3.3v <> 5v interfacing @ 15Mhz

You're exhibiting the same ignorance of how IC's work as Yuriy K.

...Jim Thompson

Hi Jim,

Nothing wrong with what you've said. It's all stuff I'm reading through so none of it is wasted :-)

thanks,

Alison

Thanks!

These _little_boys_ just get on my nerves chastising me and saying that HCT would work properly in your application.

...Jim Thompson

Now, now :-)

Everything everyone has said is valued. It's enabling me to build up a wider picture of what can be done and what the options are. What I do and don't do I won't announce though. :-) I'll go with what is reliable with my own eyes.

The trouble with the net is that since it's so *company* driven, there is only their view since it's so difficult now to Google search for the old fashioned diy and educational stuff. If only we could go back 10-years to when companies laughed at the Internet. Searching was a hell of alot easier before they came along. Usenet has calmed down alot too, we'd be threatening to murder each other with a pickaxe by now. (those were the days).

:-)

Alison

This is exactly correct.

Extra knowledge only hurts to the fools.

RTFM, dude.

It does mean that > 2.0V is guaranteed 1 and < 0.8V is guaranteed 0. The threshold is normally at 1.4V which is exactly what is required for

Oh, you don't say.

Have the courage to admit the mistake, dear.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

Your ignorance is very loud and of highest quality, I must admit. Not everybody can achieve that level. Have you ever read datasheet, or any textbook for the EE? "The Art of Electronics" would be a good start.

SN74HCT14

VT+ max 2.1V VT- min 0.5V

SN74HCT04

VT+ max 2.1V VT- min 0.5V

Other manufacturers have similar characteristics.

Typical 3.3V logic:

SN74HC04

VoutH min 3.2V @ 20uA VoutL max 0.1V @ 20uA

After all these years of design it is finally time to learn the basics. :)

Just go with a chip designed for the purpose.

...Jim Thompson

Hi Alison,

Thanks for the reply.

You might find breadboarding a lot more pleasant once you get the hang of working with copperclad. It certainly makes working with high frequency a lot easier, and a well-made board can even be used in place of a pcb. I like to use ordinary hot glue to mount components to the copper. This works great for parts that stay cool:)

I'm still using prototypes I made years ago, and they work fine.

Good luck with your circuit!

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:

Keep it up. Everybody is realizing the "value" of your consultancy ;-)

You read a data sheet without understanding.

...Jim Thompson

Hey f*****ad. I re-designed those parts for ON-Semi.

You are clueless as to good engineering practice.

...Jim Thompson

If you have something meaningful to say, then go ahead and tell us. Otherwise have the courage to admit that you just made a fool of yourself, my dear analog desiner.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

Correction: ViH min 2.0V ViL max 0.8V

A lot of noise, no information whatsoever. It is a sign of weakness and I forgive you. Be at peace with yourself.

Apply +2.4V Input to an HCTxx running on VDD = +5V and what happens?

...Jim Thompson

And piece be with you also... GFY ;-)

...Jim Thompson

Jim Thompson a écrit :

Well, you can't expect a digital guy to know that.

Hmmm, gave me an idea :-)

Nothing happens. The 2.4V reads as a clear 1, the threshold is at 1.4V

Jim , you goofed up and I suggest you to bring your apologies.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

Allowing a static (and *undefined* BTW... 1mA if you're lucky) current flow is NOT good engineering practice, and it's NEVER done in well-designed ASIC's.

To see how a 3.3V Logic Level to 5V Logic Level Translator is done properly (in ASIC's designed specifically for that purpose), see...

Dimensions are "pre-shrink" BTW, as if you'd know what that means ;-)

I used a similar scheme in my USB interface work for Intel. Unfortunately the patents don't show that part, since it's old art.

Expect my apologies about the time Russia actually becomes a Democracy and Iran becomes Jewish ;-)

...Jim Thompson

Also: Static current for this structure is zero, except for nA's of leakage.

...Jim Thompson

Jim, your schematic is lacking the power details. How are the HC04 powered ? +3.3V or +5V ?

Rene