28 Pin eeprom chip switch

[pietercc]

New here, not sure if this is the right category for this, I am looking for something to make it easier to swap in between two 28pin memory chips, as in have the 2 pugged in, and just have a toggle between the two. The chips I am looking to swap between are both 27sf512, Not sure what else to say, just curious if someone can point me in the right direction.

 

[Martaine2005]

Hi, you may be able to simply stack them and ONLY switch the VCC.
Or if on perfboard, use sockets for the ICs and only switch the power input (VCC)?

Martin

 

[Harald Kapp]

ONLY switch the VCC.

I beg to disagree.

That'll leave the unpowered switch with logic signals at the inputs. Undefined behavior will be the case.
Better to switch the [imath]\overline{CS}[/imath] signal like so:

This is how it's meant to be connected. The inactive Chip will drive its outputs to a high-Z state and thus will not disturb the output signal from the active chip.

 

[pietercc]

I beg to disagree.

That'll leave the unpowered switch with logic signals at the inputs. Undefined behavior will be the case.
Better to switch the [imath]\overline{CS}[/imath] signal like so:
View attachment 63091
This is how it's meant to be connected. The inactive Chip will drive its outputs to a high-Z state and thus will not disturb the output signal from the active chip.

Sorry I am getting back on this so late, the data sheet doesn't seem to have a CS pin, though I do see a CE, would that work to switch it?

 

[Harald Kapp]

CE = Chip Enable
CS = Chip Select
These are essentially the same.

 

[hevans1944]

There is also an active-low OE = Output Enable pin that you must use if paralleling the outputs (recommended).
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