I am looking in way to detect presence of 20+ AC signals by rectification and multiplexing and taking them to 8 micro inputs. Few cycles delay in detecting is OK.
My first choice is to use RC filtering followed by tri state buffer. However, filter creates very slow edges or could be stuck between the levels for long time (hence need for Schmidt input). 74HC7540 from NXP looks as ideal part, but it is pricy and seems as single source. Does TI have cross reference or similar part (i.e octal tristate buffer with Schmidt Trigger inputs). Other solution is 74xx14 feeding the ‘regular’ buffer. It is 2 x cheaper, but more real estate is needed for additional componets.
Thanks,
Darko
