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Can NI6509/NI6509e receive LVTTL signals



I'm using the NI6509 and NI 6509e.  According to the specifications, the minimum input voltage is 2V. 


Does it mean, I can input a LVTTL signal (3.3V) ?

Is it recommended to use it like that?  The alternative is to use a circuit to convert LVTTL to TTL, but, obviously, I'll be happy not to do it if not necessary.




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You should be able to use the LVTTL signal directly as 3.3V is above the 2V minimum that is required to register as a logic high for an input.


Best Regards,

John Passiak
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Hello Rafi,


I believe you shouldn't have any issues with using the NI-6509 to read a LVTTL signal. Just to be clear though, our device will not read a Logical high value until the voltage is above 2 Vs. I believe that since you have about 1.3Vs of clearance from this threshold you shouldn't run into any issues.


If you do notice issues with this, converting this to a TTL would be a good solution as well.

Jim St
National Instruments
RF Product Support Engineer
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