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Hi,
Good Day.
I have a question about the VREGENZ signal (pin J18) on the processor. The data sheet says that this feature is not supported. However, the pin has an internal pull-down resistor, which enables it. What happens if we leave it unconnected? Does it try to use an internal linear regulator for the VDD (1.2 volts) supply? Will there be any harm if we drive the VDD from an external power supply and override the internal regulator?
Please advise. Thank you very much.
Best Regards,
Ray Vincent
Hi Ray, per the datasheet signal descriptions section, the pin must be connected to VDDIO. The internal pulldown is weak so failing to tie VREGENZ to VDDIO could cause instability (i.e. the VREG could become enabled or disabled unexpectedly under different operating conditions). Further, when enabled the internal VREG would be in contention with the external supply since they will never be precisely the same voltage. All this could cause expected behaviors in the device as the supply current fluctuates from the VREG turning on and off and sinking/sourcing as it contends with the external supply. I hope this helps explain the requirement specified in the datasheet.
Regards, Joe
