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LM7310: regarding 1.2us response time

Premalatha Royappan
Intellectual 910 points
Part Number: LM7310
Other Parts Discussed in Thread: TPS22965,

Hi

This is regarding the response time(1.2us) of LM7310 ,which we are using in our design for over voltage protection.

In our design,the output of the LM7310 is provided to AM6254 through a power switch(TPS22965DSGR). We have set the threshold of the LM7310 circuit to 3.52V as we want to cut of voltage beyond the recommended voltage of AM62xx(3.135V - 3.465V). There is a chance by which 5V can be fed to LM7310 by mistake, during which the LM7310 should switch off the output. We understand from the datasheet that response time is 1.2us. So would there be any spike in the output voltage of LM7310 after which it would be cut off? Kindly let us know if this response time is ok for our design particularly for AM625x.The below is our implementation. The output from LM7310 is supplied to a Power switch and PMIC which supplies power to AM625x.

  • 0
    TI__Guru* 79071 points

    Hi Premalatha,

    Thanks for reaching out. Within the response time VOUT will follow VIN.  So if your input is very high slew rate such that it can peak in 1us then VOUT will follow that peak. But I don't think it will be a problem because output of efuse goes into input of TPS22965 which has abs max rating of 6V so 5V transient should not be a problem.

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Intellectual 910 points

    Hi

    The accidental 5V is from TPS54561DPRR as per the below circuit. We want to know under the possible fault use-case scenario (i.e. 5Vdc being fed instead of 3.3V to LM7310) – that no damage  happens to AM625x.The output of LM7310 is connected to the processor pins through the power switch. The processor supply pins are rated for 3.3V.Hence kindly confirm on this as we don't want the processor pins to get damaged. please consider the slew rate of 5V buck and also the response time of Power Switch.

  • 0 in reply to Premalatha Royappan
    TI__Guru* 79071 points

    Hi Premlatha,

    I don't know whether your processor can handle 5V for 1us. But yes eFuse will take 1us to respond within which VOUT will follow VIN, I can only confirm this thing. Generally all our eFuse will have this much response time.  If it is possible you can try evaluating using LM73100EVM.

    Regards

    Kunal Goel