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Old February 25th 06, 07:20 PM posted to sci.electronics.design,comp.arch.fpga,rec.radio.amateur.homebrew
 
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Default Input stage for VHF frequency counter in an FPGA?

Hal Murray wrote:
http://www.onsemi.com/PowerSolutions...=MC100EPT21DR2


Be sure to check the output with a scope.

Years ago, I used a PECL=TTL part. That was real/old, 5V TTL.
The problem was that I really wanted a CMOS output and what I
got was a TTL signal that only went up to 4V or so. We had to
run it through an AC dead-bug to get what we wanted.


Good point to keep in mind. In this case though it's all 3.3v
families, and LVTTL seems to have nearly the same Vih/Vil spec as
LVCMOS. The part is spec'd with minimum Voh of 2.4v.