DM9368N woes

[smb...@gmail.com]

Going out on a limb here, I have a project that I chose to use DM9368N 7-segment LED drivers on. This is a nifty driver that takes 4 bits and produces a hex digit, 0-F, on the 7 segment display. It even does this with built-in current limiting so no external resistors are needed.

I bought 5 of them in 2017, only to see every one of them has a different random problem. They're clearly genuine ICs, because they "mostly work", with various problems such as a single segment not lighting or the latch input being stuck on, or other random issues.

I bought another 15 of them this month, and every single one of them has exactly the same problem. They don't latch data. I've even fussed with them manually by applying my own inputs with jumper wires.

I do have a total of 4 of them that are known-good, from other sources, so I know my circuit itself is not an issue. Sergey's XI8088 also uses them, and I get the same broken behavior there.

So now I'm looking for some place that I can trust. Anyone got a source?

Scott

[Mike Loewen]

I've had good luck with Unicorn Electronics in PA:

https://www.unicornelectronics.com/prod.htm

They list the 9368 for $14.99. They have a $30 minimum order, but you need
at least three, you're covered.


Mike Loewen mlo...@cpumagic.scol.pa.us
Old Technology http://q7.neurotica.com/Oldtech/

[Scott Baker]

Ouch! I designed my board to take 10 of them because ... well ... they cost about a buck each on aliexpress.  $149.99 for display drivers is probably not something I can justify. :(

It's cheaper to remanufacture the board and go with TIL311 displays at about $3 each, and it saves on board space. Smaller display though.

Scott

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[smb...@gmail.com]

Now starts the interesting process of getting a refund from aliexpress for the defective ICs.

Last night, I submitted a refund request that the ICs were damaged with photographic evidence that they do not work. They changed my "damaged" claim to "does not work" and replied that "does not work" is not a valid reason for refund.

The order was less than $25, so it's not a big deal, but if receiving defective merchandise is not grounds for return/refund, then I'm tempted to suspend all purchasing through aliexpress. There's too much junk sold from these vendors in China.

Scott

[Lee Hart]

Alas, buying from China entails the risk of "getting oats that have already been through the horse". The 9368 is a rare part, so the price is high which can encourage fraud.

If you haven't laid out the PCB yet, another possibility is the Motorola MC14495. It's a CMOS version of the 9368. I bought some on ebay from Hifiic and they were all good. The 9368 is an old TTL part, and runs flaming hot; like 100mA per digit! The CMOS version in comparison barely gets warm.

Another possibility is to program a PAL/GAL/PROM etc. to do the same job.

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/3a6dba79-38da-4289-993d-f2893a908274n%40googlegroups.com.

[smb...@gmail.com]

Lee, this looks like a great idea. I have already built the board, in both DM9368 and TIL311 versions, but I'll add a MC14495P version as well. The TIL311 displays also get crazy hot. It would be nice to have something that generated less heat and used less electricity.

With 10 DM9368 (or 10 TIL311) I feel like I could heat my office with the thing.

Scott