While in DDR3 datasheet, tRAS MAX is 9*tREFI, but in AM335x TRM it is fixed to 15 for DDR3?
This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
While in DDR3 datasheet, tRAS MAX is 9*tREFI, but in AM335x TRM it is fixed to 15 for DDR3?
I might add that your comment about the DDR3 datasheet: "tRAS MAX is 9*tREFI" is not correct.
The correct parameter is: "tRAS is 9*tREFI"
Even so, what is the problem here? The TRM and the AM335x_DDR_register_calc_tool.xls Excel sheet are quite specific that tRAS MAX must be set to 0xF. There is another parameter, tRAS in the Excel sheet, that must be set to the tRAS MIN time from the DDR datasheet, in nanoseconds.
Customer and their DDR vendor asks why TI fixed it as 0xF although DDR device specified it as 9, they concern the stability as it a refresh interval parameter.