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TLV521: Abs Diff Vin values

Antonio Faggio
Expert 8610 points

Part Number: TLV521
Other Parts Discussed in Thread: TLV7031

Hello,

My customer needs to know if the absolute value reported in the ds (300mV) (PAGE 2 PARAGRAPH 6) for Differential Input Voltage can be greater or not.

Customer realized that under certain conditions of use this value is exceeded, reaching 2V.

Many Thanks,

Antonio

  • 0
    TI__Expert 6625 points
    Hi Antonio,

    No, please ask your customer not to exceed the Abs max ratings as it may cause permanent damage to the device. TLV521 has input diodes hence exceeding the differential input voltage limit may permanently damage the diodes. In addition to this, other issues such as phase inversion, current leakage etc... may also occur when the device is operated outside its limits.

    Best Regards,
    Bala Ravi
  • 0 in reply to Bala Ravi
    Prodigy 50 points

    Hello mr. Ravi,
    do damages can be avoided by using resistors at both inputs of TLV521?

    If so, what are the minimum values ​​to use?

    Best regards,

    Francesco

  • 0 in reply to Francesco Abbruzzi
    TI__Expert 6625 points
    Hi Francesco,

    You can use resistors at the inputs to limit the input current BELOW 10mA. One more thing to consider is using this device frequently beyond ABS max rating could deteriorate the lifespan of the device. What application is your customer using this device for? Is your customer using this op-amp as a comparator, if so there are other op-amps without the input diodes that can be used for this application such as OPAx990.

    Best Regards,
    Bala Ravi
  • 0 in reply to Bala Ravi
    Prodigy 50 points

    Hi Mr. Ravi,

    thanks for your reply.

    This device is used as comparator.

    In one circuit, the maximum current is limited to 0.2mA and the differential voltage at inputs is 2.5V (transient). Typical values are current=0.09mA & Diff Voltage=1.7V

    In the second circuit the differential voltage at inputs exceedes maximum ratings for 70 seconds (at the startup once or twice a day) with max current =  2.5mA & the differential voltage at inputs equal to 4V(at 0sec) and 0.3V (70sec). Of course it is possible to reduce current value. After these 70 seconds absolutes values are no more exceeded.

    Best regards

    Francesco

  • 0 in reply to Francesco Abbruzzi
    Guru 140200 points
    Ciao Antonio,

    there are many pitfalls when using an OPAmp as comparator. For instance can the supply current dramatically increase when a non-vanishing differential voltage is given to the inputs. Another restriction is that the differential input voltage might be limited, as it is the case with the TLV521. If the manufacturer does not explicitely specify a maximum input current in the datasheet, then it's questionable whether a limiting of input current will help to prevent damage, at all. You would do this entirely on your own risk. I wouldn't do that.

    Why not using the TLV7031? This is a nanpower comparator.

    Kai
  • 0 in reply to kai klaas69
    Prodigy 50 points
    Hi Kai,
    thanks a lot for your answer.
    Unfortunately looking at data sheet I don't read the absolute value for Differential Input Voltage.
    Where can I see at this value?

    Best Regards,
    Francesco
  • 0 in reply to Francesco Abbruzzi
    Guru 140200 points
    Hi Francesco.

    there's no limitation of differential input voltage, as long as the input voltages do not violate the absolute maximum ratings (see section 6.1 of datasheet of TLV7301). Please also see section 7.4.1 of datasheet.

    Kai