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TLV3501A-Q1: SHDN pin behavior

Alon Shemesh
Prodigy 10 points
Part Number: TLV3501A-Q1
Other Parts Discussed in Thread: TLV3501

Hi

while using this chip in one of our boards, we notice that the SHDN does not function as excepted. in order to be sure we designed a simple test board:

 

in this design pin 1 (IN-) connected to 3.3V via 10K resistor, pin 3 (IN+) connected to GND, pin 4 (VCC = 3.3V). 

pin 6 (SHDN) is connected to a micro-processor. this signal is toggled in a very low frequency. each time that the SHDN go's from HI to LO we see a pulse in the output (pin 5) although the 2 input pins are connected to DC:

Yellow: SHDN

Blue: output

do you have any explanation for this behavior?

how it can be avoided? 

attach the two fogures.

Thanks 

Alon Shemesh 

   

  • 0
    TI__Genius 11701 points

    Hi Alon, 

    thanks for reaching out. Our team is out on holiday today but we will take a look tomorrow to help you with your issue.

  • 0 in reply to Chi Nguyen1
    TI__Mastermind 24330 points

    Alon

    Thanks for your post. 

    It appears that our field apps engineer (Ziv Barak) who supports you posted your question on our internal version of the E2E forum.  

    Here is the response I provided him.

    Reviewing some testing that we have done here in our lab, I see a similar positive pulse at the comparator output shortly after bringing shutdown low (exiting shutdown mode).

    In regards to the datasheet, it would be good to state that the output of the comparator is not reliable within the first 100 to 150ns after coming out of a shutdown condition. Today’s datasheet only states that the output is high Z while in shutdown but doesn’t mention anything about recovering. The difference between setups, operating voltage, and process variation most likely explains the differences between the amount of time the output takes to recover. 

    Unfortunately this is how the tlv3501 behaves when recovering from shutdown and there is no known solution to avoid this from occurring.

    If you describe how they are using the comparator, maybe I can suggest a workaround but for sure it would require some external components.

    Chuck

  • 0 in reply to Chuck Sins
    TI__Genius 11701 points

    Hi Alon,

    We have not heard from you so I will be closing this post for now. Please feel free to reply again if you have any more questions or updates. Thank you.