Electronics > Projects, Designs, and Technical Stuff
Does PSRAM get outdated?
ace1903:
I looked for easy PCB design and small high throughput interface and found this:
https://www.cypress.com/file/498621/download
Looks like DDR memory but with the only dozen high-speed lines.
Never went to make actual design with it. QSPI sounds nice but is not standardized well and accepted among silicon vendors.
PSRAM was a thing 2006 and quickly forgotten. Beside espressif no one else uses actively.
But when memory prices went up, some Chinese companies used old technologies and foundries to fill the marked gap.
Benta:
--- Quote from: soFPG on July 20, 2020, 01:20:09 pm ---The time I looked at some PSRAM datasheets I noted that SPI would run at ~133MHz (often QSPI capable).
So bandwith shouldn't be a problem (probably why espressif's ESP32 uses SPI for external flash as well as for external PSRAM).
I am not talking about 4k video but rather about something like 640 x 480.
--- End quote ---
Dunno how much bandwidth you need. QSPI would give you around 20 Mbytes/s maximum (and that's probably even too optimistic).
BrianHG:
You've got a wide selection. Be careful as some like the Hyperbus variety have half the access time making them better.
Like others have said, unless you are trying to save IO count, a DDR2/3 ram would just be easier.
Also, everything is going BGA as seen by the selection here:
https://www.digikey.com/products/en/integrated-circuits-ics/memory/774?FV=961%7C390622%2C-8%7C774&quantity=0&ColumnSort=1000011&page=1&stock=1&nstock=1&k=psram&pageSize=100&pkeyword=psram
Though, the most common 48-FBGA (6x7) 1mm BGA is easy to mount as it is so small.
The 44-TSOP is available, but I do not know for how long.
soFPG:
--- Quote ---Dunno how much bandwidth you need. QSPI would give you around 20 Mbytes/s maximum (and that's probably even too optimistic).
--- End quote ---
Dunno how you calculated that value. 133MHz * 4 data lanes (QSPI) = 66Mbyte/s
Even QSPI Flash is able to transfer 50 Mbyte/s: https://www.winbond.com/resource-files/w25q128fv%20rev.l%2008242015.pdf
--- Quote ---Like others have said, unless you are trying to save IO count, a DDR2/3 ram would just be easier.
--- End quote ---
I don't think I am going to make a DDR2 or even DDR3 design any time soon. I'll stick with SDRAM for now, thank you.
Scrts:
You can also have a look into Cypress HyperRam, which is 24 balls BGA, 5x5mm package. Works in Octal SPI mode as well:
https://www.cypress.com/file/498616/download
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version