2021-08-29 09:59 PM
I recently purchased some secondhand ST M27C128B-12F1 online and am trying to program them correctly. The main information I am looking for is the Device ID, Vcc for writing and verifying (both), and Vpp. I was able to find a datasheet for the M27C128A but am not confident these parameters are the same.
Thank you!
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2021-09-01 11:17 AM
That's the code for the NMOS M27128A, the CMOS M27C128A was 0x20,0x0A
That wants 6.00V
2021-08-31 05:17 AM
Welcome, @EIcs.1, to the community!
The M27C128A was discontinued many, many years ago and there was never an M27C128B, you probably have a counterfeit device.
We can easily see more if you post a picture of it that is as detailed as possible?
Regards
/Peter
2021-08-31 09:31 AM
Thank you Peter. I uploaded a couple images to imgur of the EPROMs, I also bought some "M27C256B" which are pictured.
2021-08-31 10:12 AM
There seem to be contemporary profiles for these types of devices from SGS-THOMPSON / STMicroelectronics
Could be a die shrink, or second source agreement with about a dozen people making equivalent devices.
In any case you're so far beyond the sell-by date, it's probably unrealistic to get any type of support beyond that you can test/evaluate for yourself.
What's the Electronic ID report? You should be able to read it out via the programmer.
These should be 12.75V +/-0.25V programmed devices
2021-09-01 08:08 AM
It looks like the electronic ID is 20 89. Here's a screenshot of the profile I made in my programmer software.
I chose 13.00V for programming, 6.50V for Vdd Write, and 5.0V for Verify which was close to the specifications from the "A" device, see screenshot from datasheet. Does that seem right?
2021-09-01 11:17 AM
That's the code for the NMOS M27128A, the CMOS M27C128A was 0x20,0x0A
That wants 6.00V
2021-09-01 11:27 AM
Longer programming pulse, lower VCC
Overall the part seems slower, so it could well be someone got inventive and tested/binned the faster ones
2021-09-01 05:56 PM
Awesome sleuthing, Tesla DeLorean! I will try the settings appropriate for the NMOS M27128A and report back.
2021-09-01 10:19 PM
Thank you Tesla. I tried burning the EPROM with the settings for the M27128A and it worked perfectly. Also, now I better understand the value of knowing the device ID.