1 Reply Latest reply on Mar 21, 2018 8:09 AM by weston_beal

    DDR2 batch simulation


      Hi all,

      I am performing a DDR2 batch simulation.I am assigning the IBIS models to DDR2 and controller. I have assigned prog buffer 2 model to controller MPC 8323. Address and control nets which are to be configured as output are being configured as input. Model assignment is not being done properly. Please suggest me how to configure the address and control nets as output.


      Controller pin: U1.AD11  (MEMC_MCAS_B)  --Model is input only, but needs to be output or I/O

      I am also facing another issue which says model does not have receiver thresholds section.


      Model does not have a [Receiver Thresholds] section.

      Missing Vinh and Vinl thresholds in the [Model Spec] section.

        • 1. Re: DDR2 batch simulation



          The first problem is most likely related to the Model Selector setting. As you work through the DDR Wizard there is a page for IBIS Model Selectors. On this page, you should see Model Selector rows for ADDR and CMD. They might be separate rows or they might be together. The name is shown as in the IBIS file, so I don't know exactly what it is. Look at the text of the IBIS file to see the comments after the model names in the [Model Selector] section. The comments might indicate if each model is an input or an output. If not, you can look at the text of each model to find its Model_type parameter. Then you can assign an output type model to the address and command model selector in the DDR Wizard.


          The second issue with the [Receiver Thresholds] is fairly common. The JEDEC specification for DDR2 says that receivers should have AC and DC input thresholds, but some controllers either don't use the technology that supports these or just forget to put the information in the IBIS models. If the datasheet includes this information then you can add it into the IBIS file. Otherwise, you can ignore the errors, but realize that the results have some small unknown error because of the simplified input threshold data.