23LC1024 and 25LC1024 packages

[ggchab]

Surprisingly, the Microchip 23LC1024 is available in SOIC package while the 25LC1024 is available in SOIJ package (a bit wider). I am wondering why they use different packages for similar chips. In fact, I was planning to use the same PCB layout for both types of chips and then decide which one and how many to solder, depending on the usage. The solution is probably to make pads a bit longer, but why this difference ? Thank you.

[mash107]

It's probably due to the larger size of that particular die needing the extra area. The 25LC1024 is a non-volatile memory (saved contents after power off); as such, it needs special features, like a charge pump. Its cell structure is also different (i.e. larger) to ensure data retention vs the volitaile SRAM (23LC1024).

I like Onsemi's serial EEPROM solutions, as they offer a smaller die that can fit in the narrow SOIC body: http://www.onsemi.com/pub_link/Collateral/CAT25M01-D.PDF

[ggchab]

Thanks for the suggestion. Perfect for my PCB as it has the same pin configuration