Can you identify this part?

[eedesigner]

I need a little help identifying this chip. It is a 7-segment, 4-digit LED driver from a food smoker. I need to repair this board but I cannot identify the driver chip. The logo on the chip is the same logo silkscreened on the board, so I am pretty sure this part has a custom marking.

The 1447 marking is found on a variety of 7-segment driver chips, but none of them I’ve found are 20-pin devices with segment and digit pins laid out the way this device has them. I have looked at dozens of chips from TI, AMS, Maxim, and others. I cannot find ANYTHING out there that resembles this pin count and layout.

I have buzzed out the board and verified the most of the pin functionality as shown in the picture below. The pins labeled A through F and DP are the 7-segment and Decimal Point pins. The pins labeled D1 through D4 are the common anode driver pins for each of the four digits.

Any ideas?

[bob91343]

I can't really read it, too fuzzy.

[retiredfeline]

I think the 1447 is more likely to be a date or batch code. Maybe try to identify the logo? It's unclear in the photo.

[ataradov]

A quick search shows that this is a programmable MCU that is used in a lot of food processing devices.

There does not seem to be a way to read the firmware, so finding the chip will not help at all, unless you have the firmware and a programmer.

[eedesigner]

Sorry for the fuzz. Here is a better picture of the chip. I believe it has a custom marking since the logo is the same as what is on the board. I scrubbed the numbers pretty well, they don't show up anywhere that I could find. I was looking through sites like Mouser and DigiKey and sorting on 20-pin, 7-segment drivers trying to find an original part that has been re-branded. There are loads of chips that drive LED 7-seg displays, but none that I could find that are laid out in the same manner as this device.

It makes sense that it is a MCU, even though tons of parts are available to do what this does. It looks like it's time for the trash can. How did you find the MCU info? I looked all over for variations of the part number.

Thanks for your help!

[ataradov]

I just googled the part number and a few hardware fixers forums in Russian came up with the same device being mentioned. None of the threads have a solution.

It looks like this Made company is a contractor for a lot of food processor manufacturers. In that case their volumes must be astronomical, so it makes total sense to have a custom device.

Forums that mention the same IC: https://remont-aud.net/forum/58-94607-1 and http://monitor.espec.ws/section27/topic231404.html

[eedesigner]

Good find! I cannot read Russian, but can see that it mentions "TM3P945402-VO5 eeprom", and that's all I need to know.

Thanks again for the help!

[aqibi2000]

You can put a little 328p board in place of the eeprom once you’ve decided the 4 bit input/output

[ataradov]

EEPROM in that topic was in relation to an external EEPROM device that was connected to this MCU. It was used for storing the user settings, not firmware.

This can probably be replaced by another MCU, but you would have to reverse engineer the logic of the application. As usual with consumer electronics, it may not be worth  the time and effort.

[wraper]

But the elephant in the room is - does the fault really have anything to do with MCU? MCUs don't fail that often compared with other things, and rarely fail by themselves. You might be wasting your time on chasing red herring. TACT switches look weird. They are covered with some stuff. Often I see people on this forum halting their repair just because for some lame reason they just "need" to identify every chip on the board. No real repairman bothers with identifying some obscure chip unless there are significant reasons to suspect that fault is somewhere around it.

[eedesigner]

I don't really want to reverse engineer this too much or build additional hardware. A friend of mine sent me this board after I said suuure - I can take a look at that! I was looking for a data sheet on the chip to verify the power requirements and get pin descriptions. I was under the assumption before that the driver chip was dumb like all the others. I was wanting to read a spec sheet, hook up a SPI or I2C port to it, and work with it using my own MCU on a SBW debug port. That is obviously not going to happen.

Thanks for the help!