27c322 bug ?

Rom1

Hi,
I have a T56 and some 27c322 are not programming correctly.

- The chips are fully erased, blank checked OK.
- Programming step goes well.
- Verify check tells me there is differences with binary image.

The same chip program OK on a Wellon VP280.
I also cross checked: programmed by VP280 are verified OK by T56; and programmed by T56 are both verified as ERROR on T56 and VP280.

I have another batch of 27c322 that is ok and program well on both.
Maybe a problem in settings or algorithm ?

Regards

admin

回复 1# Rom1

Please try to change Pulse Delay time  from 50us to 200us.
   

下载 (21.67 KB)

2021-5-8 08:14

or change VDD write: 6.25V->5.5V testing

Rom1

Thanks for your help.

I'll already tried changing pulse to 100us with no success.
Yesterday I pushed VDD write to 6.5v and every chip is programming right with only this change.


I'll give a try to both 200us and VDD 5.5v and keep you informed.

Rom1

Changing pulse time didn't work.
Reducing VDD was a success. How can you explain that both reducing and increasing VDD helps ?

Thanks a lot !

admin

回复 4# Rom1

The production date of this 27C series chip is relatively early, and the original factory seems to have stopped production, which may be related to the internal charging circuit of the chip during programming.