DDR IBIS model selection

AN3099

10/13

Doc ID 16605 Rev 1

Note:

In Bold the fixed bx bit values for the STM DDR2 application board.

Figure 2.

CLKP signal simulation case (for example) with the HyperLynx tool

As shown in Figure 2, if the simulation tool supports the model selector function, it’s pretty

easy to select the right model. When you select the pin name of the package (ball name) to

be used in the simulation, the tool points automatically to the signal name and shows the

model group name, listing in a window all the models contained in the group. As you can see

in the model selector windows, all the models with all the available combination of the 7 or 8

bits are presented.

Knowing the operational mode or the content of the two registers explained in the previous

paragraph, you can select the right model to be used by the simulation. In this specific

example the selected model is BDCLK_R_IN_11000110.

There are simulation tools that do not support the model selector function. In this case, you

must probably manually remove from the IBIS model library all the models with the bit

settings that are not used in the simulation, only leaving in the library the models with the

combination of bits related to the used operating mode.