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INA203-Q1: INA203A-Q1 - delay specification

Josef Warta
Expert 4130 points
Part Number: INA203-Q1

Hello Team, following request:

We are using INA203AQPWRQ1 part and observed that without delay capacitor I am getting around 10-20µSec. delay at the output of CMP2.

Datasheet says CMP2 response time is of 1.3µSec. in my design from where this extra delay is generated this is what I would like to understand.

 

Another question is regarding comparator 2 delay time calculation formula shown below (taken from datasheet):


 

Does this mean that if I use 0.1uF capacitor then I will get 0.5 seconds delay at the output of CMP2?

Best Regards

Josef

  • 0
    TI__Mastermind 31545 points
    Hey Josef,

    The 1.3µs response time of comparator does not include the timing of internal 20x amplifier or the propagation delay time of the comparator itself. Response time of a comparator is essentially the rise time of its output from low to high. The propagation delay time is the essentially the overload recovery time of comparator output, where it is the time required for comparator output to start moving at all after the stat of VIN step. This is a standard measurement for comparators since their outputs are always in saturation (high/VS or low/GND).

    You need to make sure that you include what the response time of the internal 20x amplifier is and include this as a part of total response time. Additionally, the VOUT overdrive needs to be sufficiently high (>5mV) to meet the 1.3µs response/rise time.

    Do you get similar total response times when using Comparator 1? Unfortunately, I don't see any information about propagation delay for Comparator 2 when Cdelay is not populated.

    Sincerely,
    Peter Iliya
    Current Sensing Applications
  • 0 in reply to Peter Iliya
    TI__Mastermind 27715 points
    Hi Josef,

    It's been several days since your last post, so it seems like your issue has been resolved. If you need more help, please reply to re-open the thread or start a new thread with a new question. Thanks!

    Best regards,

    Ian Williams
    Applications Manager
    Current & Magnetic Sensing
  • 0 in reply to Ian Williams
    Prodigy 55 points

    Hello,

    I am actual user who have raised query to Mr. Josef. query is not resolved yet.

    i do not have answers for both the questions i asked.

    Regards,

    Nachiket W.

  • 0 in reply to nachiket wawoo
    TI__Mastermind 31545 points

    Hello Nachiket,

    We are very sorry that you’re questions have not been addressed. Let me clarify what I previously wrote and answer your questions.

    For your first question about why the total response time for comparator 2 is 10-20 microseconds instead of 1.3. The reason for this is because this is how the comparator 2 was designed and specified according to the datasheet. If there is no Cdelay, then the comparator 2 output response will be typical of the response seen in Figure 24, which shows a total response time of 11us. Keep in mind that Total Response time = propagation delay + Response Time.

    Additionally, the propagation delay for comparator 2 (10us typically) is much longer than propagation delay of comparator 1 (125ns typically) as seen with Figures 18, 19, 21, 22, 23, and 24.

    To answer your second question: yes, if Cdelay = 0.1uF, then total delay time is 0.5sec. This is directly a typical specification in current datasheet and complies with the Comparator 2 delay equation of Cdelay = to/5.

    Hope this helps you well.

    Sincerely,

    Peter Iliya