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Hyper RAM

New Contributor

I working on some hardware that will use the S70K HyperRAM.

The hardware guide for HyperRAM, where it talks about layout requirements and such, makes a vague reference to using terminations if required. I don't have access to signal integrity tools so I have no way of knowing if the termination resistors will be required or not. My board will be pretty small (less than 1" x 2"), so I will place the RAM as close to the MCU as physically possible.

One of the demo kits for a microcontroller I am considering (STM32H7 variant) places series resistors at the HyperRAM pins only. As the data pins are bidirectional, I'm not sure why the terminations would only be needed in one direction (in this case RAM->MCU but not MCU->RAM).

Does anyone have any advice?

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Moderator
Moderator

Hi,

Generally series resistance in this circuit is used to match the impedance and dampen any overshoot or undershoot. The MCUs generally do not need any external termination as they have resources for internal termination if required and also the drive strength of the MCU pins will be higher than that of the HyperRAM. So the MCU will be able to source/sink higher current than the HyperRAM and does not require external termination as such.

Although it is always suggested to perform a SI analysis using the IBIS model to get the layout without any issues.  

Thanks,

Pradipta.

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Moderator
Moderator

Hi,

Generally series resistance in this circuit is used to match the impedance and dampen any overshoot or undershoot. The MCUs generally do not need any external termination as they have resources for internal termination if required and also the drive strength of the MCU pins will be higher than that of the HyperRAM. So the MCU will be able to source/sink higher current than the HyperRAM and does not require external termination as such.

Although it is always suggested to perform a SI analysis using the IBIS model to get the layout without any issues.  

Thanks,

Pradipta.

View solution in original post

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