I know this is probably a broad question, but actually I am hoping for a broad answer in this case.

I have a microcontroller for which I need some external SDRAM memory. Let's say the memory's density and configuration is supported by the given microcontroller. Does the package type and number of pins (i.e. 86-pin TSOP or 90-Ball TF-BGA) still matter or can I just choose whatever is cheaper/smaller/fits the PCB?


closed as unclear what you're asking by Chris Stratton, Finbarr, Edgar Brown, Sparky256, Whit3rd Feb 17 at 11:26

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    \$\begingroup\$ If you need one of the pins that the 86-pin package leaves out, then you'll need the 90-pin one. Other than that I'm pretty sure the two should be identical. \$\endgroup\$ – Hearth Feb 11 at 12:10
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    \$\begingroup\$ Apart from the above: I would do trail PCB layout (paper & pencil) to see how easy/difficult the routing is. \$\endgroup\$ – Oldfart Feb 11 at 12:51
  • \$\begingroup\$ External RAM on a microcontroller is very rare, typically by the time that much memory is needed one is more in the territory of an SoC which is often cheaper. \$\endgroup\$ – Chris Stratton Feb 11 at 15:27
  • \$\begingroup\$ @ChrisStratton unfortunately that decision is not for me to make \$\endgroup\$ – nilleeee Feb 11 at 15:38
  • \$\begingroup\$ What you are trying to do, and your question about it puts your project in an odd corner of the possibility space. Designing a board with external memories, especially something like SDRAM, is typically only a project that should be undertaken by the experienced - in which case there would be an awareness that while there are a lot of concerns you need to consider in interfacing an SDRAM with a processor, the package matters only in how it might influcence those, not in an of itself. Your other question indicates the basics of SDRAM are still unfamiliar, this project may be a bit premature. \$\endgroup\$ – Chris Stratton Feb 11 at 16:16