AnsweredAssumed Answered

DDR Refreshing Rate

Question asked by Akash Nair on Oct 7, 2019
Latest reply on Oct 10, 2019 by Yuri Muhin
We are keeping i.MX6ULL based board at 85°C constant for 16 hours. At this point, we have kept a check at U-BOOT continuously monitoring the MPU core/junction temperature. Also, DDR's 1.35V & MPU's core voltages SOC_IN & High_IN are ON and all other rails are kept OFF. We observed that after some hours every supply gets down to 0V i.e. SOC_IN and HIGH_IN go to 0V, VSNVS is still 3V and PMIC_POWERON_REQ goes low. Hence the PMIC goes to power off mode. 

On researching and analyzing some datasheet and reference manual we found that in the datasheet of DDR[MT41K128M16JT-125] it is mentioned that, If Tc exceeds 85°C, the DRAM must be refreshed manually at 2x refresh, which is a 3.9μsinterval refresh rate.
Que 1: How to manually refresh DRAM at 2x? Since we are at U-Boot how to do it from U-BOOT?
Que 2: It is mentioned in Datasheet that on enabling ASR, DRAM's self-refresh rate is changed automatically from 1x to 2x. So How to enable it? Is there any register that we should access for changing this manually?
Que 3: Is it advisable to manually refresh it at 2x? Are there any other consequences if the refresh rate is doubled?
I have attached the snapshot from the DDR datasheet regarding the refresh rate.