Timing of ALE wrong

hal2003 · ‎2005-09-06

Posted on September 07, 2005 at 08:36

Timing of ALE wrong

hal2003 · ‎2005-09-06

Posted on September 07, 2005 at 08:04

Hi forum!

According to the datasheet of the ST10 the ALE high time is (4ns + t_A). I measured 36.7ns with ALECTL=0 and 49.9ns with ALECTL=1. This is far away from the promised 4ns. t_A=(49.9-36.7)ns=13.2ns this is close to the promised 12.5ns. The oscillator runs at 40MHz and direct drive is used. Has anyone of you an idea?

Thanks, Oliver

najoua · ‎2005-09-06

Posted on September 07, 2005 at 08:27

Hello,

No, this timing is not wrong but it corresponds to the minimum value that it could have, so the fact of having an ALE high time greater than 4ns is normal (the max value is not specified).

Regards,

hal2003 · ‎2005-09-06

Posted on September 07, 2005 at 08:36

Thanks for your fast answer.

I didn't expect the value to be that far away from the min. spec.

Now I figure it is the same with the time between WR# high to CS# high? The datasheet says it is (min) (10ns+t_F)=35ns and I just measured 350ns. This is 10x the given min spec!

Oliver