CD4060 oscillator, max resistor value

No idea, wouldn't even know where to look. To be honest, I never cared as long as I could read it. All I know is the char set is Western-ISO.

The datasheet looks perfectly aware to me. With resistor values to 100M readily available, the 20M as a highest datasheet timing value is perfectly reasonable, if you assume input-leakage currents under say 10nA. In fact, the real-world CD-series CMOS device leakage currents are far below that. I have experience manufacturing instruments, using over about 2-million CD4000-series ICs, to attest to that. If one of these ICs actually has a high leakage current like that specified in some of the datasheets, then that IC is defective, IMO.

Joerg, can you use a low supply-voltage for the 4060? How high a temperature will your app be subjected to?

Win, I agree. Same experience here. Not sure how many millions but some stuff is now way past a decade and still in full production. Anyhow, what puzzles me on the CD4060 is that some mfgs state not to go above 1M while others say 20M is fine.

Temp will be whatever the indoor weather says (assuming many users won't have A/C). So 50F to 110F would describe it. Around 4V the cross-conduction spike nearly disappears but I can't have an extra rail plus level conversion for this, no space. It's all TSSOP, SC-75 and 0402 and chock full.

Do you know whether the CD4000 process got a spritz of Tabasco or other spice-up? It surprises me that they use such hard devices on an inverter that only has to feed 100K or so minimum and one input. Years ago I have seen cross spikes in the tens of uA but not a 400uA whopper like this, and at 10V no less.

What's your supply voltage? What do you measure for the cd4060 cross-conduction peak current with your oscillator circuit, and what's your average current?

CMOS leakage is "spec'd" so the manufacturer doesn't have to measure it during final test.

Why don't you measure a few at the highest temperature you expect to operate and draw you own conclusion/spec?

...Jim Thompson

VCC is 10V max. I'd have to look again but one of them was over 400uA peak and the average contribution from cross current was a little above

Oh, I know they'll be ok and I could measure it even though that will only be from one wafer. Of course, when you design for medical that startegy doesn't fly.

I guess we'll do the protos with the 4060 scheme and then go to a uC for the final. The downside of a uC is its narrow voltage tolerance range and consequently the need for a regulator. Plus some level translation. Cost is another issue, it's amazing how little dozens of discretes cost these days. A resistor can weigh under a penny including SMT placement.

Joerg, Try....

Newsgroups: alt.binaries.schematics.electronic Subject: Re: CD4060 oscillator, max resistor value (From SED) - Oscillator-ModifiedOldStyleCMOS.pdf Message-ID:

except use your 4060 devices, and see what you get.

...Jim Thompson

How about a series resistor and bypass cap or zener etc to reduce the voltage?

That can be done but it would mean I'd have the current flowing all the time, not just when the counters run. One is held at times, not only via reset but also the oscillator itself. Also, then I'd need level translators and there just ain't any space. Even a mosquito would not be able to land between parts on that flex board.

Will try. Thanks!

Yeah, keyboards are a pretty amazing marriage of cheap and reliable. Also they have an incredible capacity for dirt. The Cherry I'm typing on looks positively revolting when I peek between keys...

robert

Plenty of tap water with soap followed by a liberal application of heat works wonders with consumer electronics. Most people just wouldn't dare doing it.

It didn't work with my old PalmPilot though. I did manage to resurrect it after a bath in something sticky, but now it goes through a set of alkalines in a week instead of a year. I tried distilled water and then isopropanol in an ultrasonic bath to no avail.

robert

Conductive ink? I once installed 24 DIN4162 96/96 connectors on a 6U 4-layer backplane. Used flux cleaner to clean it off. To my horror there was significant leakage resistance between most adjacent pins on the connectors. It was caused by the ink used to ID the connectors, dissolved by the flux cleaner. It took days (and days) of repeated soaking and air-blasting to shift that ink from between the backplane and connector bodies.

Watch out. Once you see a street of ants between your keyboard and the main entrance it's time to take it apart and clean it :-)

Sometime, pick it up, turn it face down, and tap it on the desk.

That's especially fun if you're a smoker. ;-)

You must have been tearing apart a very old keyboard - these days they have about three parts:

Cheers! Rich

Or toss it out and pick another from the 100+ spares. :(

Feh? Keyboards are so cheap. How can you afford the time to disassemble?

...Jim Thompson

That's my technique. I replace PC's faster than keyboards, and every new box includes a keyboard for free.

...Jim Thompson