Dear OliverChen,
Our board design was done with ODT impedance 48 ohms for LPDDR4.
However, I can not find 48 Ohms in RPA and MSCALE_DDR_Tool_User_Guide provided by you.
RPAv23 :
DDR_Tool_User_Guide :
That seems to be the case in the LPDDR4 data sheet.
Does DDRTOOL work correctly when I set 48 Ohms in RPA?
Best Regards,
George
Solved! Go to Solution.
Hi george,
Yes, you can use 48 ohm as the ODT impedance and the DDR tool can support it. The RPA tool and guide would update it in the future.
B.R
Oliver
Hi george,
Yes, you can use 48 ohm as the ODT impedance and the DDR tool can support it. The RPA tool and guide would update it in the future.
B.R
Oliver
Dear OliverChen
Tell us more about TxImpedance and ATxImpedance.
We compared it to IBIS-Model for i.MX8M.
DDR_Tool_User_Guide :
IBIS-Model :
[Model Selector] DQ_DQS
Driver Settigs = TxImpedance@RPA
mal4drv_lpd4_34 LPDDR4 mal4drv27 cell Z0=34-Ohm Driver
mal4drv_lpd4_40 LPDDR4 mal4drv27 cell Z0=40-Ohm Driver
mal4drv_lpd4_48 LPDDR4 mal4drv27 cell Z0=48-Ohm Driver
mal4drv_lpd4_60 LPDDR4 mal4drv27 cell Z0=60-Ohm Driver
[Model Selector] CA_CK
Driver Settigs = ATxImpedance@RPA
mal4drv_lpd4_30_ca LPDDR4 mal4drv20 cell Z0=30-Ohm Driver
mal4drv_lpd4_40_ca LPDDR4 mal4drv20 cell Z0=40-Ohm Driver
mal4drv_lpd4_60_ca LPDDR4 mal4drv20 cell Z0=60-Ohm Driver
mal4drv_lpd4_120_ca LPDDR4 mal4drv20 cell Z0=120-Ohm Driver
The number of impedances prepared for each is different.
which one is correct?
BR,
George
Hi george,
I'm sorry to make you confusion. The note in DDR_Tool_User_Guide document is complete and correct.
B.R
Oliver
Hi george,
Although in public release, we only list the input parameters as you saw, you can use all other possible values in your test. The DDR firmware support all of them.
B.R
Oliver