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EMMC unexpected VCCQ supply 1.8V to 2.3V behavior.

Question asked by Peter Amond on Oct 23, 2017
Latest reply on Nov 1, 2017 by TomE
Hi All,
This is regarding i.MAX6Q based custom hardware design and this design most similar to Nitrogen 6_Max development board. We are using MTFC4GLDDQ-4M IT micron emmc.
We had an issue with EMMC, VCCQ 1.8V supply and it increases up to 2.3V unexpectedly. And we could recover this happens when EMMC configured via u-boot and come to a certain state(Reset). 
There are 2 supplies for EMMC
VCC Supply (3.3V) = NAND interface I/O and NAND Flash power supply.
VCCQ Supply (1.8V) = e·MMC controller core and e·MMC interface I/O power supply.
We are using SD4_DATA signals for DATA signals of EMMC from i.MAX (According to above figure) and for those signals i.MAX power block is NVCC_NANDF which can go up to 1.65V to 3.6V range. And we are giving 3.3V for this block. (But in Nitrogen 6 MAX it is 1.8V)
From i.MAX side processor generates signals in 0V ~ 3.3V range.
From EMMC side the e·MMC controller core and e·MMC interface I/O power supply control 0V ~ 1.8V range.
We think this will make conflict inside EMMC and 1.8V suuply override with 2.3V due to mismatch of I/O signal voltage range from processor side.
Can you give a comment on this ? Does our conclusion correct ? Any other reason to happen this kind of issue ?
Regards.
Peter.

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