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TLV3011-EP: Input Clamping Diode Reverse Leakage Current

Pervaze Humayun
Prodigy 20 points
Part Number: TLV3011-EP
Other Parts Discussed in Thread: TLV3011

Hello,

We're using the TLV3011-EP comparator to track a nominal 28Vdc input to detect an Undervoltage condition. To reduce power draw and the effect of high-voltage transients, the R1/R2 divider is set at 100k/12.1k. There's also a hysteresis using a 604k resistor. Since this tracking is supposed to be highly accurate over temperature, I'm trying to factor in all the parameters that could affect it and come up with worst-case errors. One of the parameters that comes into play here is the 'Ir' of the ESD or Input pin clamping diodes about which no information is provided in the datasheet. Could you please share the Ir v/s Vr graphs at different temperatures for the internal clamping diodes of this comparator - the nominal and worst-case graphs would be helpful.

Thanks,

Pervaze Humayun.

  • 0
    TI__Genius 17125 points

    Hello Pervaze,

    Please see this post and let me know if you need additional information:

    e2e.ti.com/.../732845

  • 0 in reply to Kirby Kruckmeyer96848
    Prodigy 20 points
    Hello Kirby,

    Thanks for the link, that was partially helpful. What I'm looking for though, is the behavior of the input circuit, not when we have an over-voltage condition, but rather, when we don't. When the input is within the nominal range specified, how much do we leak to V+ and to V-? For instance, when you have a 1MOhm+100kOhm resistor divider for tracking an input, you only have uAs of current. If the input protection as well leaks current in that order, then it affects the accuracy of measurement, that's why it's important to me. In our design we need to guarantee trip voltages over a temperature range of -55C to +110C. So we need an accurate Worst-case analysis that factors in everything at play.

    Thanks,
    Pervaze.
  • 0 in reply to Pervaze Humayun
    TI__Genius 17125 points

    We do not have characterization data over temperature that would establish worst case, but you could estimate it.

    The typical input bias current of +/-10 pA listed in the datasheet is actually the worst case at +25C.  The typical at 25C is 1 pA.

    We know that since the TLV3011 is a CMOS comparator that the majority of the input current is associated with the input ESD protection diode and not the MOS transistor leakage. Thus, the input bias current should approximate the leakage of a reverse biased diode. Since that is the case we can use the approximation that the leakage, or bias current, approximately doubles for each 10°C increase in temperature above 25°C. Similarly, the leakage, or bias current, approximately halves for each 10°C decrease in temperature below 25°C. Since the maximum bias current is the concern the worst case should occur at 125°C.

     

    Based on the calculation that the current is doubling every 10°C the maximum input bias current at 125°C should be no larger than 10.24 nA. Using the same calculation for the “typical” current (1 pA @ 25°C) it should be about 1.024 nA at 125°C.