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2N7001T: 2n7001T power consumption

Peter Chen(ICP_FAE)
Intellectual 2480 points
Part Number: 2N7001T
Other Parts Discussed in Thread: SN74LVC1G11

customer reported 2N7001T heat issue.

their user scenario is 

VCCA=3.3V, VCCB is 1.8V and 2N7001T input is always "high".. 

According to datasheet, the power consumption in 2N7001T s close to 50mA*1.8 and 50mA*3.3V, based on the power consumption, the 2N7001T will has heat problem.

Can you look at the application again?

  • 0
    TI__Guru* 96752 points

    Hi Peter,

    Where did you get 50mA for the static supply current of the 2N7001T?!

    Here's the Electrical Characteristics table of this device -- ie where you should be looking:

    And I've highlighted the maximum static supply current for each supply. So your calculation should be 8uA * 1.8V + 8uA * 3.3V = 40.8 uW

     

    If this answers your question, please click the "this resolved my issue" button; or reply and I will continue to help.

  • 0
    TI__Intellectual 2210 points

    Hi Emrys,

     If this is true, the IC temp. should be ambient temp.,not hot. 40.8uW * 463 (C/W) = 0.02 C. Is it necessary to add resistor to limit current? Or any wrong connection on this cicuit?

  • 0 in reply to Alan Chang
    TI__Guru* 96752 points

    Hi Alan,
    I'm assuming that the SN74LVC1G11 is operating at 1.8V?  Three's no listed supply on the schematic.

    If the purpose is to down-translate from 3.3V to 1.8V, then I don't see any problems. Also, I can't see what CSS_HEALTH is up to -- hopefully that's a clean square wave signal that's never left floating.

  • 0 in reply to Emrys Maier
    TI__Intellectual 2480 points
    Hi Emrys,
    there are 2 things i would like to mentioned.
    1) 50mA is the absolute value. 8uA is correct one.
    2) customer mentioned in their application when VCCA=3.3V, VCCB is 1.8V and 2N7001T input is always "high". the IC temp (or should be ambient temp) is hot. according to package information: 40.8uW * 463 (C/W) = 0.02 C. Is it necessary to add resistor to limit current on VCCA/VCCB path? Or any wrong connection on this circuitry as Alan mention?
  • 0 in reply to Peter Chen(ICP_FAE)
    TI__Guru* 96752 points
    Hi Peter,
    Are you saying that the device is getting hot, or that you're worried that it will get hot?

    I've already stated that I don't see any problem with the above circuit, and that the device should not have more than 8uA of static current. Is there more I can do to help?
  • 0 in reply to Emrys Maier
    TI__Intellectual 2480 points
    Hi Emrys,
    No t worried 2N7001T will get hot and customer reported the 2N7001T is getting hot base on their schematics above.
    any thoughts?
  • 0 in reply to Peter Chen(ICP_FAE)
    TI__Guru* 96752 points
    Hi Peter,
    If the customer is seeing a temperature rise in the device, I would need to see the input and output signals in an oscilloscope shot to help troubleshoot. The schematic above doesn't tell me much.

    It's most likely that there is a short to Vcc or ground at the output of the device if they are seeing extreme temperature issues -- I can't think of any other reason this device would get hot. The device in static mode will use very little current.

    If they have checked this and can only find the 2N7001T at fault, I would recommend starting an FA with their supplier so we can get the parts here to be tested.
  • 0 in reply to Emrys Maier
    TI__Guru* 96752 points
    Hi Peter,
    I haven't heard back from you in a while - I'm goign to go ahead and mark this thread as "resolved" and close it. If you need further assistance, please respond here -- or if you have found a solution, I would love to hear about that as well.