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LM393B: Propagation Maximum Delay

Shinichi Inoue
Guru 20506 points
Part Number: LM393B
Other Parts Discussed in Thread: TLV1701, LM393LV

Dear Specialists,

My customer is considering LM393B and has a question.

I would be grateful if you could advise.

---

 I'm looking for a 1usmax propagation delay comparator. Cheaper is preffered.

(1) Regarding LM393B, could you please let me know the maximum value of the propagation delay?

(2) The TLV170x is tphl460ns/tplh560ns, can these meet 1μsmax?

(3) Could you recommend any other comparator?

---

I appreciate your great help in advance.

Best regards,

Shinichi

  • +1
    Guru 140200 points

    Hi Shinichi,

    as figures 6-4 and 6-5 of datasheet show, the actual response time considerably depends on the available input overdrive. And according to section 8.2.2.4 of datasheet the capacitive load and the chosen pull-up resistor at the output also play an important role. So, one would need to see the schematic and know more about the input signal to be able to say whether the LM393B can do the job or not.

    Kai

  • +1
    TI__Guru 53696 points

    Hello Shinichi,

    1. As Kai mentioned, response time is dominated by the amount of drive signal. Please see figures 6-30 through 6-35. As you can see, worst case would be a small overdrive at 5V at 125C.  Add another 30% for process variations.

    2. We do not have as much data on the TLV1701, but it seems similar to the LM393B in the higher overdrive area.

    3. What is the supply voltage and expected input signals? Other than cost, is there other specs important?

    If the supply voltage is 5V or less, see the LM393LV.

  • 0 in reply to Paul Grohe
    Guru 20506 points

    Hi Kai and Paul,

    Thank you for your reply.

    Propagation Delay increase 30% for process variation.　

    In other words, Maximum Propagation Delay is typical value plus 30%.

    I understand Propagation Delay is depended on overdrive voltage.

    When the overdrive voltage is increased, Response time is decreased.

    Also TLV170x, Maximum Propagation Delay is typical value plus 30%.

    It should show similar overdrive and response phenomenon.   

    I'll share these information with the customer.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi