Voltage Level Shifters?

Mar 13, 2006 2 Replies
S

Hi all,



I have been asked to modify an existing design that is based on 5V parts. Several of the devices are older, and not available in 3.3V. The request is that I add IP addressibilty using one the Lantronix devices that the company uses elsewhere in their product line.



The Lantronix device I have to use is 3.3V, although it is 5V tolerant on the input side.



I am curious of there are preferred devices that I can use on the 3.3V lines out of the Lantronix part, to convert them to the 5V that the PIC requires, that won't cause timing or edge rate issues?



Thanks very much for any suggestions.



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J

Does the PIC require 5V TTL or 5V CMOS? Take a look at the Vih and Vil levels in the DC characteristics part of your PIC's data sheet. Most of the time, your 3.3V logic can drive 5V device inputs directly because TTL signals never were that high a voltage.

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Q

If your PIC can't handle 5V TTL levels as John suggests, you can use a

74HCT part to handle level translation from 3.3 to 5.0 V logic.
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