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iMX Power Up problem (VDD4P2)

Question asked by Fernando Luis on Feb 8, 2013
Latest reply on May 1, 2013 by Alfred Liu
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Hi all,

 

In a custom made board with the iMX280 I have the trouble (when powering up) that the lin regs values are wrong. VDDD and VDDA are near the same, about 1,7V. And this is out of sense value for VDDD. Also, at VDD4P2 I'm just obtaining 0,6V (I see with multimeter that voltage on this raises not very fast).

About my BATTERY, DCDC_BATT, and VDD4P2 connections... are just the same as in the EVK rev. D. I have no battery connected.

 

The thing is that I had to change the iMX280 processor (the BGA) by a new one in my board yesterday. And now is when I'm getting this wrong values in VDDIO (just 3V), in VDDD (1,7V :-0), and in VDDA (1,73V) -so I know that the design of this part is right-.

The VDD4P2 value was always wrong. I can never get 4.2V.

 

As said, the wrong values are when connecting the power... I have not even the opportunity to burn the NAND.

 

I revised all... no shorts, capacitors ok, schottky diode between VDD4P2 and BATTERY/DCDC_BATT ok, so I don't know what else to revise. Can be a problem of the inductor between DCDC_LP and DCDC_LN??... because I have no battery connected??...

 

Thank you very much!!

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