Relaxing LPDDR4 timings for high temperature

[frank_vanhooft]

We're using an iMX8-mini with a single LPDDR4 x32 device. We're working on qualifying second and third source LPDDR4 chips, and having a little difficulty with some parts when running memtester at high temperature (75 C ambient or higher). We're using industrial-temp or automotive-temp parts rated for 1600 speed grade. We run the imx8 DDR interface at 1500 (as configured in the RPA spreadsheet). At high temps we still see the occasional memtester error with certain RAM chips.

In the RPA spreadsheet, I've selected "option 2" for the LPDDR4 MR4 manual de-rate workaround.

I'm looking for suggestions regarding which parameters I might change in the RPA spreadsheet to accommodate looser timings for the RAM, to help it at the higher temperatures.

Thanks.

[frank_vanhooft · Accepted solution]

I'm going to close this. I contacted an NXP guru, who pointed me to this:

https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/iMX-8M-Mini-Register-Programming-Aid-DRA...

That gave us the pointers we needed to move forward. We have the part working at high temps now. Thanks.

[frank_vanhooft]

-40 to +105C

Alliance AS4C256M32MD4-062BAN

[Rita_Wang]

At high temps we still see the occasional memtester error with certain RAM chips.

Could you share the full log  to us?

[Rita_Wang]

How about the temperature range of the DDR you are using?