I need to TI document explaining how to use and 54HC as a replacement for 54C

Steve Mcgowan

Other Parts Discussed in Thread: CD4012B-MIL, SN54F30, SN54AS30, SN54LS30, SN54ALS30A, SN5430, SN54S30, CD54HC30, CD54HCT30, LM109

Sir/Ma'am:

I need a TI engineer to respond on how to use a 54HC chip in a 54C application.

From the TI Logic roadmap one should be able to replace the power supplies to enforce 6vdc (if necessary) and then use 54HC devices. If the 54HC device is not available then we should be able to use 74HC devices.

Both chat and tech support said they can't answer the above (chat actually gave me a nonsense answer which I could not accept)

I asked for a supervisor on tech support since the person said they must open a ticket but started yelling at me for not accepting the chat answer below.

"As for the 54C used in placed of the 54HC, yes that is correct."

So I waited for voicemail only to be transferred to a number with no voicemail.

I cannot take a backwards answer and use that for taking risks with equipment in the field.

This statement seemed to infuriate the guy I was talking to. I guess he has a problem with the military.

ti chat transcript R3.pdf

over 5 years ago

0 Emrys Maier over 5 years ago

TI__Guru* 96712 points

Hi Steve and welcome to the forums!
I'm sorry to hear about the troubles you've had with TI's support. Fortunately you've ended up in the right place. The E2E forums are a bit different from your everyday forums on the internet -- here you can get help from other members of the community (some are extremely knowledgable), but what makes E2E unique is that there are engineers at TI (like me) that constantly monitor and respond to the forums -- we are required to get back to you in <24 hrs. I'm one of the three applications engineers that supports standard logic for TI, and I'll do everything I can to help you.

I want to be up front with you on what I know and what I don't. I'm not familiar with the 54C30, or even the 54C series of logic in general -- if you have a datasheet or a link to this device/family, it would be very helpful to me. I couldn't find anything. From your description so far, I understand that the 54C30 is an 8-input NAND with output on pin 8 and 3-V to 18-V supply.

TI only has one logic family that supports 3V to 18V, CD4k, which was acquired from Harris Semiconductor before I joined the company. The closest military rated match in CD4k would be the CD4012B-MIL, but that's a dual quad-input NAND gate, not exactly what you're asking for.

I found 8 devices that are both military rated and are of the '30 function (8-input NAND, pin 8 output), however none of them are from the CD4k family. Here's the list I found:

SN54F30
SN54AS30
SN54LS30
SN54ALS30A
SN5430
SN54S30
CD54HC30
CD54HCT30

If your application is in the 2V to 6V range, then you could switch to the CD54HC30, which is an 8-input NAND gate with the output on pin 8 (the '30 function is likely the same between the two families). The HCT version only works at ~5V and has lower input thresholds (TTL compatible), and the rest of the families are all bipolar, 4.5V to 5.5V.

0 Steve Mcgowan over 5 years ago in reply to Emrys Maier

Prodigy 20 points

The original part's datasheet is attached below.

The 5 vdc rail is supplied by an LM109 whose output voltage range is 4.6- 5.4 which would meet 2-6 vdc for vcc for the 54HC30.

This is a part replacement on in an existing design so I'm not sure anything but the 54HC30 would be an option.

I'd also had problems downloading which seems to have corrected itself.

Please let me know if you find anything else but voltage to check for compatibility.

National Semiconductor Datasheet MNMM54C30-X REV 1A0.pdfYou'd asked for the datasheet for the original.

0 Emrys Maier over 5 years ago in reply to Steve Mcgowan

TI__Guru* 96712 points

Hey Steve,
Thanks for the datasheet. It's interesting that this was an old National Semiconductor device but I don't have any records on it in my system -- I guess when TI absorbed National everything was paper based. That's the only explanation I can think of at least. One of my favorite professors in college (at UTA) was from National Semiconductor. I'll have to ask him what happened with the "C" logic family the next time I see him.

I know there have been some system updates over the holidays -- that might be the source of your download issues. I couldn't access this site for a couple days over the Christmas break.

*****

The SN54HC30 is pretty robust -- you won't see any problems functionally with that voltage range.

The SN54HC30 has input clamp diodes -- so you should make sure that the input voltage isn't higher than the supply as much as possible -- or if it is, know that there will be current flowing from the input up to the supply. From what I saw in the datasheet, I think the 54C part had these clamps also, but I'm not 100% sure.

It looks like the MM54C30 didn't have much drive strength (V_OH was rated at ~10uA), so it's possible that you might see over/undershoot from the much stronger drivers (~8mA) of the CD54HC30. Usually this doesn't cause any troubles, but it's something to be aware of if you're redesigning the system. Light loads (<15pF) on CMOS outputs tend to get some overshoot. Too much overshoot can activate the clamp diodes, but usually the overshoot is too fast for the diodes and nothing happens. I'd just try to keep that under 7V and above -1V.

The 54HC is _much_ faster than the 54C -- it looks like the typical delay was about 100ns for the 54C and the HC family is usually under 15ns. Again - probably not an issue, but something to be aware of in your system design.

Please let me know if there's anything else I can do to help.

Also - Happy New Year!

Logic

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I need to TI document explaining how to use and 54HC as a replacement for 54C