Hi Everyone I'm building a multiplexed Nixie clock with an Atmel XMEGA256A3B for brains and a K155ID1 as cathode decoder/driver. The problem is that the XMEGA is modern and wants 3.3V supply while the K155ID1 needs 5V.
The simplest solution I can think of is supplying both chips with 3.3V and hoping for the best. Altough I don't read russian, I can tell from the data sheet that the logic levels should match surpricinly well, but I cannot tell whether the rest of the circuit functions properly with a lower than expected supply voltage. I have limited capabilities to test the circuit properly (with nixies, cathode driver and microcontroller etc.) and therefore I wonder if anyone at Neonixie has used the K155ID1 like this before. I guess that the question is pretty generic really; is it possible to run a (early generation) TTL circuit at 3.3V reliably? Keep in mind that I don't require very quick switching, kilohertz are just fine here. The next step would be to add a 5V-regulator just to feed the driver. In that case, how/do I need to protect the outputs of the microcontroller? I have looked into the 'standard' schematics for TTL and it seems to me that a TTL input with a 5V supply would tend to pull its input high, possibly destroying a 3.3V output. Is series resistors sufficient or are transistors needed too? Another thing I just spotted is that the XMEGA have very versatile outputs, offering totem-pole, open-source and open-drain modes. Would a wired-and or wired-or be helpful for level-shifting? Kind regards Anton -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
