5V FPGAs & CPLDs in 2006?

What would people's opinion on using a 5V FPGA (or possibly large-I/O-count CPLD) for a new, but limited run in-house-product in this day and age be? This would be a USB-tethered lab/ATE/field-service/etc "universal interface" intended to replace some aging parallel-port driven devices not supported by modern PCs (especially laptops).

The reason for a 5V part is that performance demands are very low, but it needs to interface with up to about 100 bits of 5v instrumentation control bus, driving as well as receiving. If I use a part with a 3.3v I/O voltage I need level translators. That means a much more complicated board. I realize not using translators exposes the FPGA to greater risk of damage from the outside world, but now that we have a good rework station changing out one blown FPGA isn't that much worse than changing out multiple blown translators.

I'd also like to avoid the level translators to ease reconfiguration - I believe I can use the same FTDI USB chip to JTAG program the FPGA in addition to talking to it, and that would let my device driver download an appropriate FPGA configuration for any of our applications, which might need to change which pins are inputs or outputs on a bit-by-bit basis rather than the byte-by-byte basis most translators would support.

Other than making sure to buy enough chips + spares up front, any reason not to use an older part like an original spartan? Any particular 5v devices with 100+ I/O's in non-BGA packages that might be more likely than others to hang around?

Reply to
cs_posting
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cs_posting,

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Is still right there, online, and up front. So yes, a new design with a

5V Spartan 4K part is not only do-able, but supported.

Not sure what software supports it, but we always have the last version of software available for folks through our support web pages. I suggest you be careful about what schematic editor you choose, as I remember that we had a schematic editor that we needed to obsolete, as the vendor no longer would support license for its use.

If you look through the notifications of "end of life" or "discontinue"

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You will find that there are some part/packages you should avoid.

Given that, I think you can negotiate your way to obtaining sufficient supply, and support for a product without fear of getting caught in a situation of "no parts" for quite awhile (perhaps more than five years).

When you choose a part, then you can register for any notifications, so that you will have an opportunity to place a "last time buy" order before you are in trouble.

Sometimes, the whole world is not the right voltage.

Hope this helps.

Aust> What would people's opinion on using a 5V FPGA (or possibly

Reply to
Austin Lesea

Austin Lesea schrieb:

5V Instrumentation busses can also be interfaced to with a Spartan-II. Albeit using 3.3V as VCCIO the inputs are 5V tolerant and 5V TTL only requires the output to be driven to 2.4V so you get full TTL compliance. While the 3.3V are not 5V CMOS compliant, the resulting 0.8V noise margin should be enough for most applications.

Kolja Sulimma

Reply to
Kolja Sulimma

I want to actually drive it at close to 5v - otherwise yes there are many choices.

The problem with using a Spartan "0" is figuring out how far back in the history of the tools one must delve to find support...

Reply to
cs_posting

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