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TLV 3012 Input question

Dan Skrabacz
Prodigy 20 points

Supply Voltage + = +3.3 Volts

Supply Voltage - = 0 (Ground)

Utilizing the 1.24 Volts reference in my comparator application.

My customer is placing +5 Volts on the IN+ for 1.5 millisecond duration (pulse). They put the pulse on there every few minutes or so when they run a test. They've done this 50 times on several units.

The data sheet for this device specifically states that the common mode input voltage is Vs + 0.2.

The comparator was working fine with this type of input, then all of a sudden (after about the 50th time), my customer was getting a strange output on the UUT.

Question: What is the failure mechanism of this device when too much voltage is placed on the IN+ terminal in the comparator configuration?

  • 0
    TI__Genius 12375 points

    Dan,

    This test has most likely damaged the internal ESD protection structures on the inputs of the comparator. The customer's test is exceeding the absolute maximum specifications for the part:

    The ESD structures can be thought of as diodes to the supply rails. Placing a resistor in series with the inputs of the comparator can limit the current which flows into the inputs of the part when the ESD diode has been forward biased, potentially preventing damage.  

  • 0 in reply to John Caldwell
    Prodigy 20 points

    John,

    If the comparator is damaged (meaning that it has been stressed beyond its limits), will the comparator output a 0 or a 3.3 volts if I continue to apply supply voltage of 3.3 volts?

     

     

  • 0 in reply to Dan Skrabacz
    TI__Genius 12375 points

    It would depend on how that particular comparator has been damaged, which can be extremely variable from unit-to-unit even under the same conditions.