On May 18, 2010, at 12:37 AM, Moreira, Luis A wrote: > I need to increase the sink capability from 13mA to around 20mA but > that is the max for the HEF4049. I looked around and the CD4049 can > sink up to 40mA which gives me sufficient headroom. > My question is do you see any reason why I can not just change it? I am surprised that there is so much difference in specs; I always thought that xxx40xx CMOS chips were pretty much compatible. That sort-of implies that even with a CD4049, you had better watch those datasheets pretty closely, and specify/test a particular set of vendors... I think "just changing it" is certainly worth a try; see how it behaves in the lab. Stacking is another option; I'm also surprised that the design doesn't already parallel gates for increased drive; I thought that was pretty standard for "driving" LEDs from 4000 series CMOS... BillW -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist