Thanks for the reply. I managed to get it all working.There's nothing particular to do to select between these devices - they should both work equivalently for programs smaller than 2Mbyte.
One possibility is that they aren't W25Q16JVUXIQ but something similar - the markings on the top of the devices should tell you if you've accidentally got the wrong parts. According to the datasheet, this should be two lines - "1Pyww" (containing year and week datecode) and "0Mxxxx" batch number. Some that I bought a few months ago read "1P250" "00219L".
Alternatively, are you sure you had the footprint right and haven't quietly corrected the mistake with your patch wires to the larger chip?
I hadn't fitted all the capacitors because I was just fitting the components to my board which should have been barebones enough to test. Funnily enough it was for the W25Q128JVSQ but not the W25Q16JVUXIQ. The W25Q16JVUXIQ seems more picky about voltage stability and/or maybe noise. After adding all of the decoupling capacitors, 2.2uF AND 100nF capacitor for the W25Q16JVUXIQ and remaining capacitors such as those on the 5V input and 3V output, everything works.
Moral of the story is, fit all components before assuming its not working. Although it's still strange how W25Q128JVSQ was able to work with all of those caps missing. It seems less fussy.
Statistics: Posted by DoubleK1LL — Fri May 31, 2024 10:54 pm