OT: 5V vs. 3.3V

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#1
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I know this question is off topic and I appologize beforehand. This is an issue that many good hardware people here are facing I'm guessing. Please feel free to flame me if I've overstepped boundaries.

I've been aaaociated with a company and done many designs for them over the years (since the 1990's). over the years I have stanbdardized the use of many components to re-use what works and has been proven and to take advantage of economies-of-scale. However, the 5V SRAM I've designed into many products is dissppearing. Alternatives from companies like Renesas do not appear to be readily available from distribution.

I have decided that I have been beating a dead hiorse rtrying to find an 8Mb 5V LP X16 SRAM and I should use a newer 3.3V part with level translators.

A quick search a few weeks ago turned up only a few translators - single channel ones on so8 for instandce. Has anyone come acrosss a jellybeen 5V to 3.3V translator line that comes in octal or 16 channel densities?

DFR

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Maybe a cpld ...

Xilinx makes some that are 5v tolerant , and then you get the latch for free :-)

Else the word BusSwitch would be the thing to search for

/Bingo

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Hi,

check Fairchild´s 74LVX(C)4245 and 74LVX(C)3245 for the databus (bidirectional).
for the addressbus you can use any 5V tolerant driver (one direction).

Check also PLDs/FPGAs with 5V tolerant inputs. This can decrease part count. (i use the XILINX XC95..XL - not that expensive)

Klaus
********************************
Look at: www.megausb.de (German)
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Bingo600 wrote:
Maybe a cpld ...

Xilinx makes some that are 5v tolerant , and then you get the latch for free :-)

Else the word BusSwitch would be the thing to search for

/Bingo

Thanks! I was just looking at xilinx XC95 line with the same thought in mind. I'll now go and search for Bus Switchy!

DFR

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74LCX125 is a 4X buffer that is 5V tolerant when run at 3.3V. You can use it inverting or not, depending on whether you go in on the normal buffer input or the output enable pin. Very versatile and relatively cheap.
On Semi and others.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Dana have a look at XAPP073 - Mixed voltage operation

But do a search for XC95 and output voltage on Xilinx.

I seem to remember an errata complaining about the Voh of the XC95 cpld series

Found it : http://www.xilinx.com/xlnx/xil_a...

Some other info
http://www.xilinx.com/xlnx/xil_a...
http://www.xilinx.com/xlnx/xil_a...

cpld faq:
http://www.xilinx.com/xlnx/xil_a...

/Bingo

Last Edited: Tue. Nov 14, 2006 - 06:31 PM
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Isn't the 16-bit version of the TI 74LVCx245 something like 74LVC16245? I know there is a 16-bit version. I think there are 32-bit versions as well and maybe other sizes like 20 & 24.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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The best solution is usually to go all the way and use a 3.3V CPU as well.