AD9517-4 Single-Ended Mode

anapoly on Jun 2, 2014

I have started using AD9517-4. Could anyone give me any advice as below?

On page4 in datasheet Rev.E, there is information about REFIN. I use only REF1 and I put 0.1uF at REF2.

So I use this device as single ended mode. I put 10MHz via 0.1uF DC cut into REF1. and VCP=VS=3.3V.

1. In this case, the mode is AC coupled, but the data sheet says the input frequency is 20M~250MHz.

Why does 10MHz REFIN work?

2. I have changed the input level from 0.6Vp-p to 3Vp-p. The device works properly in this all range.

It seems the REF1 port outputs DC. Though I put AC 10MHz the level is centered at +1.6V.

So it seems to meet all specification for DC and AC coupled for input sensitivity(except 10MHz frequency), which means that

10MHz swings 0.1V to 3V for DC coupled and 0.8Vp-p typ. for AC coupled.

Again let me ask why 10MHz with 0.6Vp-p work properly? If it is AC mode, it should work from 20MHz. I am cofused.

Best Regards

0 ADIApproved on Jun 5, 2014 4:34 PM over 6 years ago
Hi anapoly,

Our datasheet specifications take into account supply variation, temperature variation, and process variation. It is likely that you will find cases (for example, nominal supply and nominal temperature) where our part will behave fine but the configuration violates the datasheet limit. We do not recommend operating outside of the datasheet limits.

The same reasoning of number 1 above applies here as well. It is likely that the part is functioning correctly, we just cannot guarantee operation. The 0.8V typical number for input sensitivity is not a hard limit like the Max and Min input frequency. The thought here is that any standard 1.8V or 3.3V single ended LVCMOS signal applied to this single ended input will behave fine even if there is some board loss.

Regards,
Kyle
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0 anapoly on Jun 6, 2014 2:51 AM over 6 years ago

Thank you for your quick reply. Let me confirm your point.

1. In AC mode, I sould put frequency from 20 MHz (0.8V p-p typ.) not to violate datasheet, am I correct?

2, In DC mode, I can put 10MHz frequency provided that the swing level meets 0.8V max as logic low and 2.0V min as logic high and slew rate 50V/us min CMOS level, asm I correct?

Best Regards

anapoly
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0 ADIApproved on Jun 6, 2014 9:09 PM over 6 years ago

Hi anapoly,

Yes, you are correct on both of these.

Regards,
Kyle
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0 anapoly on Jun 8, 2014 6:04 PM over 6 years ago

Thank you. I am happy now. My control softwear seems to be working properly as well.

This case is closed.

anapoly.

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0 EZAdministrator

on Aug 2, 2018 2:40 PM over 2 years ago
This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

Thank you,
EZ Admin
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