At 06:36 PM 12/4/2008, you wrote:
>Hi guys,
>    I'm currently designing a piece of kit that includes a 
> PIC18F4550 (USB PIC)
>and an FPGA. The PIC is running at 5V (I need the 48MHz core clock), but the
>FPGA's Vio voltage is 3.3V. Comms between the two devices is done with the
>Streaming Parallel Port. So I need a level translator of some description...
>
>    While I've found a bunch of level translators that are available in SOIC
>and TSSOP packaging (most notably the 74LVC4245 from TI, and the more
>expensive Fairchild clone of the TI part), I haven't found any octal level
>translators that are available in a PDIP package.

Not in PDIP. Not a single one I know of.

I use lots of 74lvcc3245, lvcc4245, and 74hc8t245 as well as many 
others. But a search of the TI website should show none of them in 
DIP packages.

But you can use a resistive divider on the input pins - unless the IO 
pins are 5V tolerant and it is a fdair bet they are not. For the 
FPGA->MCU use something like a 74HCT245 - it MUST be a T, because 
when driven with 3.3V IO it will properly run on a 5V rail. I do that 
a lot where I have things like 74HCT541, 74HCT245 or 74HCT138 on 5V 
but the FPGA is on 3.3V.

John


>    Does anyone know of anything like this, or am I asking for unobtainium?
>
>    Thus far I've wasted about an hour digging through Farnell's atrocious
>stock database, and found the LVC4245 (which I already knew about) 
>and nothing
>else. Specifying "Package: PDIP" immediately eliminates every single search
>result...
>
>Thanks,
>--
>Phil.
>piclist@philpem.me.uk
>http://www.philpem.me.uk/
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>12/4/2008 8:05 AM

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