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Does it need to pull up CS3#, Data Bus, RAS#, CAS# and others using SDRAM?

Latest Updated:09/28/2009

Question:

In the case of SDRAM usage, does it need to pull-up CS3#, Data Bus, RAS#, CAS# and other pins?

Answer:

These pins will be INPUT ports at RESET release timing. But their level will be fixed to High or Low by the weak keeper circuit. If you want to fix a pin speciically to alevel (High or Low), you need to pull-up/pull-down the pin using the external circuit. For example, CS3# needs to be fixed to High level when it does not access SDRAM. It is recommended that this pin be pulled up using a 2k ohm register. Other pins are same. To prevent malfunction until the pin can be set, it is recommended that it also be pulled up/down as needed.
Suitable Products
SH7619
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