Author Topic: Replacing SRAM with NVRAM  (Read 4232 times)

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Offline ZotDitzMyoTopic starter

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Replacing SRAM with NVRAM
« on: August 23, 2012, 09:59:46 am »
Hello,

  I was recently on the receiving end of an old Peavey Pro Fex II guitar Fx module. It has an onboard SRAM chip (Sony CXK58257AP-10L) and a Varta NiCd Battery that has leaked all over the place. After looking on the net, this seems like a common thing.

  I found someone who used to replace the battery/SRAM combination with only an NVRAM chip (ZMD  CXK58257AP-10L). Now it looks like ZMD was bought out by SimTek which was bought out by Cypress and I can't find suppliers of that part.

How would I go about finding a newer/available NVRAM chip to drop in the circuit? From the specs I need a 32K x8bits in a 300mil DIP28 package with at least 100ns access time.

How would you go looking for a part like this? what sites would you recommend?

thank you!
 

Offline Short Circuit

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Re: Replacing SRAM with NVRAM
« Reply #1 on: August 23, 2012, 10:46:17 am »
Almost match, this seems. Not in DIP, but you can get adaptors pcbs to get around that;
http://www.ramtron.com/products/nonvolatile-memory/parallel-product.aspx?id=132
 

Offline ZotDitzMyoTopic starter

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Re: Replacing SRAM with NVRAM
« Reply #2 on: August 23, 2012, 01:36:40 pm »
Thanks! This sure looks like a viable candidate.

I guess I`m still stuck in the 80s and  was looking too hard for DIP packages :-)

I read that the original chip replacement required a 10K resistor between pins 27 (!WE) and 28 (VDD) to prevent problems on power-ups. I am not at all familiar with memory chips, so I guess I will just try it out and see if it works!

Thanks gain!
 

Offline westfw

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Re: Replacing SRAM with NVRAM
« Reply #3 on: August 23, 2012, 04:43:18 pm »
Dallas semi used to be a major player.  They were acquired by Maxim.  It looks like the ds1230y is still available (sticker shock!)

http://para.maxim-ic.com/en/search.mvp?fam=memory&489=NV%20SRAM&232=Yes&tree=memory
 

Offline amyk

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Re: Replacing SRAM with NVRAM
« Reply #4 on: August 24, 2012, 08:30:02 am »
^ And there's also TI's offering, the bq4011.

A quick search for "32K x 8 nonvolatile sram DIP28" comes up with a bunch of possible parts, like

Cypress STK16C88
Cypress CY9C62256
FM28V020

...none of which are exactly cheap, but the expectation is that these parts shouldn't need to be replaced often.
 


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