What is the minimum clock voltage for a BBD to function?

[RLawlor]

I have some far-fetched ideas in my head of things I can do with BBDs... but it's all dependant on the required clock voltage  . I'm planning on using the V3205s and am wondering which of 5V, 3V3 and 1V8 logic levels would work, thanks.

[Mark Hammer]

Datasheet for the MN3102, normally used with any 32xx series BBD, says that its output voltage - which one may assume is the clock pulses - is 4.67V, using a 5V supply.  So 5V logic level comes closest.

[RLawlor]

Thank you very much, was looking to try out some CPLDs but they all come in different logic voltage levels.

[ElectricDruid]

The required clock input voltage depends on the supply voltage for the BBD. If it's on 9V supply, 9V clock, on a 5V supply, 5V clock, etc.

MN3207 datasheet gives the supply range as 4-10V, so presumably you could run it at 4V with 4V logic, but for typical logic voltages, 5V is pretty much your only choice. I suppose there's a chance the chips will run at 3.3V, but you'd be outside the spec so all bets are off.

[Scruffie]

The required clock input voltage depends on the supply voltage for the BBD. If it's on 9V supply, 9V clock, on a 5V supply, 5V clock, etc.

MN3207 datasheet gives the supply range as 4-10V, so presumably you could run it at 4V with 4V logic, but for typical logic voltages, 5V is pretty much your only choice. I suppose there's a chance the chips will run at 3.3V, but you'd be outside the spec so all bets are off.

You'd need an MN3305, not that I've ever seen one outside of the datasheet, 1.8V-5V supply.

[RLawlor]

The required clock input voltage depends on the supply voltage for the BBD

I'm sure there's some brillaint headroom at 5V  . I'll see if theres anything I can do to get it working with 9V, thanks.

[RLawlor]

I'm sure there's some brillaint headroom at 5V

Just did some quick research and it seems as though the MN32XX series are quite suited to running at 5V after regulation from 9V so this could work, great!

[Mark Hammer]

You'd need an MN3305, not that I've ever seen one outside of the datasheet, 1.8V-5V supply.

Me neither.  It's some sort of mythical beast.

[bushidov]

You can keep the BBDs at their normal 9-ish volts. Just use a voltage shifter IC or MOSFETs as discrete voltage shifters when going to and from your micro to your BBDs.

[ElectricDruid]

I'm sure there's some brillaint headroom at 5V

Just did some quick research and it seems as though the MN32XX series are quite suited to running at 5V after regulation from 9V so this could work, great!

Yes, they work fine at 5V. My flangelicious project runs the BBD at 5V so the clock can be generated by a PIC. Headroom is about 2Vpp through the BBD.

Running the BBD at 9V and using level-shifters of some type is an alternative approach, but I was trying to keep the parts-count right down for my own project so I avoided them.

[anotherjim]

If level shifting, clock edge speed might end up slower which in turn limits the BBD clock frequency. If you want to do flanging with 1024 stage BBD that could be a problem. However, with a 4096 stage, you won't be doing flanging.

Direct 5v operation will be easier and if the headroom proves a problem, you might add companding, which is what a commercial product would probably do.

[PRR]

> try out some CPLDs

If you want to run 1.3V logic into 110V neon indicators, use an "amplifier". For 3V-5V logic conversions, it is what Tom said, level-shifter.

As Jim says, no amplifier is infinitely fast so it will limit speed; but this is the 21st century. It is not hard to whomp-up something much-much faster than a 1977 commodity logic chip (mis-applied as a BBD).