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Hi Champs,
According to XILINX Answer Records #36104, CKE signal is required an external pull-down with a 4.7 kOhm resistor connected to GND to adhere to the DDR2 Spec to drive it to low during RESET as below.
o XILINX AR# 36104
(http://www.xilinx.com/support/answers/36104.html)
- Description
The Memory Controller drives the ODT, CKE, and RESET signals during normal operation
and LOW during initialization, but a pull-down with a 4.7 kOhm resistor connected to
GND is still required to adhere to the DDR2 and DDR3 Memory Standards.
- Solution
Based off the Power-Up Initialization Sequence defined by the DDR2 Spec, CKE and ODT
are supposed to be maintained at a LOW state while applying power. To guarantee this
occurs while the FPGA is being configured (before it can drive CKE and ODT "Low") we
require the pull-down to GND.
So, Dose DM6437 DDR_CKE pin also need to have the 4.7 kOhm external pull-down resistor?
Thanks in advance for your cooperation.
Best regards,
j-breeze
The Memory Controller drives the ODT, CKE, and RESET signals during normal operation and LOW during initialization, but a pull-down with a 4.7 kOhm resistor connected to GND is still required to adhere to the DDR2 and DDR3 Memory Standards.
Hi Champs,
Any comments would be appriciated.
I'd like to know about if DM6437 DDR_CKE pin needs an external pull-down or not.
Best regards,
j-breeze