L6472 stepper driver.
hello, we are using 4x L6472 driver chip on a single board for some time now. We used the internal 16MHz clock, but it appeared that the clock frequencies differ a lot from each other. According the specs it can be plus or minus 3%. With four motors running simultaneously, it looks a bit funny to see them running different speeds/s. So what we did is using an external clock source. This clock is generated by the attiny, so is only available after the tiny is up and running. This worked for a coupe of days.
now my question; this morning we blew up ( housing cracked open) 3 of the 4 L6470 while programming the Attiny. And we want to know why that happened? Also the boot diodes of three L6472 fried.
Is this because the L6472 needs a clock before it can handle the init strings via SPI? I cannot find anything in the spect about the external clock and/or/if it must be present before the L6472 receives serial data?
Or, is there an other reason why three drivers fry? where to look at?