Hi,
More than a matter of personal taste avoiding a resistive divider using a
active circuit you could benefit from its low output impedance. With a
resistive divider there could be some issues in terms of impedance matching
when a load it is present but as been said it all depends on how good that
level translation should be.
Regards,
Vasco Soares
----- Original Message -----
From: "Hal Murray" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Cc: <[email protected]>
Sent: Wednesday, October 01, 2014 4:10 AM
Subject: Re: [time-nuts] Clock level conversion 5V -> 3.3V
[email protected] said:
I would suggest some 3.3V logic (inverter) gate with 5V tolerant inputs
from Little Logic TI portfolio. There are buffered and unbuffered gate
available.
What's the advantage of a chip over a pair of resistors?
[email protected] said:
I have seen a resistive divider used in a similar application, but
wondered
if I could save the couple dozen mA they were spending.
Power might be one. If it's a long enough run that you need a
termination,
then the power doesn't cost anything extra. If it's only a few inches,
you
can use higher values of resistance to save the power.
For a given value of resistance and a specific chip, there should be some
crossover frequency where the power of the chip matches the power of the
resistors. It might be fun to play with the numbers.
--
These are my opinions. I hate spam.
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