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TL331-Q1: Quiescent current

Part Number: TL331-Q1
Other Parts Discussed in Thread: TL331, TLV1391, TLV7021, TLV7041-Q1, TLV1701-Q1, LMV7275-Q1, TLV7041, TLV9041

Hi, I plan to use TL331-Q1 for an automotive project. However, the datasheet in Section 6.7 says that the maximum quiescent current is 330 uA for V_S=5V, which is very high. Our customer requires the overall quiescent current be below 100 uA for the whole system. Could you please advise which TI analog comparator that is AEC qualified has a maximum quiescent current below 50 uA?



  • Hello John,

    Do you need a pin-to-pin equivalent? The TL331-Q1 has a unique pin-out that is not compatible with most other devices (note the reversed inputs), which would limit your choices.

    If you need a lower power version, there is the TLV1391, which is pin-out compatible to the TL331 and 80uA, but is not available in Q1.

    If you are able to change the layout, there are several possible devices.

    I would recommend the TLV7021 series at 10uA, but the Q1 version is not available yet.

    The lower-power brother, the TLV7041-Q1 is available, but is slightly slower due to the lower supply current.

    Other devices to review are the TLV1701-Q1 and LMV7275-Q1. But, again, these all have a different pin-out from the TL331-Q1.

  • Hi Paul,

    Thanks for your recommendation. I believe both TLV7021 and TLV7041 are good alternatives. It seems to me that the pin-out for TLV7021 and TLV7041 are identical for the SC70 package. Could you please confirm it?

    Could you please advise how to calculate the power loss (thermal dissipation during operation) of TLV7021/TLV7041/TL331 comparators? I would like to check the junction temperature based on the power loss and thermal resistance.



  • Hi John,

    The TLV7021 and TLV7041-Q1 (and Q1's) are in the same TLV70xx family, so the pinouts are the same across those devices, so theoretically, the TLV7021-Q1 could be dropped-in later if desired.

    The TL331 has a different pinout.

    Power dissipation would be the sum of the quiescent current, and the current dissipated by the output depending on load current.

    So for the quiescent current, use the max supply current and supply voltage. The max for the TLV9041 is 900nA:

     Pq = 900nA * 5V = 4.5uW (almost nothing as this is a nano power comparator)

    You need to know what current the output will be sinking, and the pull-up voltage. I'll assume 1mA using a 1k resistor and 5V pull-up.

     Iout = 5V/1k = 1mA

    Now you need to see what the voltage across the output is at 1mA, which is shown in the graph on Figure 6.17.

    So looking at the graph, at 1mA, the output voltage is about 90mV. So now calculate the output power dissipation:

     Pout = 1mA * 90mV = 90uW

    Then calculate the total power:

    Ptotal = 4.5uW + 90uW = 94.5uW

    So then you calculate the temperature rise using the Thermal Info (Table 6.4)  for the DCK package (@ 279°C/W):

     Trise = 94.5uW * 279 = 0.027°C

    Obviously, because this is a nano power device with very low currents and low voltages, the temperature rise is almost nothing. The TLV7021 would be a whopping 0.039°C!

    Remember that the die temp will be Trise + Tambient.

    A more detailed discussion of thermal calculations is available below. Though for line drivers, the concepts are the same.

     AN-805 Calculating Power Dissipation for Differential Line Drivers (Rev. B)

  • Hi Paul,

    Thank you very much for your quick reply and detailed explanation. I really appreciate it. This resolves my question.

    Best regards,