to ensure that there is no back voltage (leakage) from any supply on
the board towards the 3.3 V supply."

Kind regards,

Remco

[diego_charles]

Hi @sinu52 

I hope you are doing well, I am very sorry for the late response. 

General response, is to avoid this kind of scenarios, and therefore any further HW errros. 

Could you indicate me which MCU rail is being pulled up? Also, did you get this from our I.MX RT1050 EVK?  I can try to reproduce and measure this on our board, so we could determine further if this is may have an impact.

Below snapshots from the RT1050 rails and power supply sequence. 

All the best, 

Diego