6733 glitches

[ampm]

Hello,

I have the following question about the 6733 analog output board:

Does it have channel-to-channel update glitches, what is their typical amplitude and duration?

I fail to find this information in the 6731/6733 specifications and on the NI web site.

Thanks in advance!

[samantham]

Hello,

Here are some links I think that you might have been looking for … I found the manual on the product page under the Resources tab. The Specifications list out the max update rates based on the number of channels.  I hope this helps.

NI PXI-6733

NI 6731/6733 Specifications

 

[samantham]

Hello,

I also think that this Knowledge Base will be helpful with the issue you are experiencing.  If not please describe the glitch issue and the application in further detail.

Why Does the Frequency Oscillate in the Output of My PCI-6733?

[ampm]

Thank you Samantha.

This is useful information.
Yet my question still remains. I'll try to put it in a different way.

Specifications for the 6722/6723 AO boards (http://www.ni.com/pdf/manuals/370822c.pdf) specify the value for the "Channel-to-channel update glitch":
Magnitude................................... 100 mV
Duration...................................... 1.2 μs
There is also a specification for the "Glitch energy (at mid-scale transition)":
Magnitude ...................................400 mV
Duration ......................................2 μs

I need the same information for the PXI 6733 AO board.
Can you please provide this information or give a link to it?

I currently do not have a 6733 device.

Thanks in advance.

[samantham]

Hello,

The NI 6733 does not have the same specifications as the NI 6722, since it does not have the same architecture.  The NI 6722/6723 has a latching structure, where all channels experience an update glitch regardless of whether its specific values is being changing.  The note in the 6722/6723 manual explains this as …

“Note Channel-to-channel update glitch is the energy glitch that occurs on all channels as the result of a channel update. For example, if you update the value of Channel 7, all other channels will experience this glitch regardless of whether their output voltages change.”

This is the reason why the NI 6731/6733 manual does not have a Channel-to-Channel Update Glitch magnitude and duration.  I am currently looking into getting you the Glitch Energy magnitude and duration for a signal channel.  I will post back with an update for the Glitch Energy.

[ampm]

Thanks Samantha!

Awaiting your information about the Glitch Energy magnitude and duration.

[samantham]

Hello,

Sorry for the delay.  After contacting R&D and looking into Digital to Analog Convertor (DAC) chip specifications, I hope that I found some useful information for you to use.  The DAC has a built-in deglitching circuitry.  The impulse for the DAC is less than 2 nV-s.  This implies that the area under the glitch is less than 2 nV-s.  Please refer to the attached image.  The image only shows a 1.36 pV-s glitch, however this should help explain the specification better.  Please note that specification is not the most common type of reference for glitches and is more than likely why we did not include it in the NI 6733 specification manual. 

NOTE:  This is not an official specification for National Instruments in reference to the NI 6733, however is a specification for the DAC used on the board.  We do not have comprehensive information on the card.  However, we expect the performance to be similar, but we cannot guarantee it.

Message Edited by samantham on 01-08-2008 01:40 PM

[ampm]

Thank you Samantha!

Questions:
1. Does the 2 nVs glitch impulse of the 6733's DAC correspond to the mid-scale transition?
2. What is the typical duration of the 6733's DAC glitch?
   2 nVs is an integral measure of the glitch and it would be helpful to break it into the "time" and "amplitude" components since the typical glitch time will give a clue to choosing
   parameters of a low-pass filter I need to build. Unfortunately I do not have a 6733 to perform these measurements myself; I just consider buying it...
3. Does the picture you posted show a 6733's DAC glitch for the 1LSB transition?
4. What does the "peak" glitch area mean?

Message Edited by ampm on 01-09-2008 09:10 AM

[samantham]

Hello,

1.       Yes, the 2 nVs glitch impulse of the 6733's DAC does correspond to the mid-scale transition.

2.       We do not specify have this information.  I can attempt to test it for you by pairing it with a digitizer.  I will see if the signal is not too small to read.  However, please note that this information could not be guaranteed if it was posted.  In addition, the value I could test would vary depending on factors such as transmission line effects.

3.       No, the picture is meant as an aid to better understand the specification.  The DAC currently used on the NI 6733 is a LT1597.  Please view the fully attached data sheet for your convenience. 

4.       The peak glitch area is equal to the area under the curve of the highest glitch impulse.  This is the integral of the signal over time.