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TLV2242 quiescent current question

Ting Ye
Genius 11800 points
Other Parts Discussed in Thread: TLV2242

Dear Team,

I simulated TLV2242 1st channel as a buffer and 2nd channel IN+ tided to VCC and IN- tided to gnd in TINA and found the quiescent current is larger than spec ~uA scale.

May I know if this model is not suitable for supply current dc analysis or what causes the large currents?

TLV2242_IQ Question.TSC

Thank you!

Regards,

Ting

  • 0
    TI__Genius 9775 points
    Ting,

    The CMIR of the amplifier is 1 Volt below the Power Supply. By putting the "2IN+" into VCC, essentially you drive the second amplifier into saturation.

    Is there a reason you want to do it in that configuration? I would recommend that you put the "2IN+" in the middle of the input rail such as VCC/2 so that it is mid supply biased which is the normal operation of the amplifier, then you should be able to see normal current.

    Herman
  • 0 in reply to Herman Theodorus
    TI__Genius 11800 points

    Dear Herman,

    Thank you for the very prompt reply!

    But in TLV2242 ds, it shows input common mode range of 0 to VCC. http://www.ti.com/lit/ds/symlink/tlv2244.pdf

    May I know where I can see the CMIR 1V below VCC?

    The 2IN+ connects to VCC is from customer schematics. They thought it should be okay since TLV2242 ds says it is a RRI op amp.

    Buw will driving the 2nd op amp to saturation cause the about ~9A supply current in the simulation?

    Thank you!

    Regards,

    Ting

  • 0 in reply to Ting Ye
    TI__Genius 9775 points
    Ting,

    There is possibility we make a wrong assumption.

    Are you familiar with the device itself? I am extrapolating from the figure 1, 2 and 3. Usually one characteristic of CMIR is the offset starts to fall apart and if you see from the graph, it is about 1V below the power supply.

    However, it is possible that I made a wrong reading of the datasheet. Is the page 3 of the datasheet that says recommended operating condition, is this absolute max rating table? or is this actual CMIR of the device...

    Again I am not 100% certain from reading the datasheet, if you can confirm the actual operation of the device's CMIR and if you know it for sure, we can make the modification for the model.

    For temporary solution, you can also make modification on the model by descending into the netlist and modify the following lines:
    VIL NET016 VEE 0
    VIH VCC NET19 1

    into
    VIL NET016 VEE -0.01
    VIH VCC NET19 -0.01

    Again, let me know if you can confirm the actual CMIR of the device, we can make the modification and publish the revision on the web.

    Herman