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LVTTL Digital output on the 9402 is giving 2V pulses

I'm setting up my new cRIO system which consists of cRIO-9064 with NI 9402 digital IO and NI9264 AO. 


My problem is with the NI 9402. My application consists of reading input pulses and giving output pulses (delay generator). I chose this module for its high-speed performance. The input pulses (TTL) are being read fine, however the output pulses (LVTTL from the 9402) are not being picked up by the target equipment (switch). The switch requires a TTL input (50ohm). I have tested with a signal generator that a 3V pulse is sufficient to trigger the switch, so I would have thought that LVTTL would drive this switch fine.


Checking with an OSC the pulses from the 9402 are 1.98V peak to peak (50uhm impedence setting), which seems a bit on the low side for LVTTL. 


Is there a way to tweak the voltage level of the 9402 digital outputs? (easiest solution but I doubt it's possible)


Otherwise, do you have a recommended chip (or even better integrated solution) that can convert the LVTTL signal to TTL?

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The following link provides a good graphic for TTL and LVTTL voltage ranges:


'CMOS and LVTTL Voltage Levels'


The minum for the high output voltage is 2 V and the maximum for the low output voltage is 0.4 V, yielding a worst case 1.6 V p-p signal.


To drive a TTL switch, I would recommend a TTL digital output module.



~ Q ~

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