Am Mon, 28 Aug 2017 17:27:53 +0200 hat "H. Nikolaus Schaller" hns@goldelico.com geschrieben:
Hi,
One more info from the distributor: As Dual Die chips basically have twice the load, the might need a different combination of resistors and capacitors than Single-Rank chip.
Well, this means signal load i.e. resistors and capacities inside the chip (Si on SiO2 forms resistors and inductors and capacitors as well). So we can't change those.
Ah, okay. Well, signal integrity is fine, so that's not the problem. Or would increasing the driver strength help with noise on the power traces as well?
Can the driver strength be increased by software?
notaz mentioned the EVM has over 44 capacitors for the RAM power traces only... how many do we have and can those be changed / optimized?
What can be changed is the drive strength on the OMAP side. This is more or less equivalent to changing driver resistance. In other words: higher driver strength sends stronger signals and this charges/discharges capacitors formed by the Si chips in the DDR3 Multi Chip package faster. Faster charge/discharge gives better signals (usually) and more room for timing misalignment.