TLV9032: Max Toggle Frequency for Push-Pull Output?

Hi Vince,

this also depends on your input overdrive voltage and the capacitive load. See figures 6.15 to 6.22 of datasheet. So please specify your input overdrive voltage and the capacitive load.

Kai

Kai,

Thank you for your support as always!

Hi Vince,

Thank you for your post. I think Kai pointed out some important aspects of your design that will affect propagation delay and rise/fall times of the output. Once you provide the load capacitance and the overdrive on the inputs, that will give us a better idea of the potential speed of the output.

Best Regards,

Joe

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Thank you both Kai and Joe.  Please assume 100mV overdrive with 20pF max load for now.  I sort of expected that you might be able to tell me what TI saw based on actual test data for the parts, and the relevant test conditions (like the data sheet did for the open drain version of the part), rather than trying to infer or extrapolate the behavior from that data for other conditions. If you can share that information, that may be fine as well.  That's why I didn't specify those variables in my original question.

Hi Vince,

doing interpolations and extrapolations with the help of shown data and figures in the datasheet is the deeper sense of publishing a datasheet. It's impossible to publish data for all sets of parameters because this would mean an infinite number of specifications and figures.

So, doing interpolatins and extrapolations is not a crutch but the highly intended way to use a datasheet

From figures 6-15 and 6-16 you see that the rise and fall times are not differing relevantly between 15pF and 20pF. And from figures 6-17, 6-19, 6-21 and figures 6-18, 6-20, 6-22 you see that the propagation delay times are differing only marginally at 100mV input overdrive voltage.

Kai

Hello Kai,
     I am not sure that one can always determine reliably the max toggle rate directly from output fall times and propagation delays alone.  As an example see "http://dspace.mit.edu/bitstream/handle/1721.1/16854/51585845-MIT.pdf;sequence=2" Section 3 "Toggle Rate Limitations." 

So, as you see, from the perspective of a user with only the datasheet to work from, an actual toggle rate test is a more holistic test, considering the sum of all the variables involved in the comparator, and provide confirmation that there is not another undocumented variable or behavior, that might affect the products performance in such a scenario.

In asking my question, I was hoping that since a Toggle Rate performance metric was published test for the open drain version, that similar direct data was was acquired for the push-pull version that would provide that additional assurance.  From the nature of your response, it would appear that either such data is not available, or that from what you see internally in your test data, you are suggesting that the above terms are the only variables necessary to provide a complete picture of the Toggle rate performance.

Hello Vince,

Let me take a look to see if we have this data and get back to you by the end of business next this upcoming Monday.

Best Regards,

Joe

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi Vince,

you may find this thread useful:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1081821/tlv7041-unable-to-output-high-level-voltage

Kai

Vince

Thanks for your patience on this post.  One little clarification on the toggle frequency line in the d/s, it is actually for both the open drain and push pull device.  When we tested with the open drain device, the pullup value is 2.5k.  In regards to everyone's inputs so far, there is much truth in all the comments.  However, while each parameter such as trise, tfall and prop delay all play a part and provide some guidance, the only true way to know the overall toggle frequency is to measure it.  

Now to try and answer your question, looking at simulation and char data, I can see variation down to 2.5MHz due to process, voltage and temperature variation.  Unfortunately, this is right at your required limit, so I don't think I would recommend TLV9032 for your application.  Our next best option which would meet your needs would be our TLV3202 which is approximately 2.5x faster.  Their is no specific line in the datasheet for toggle frequency but from design simulation and targets of 10MHz, your 2.5MHz is well within and would not be expected to have a problem.

Chuck

Thank you Everyone for the great information.  This is what I was concerned might be the case.

Chuck,
     If I might ask, what behavior could we see if we bump up against the toggle rate limitation?  Would it be pulses that will just have a minimum on or off time, or might there be some other interesting behavior such as premature output reset, when the input differential pulse is somewhat shorter than the toggle rate limitation?

Thank you,

-Vince