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TPS73701 Quiescent Current

Tal Ben Porath
Intellectual 480 points
Other Parts Discussed in Thread: TPS737, LP8340

I would like to estimate the amount of current the TPS73701 LDO will "add" depending on the ourput current running through it.

I believe the common term for this is "Quiescent Current".

Unfortunately, I couldn't find any reference to this term in the data sheet.

My questions are as follows:

1. Is the meaning of the symbol I_GND (GND pin current) in the data sheet, equivalent to the "Quiescent Current"?

2. The data sheet states that when I_OUT=10mA, typically we'll get I_GND=400uA. What is the typical I_GND for I_OUT in the range of 0.5mA-1mA?

3. The above mentioned values appears in the data sheet under the assumptions that V_IN=V_OUT+1 and V_EN=2.2V. Will I_GND be significantly impacted if V_IN and V_EN are significantly higher?

Thanks in advance!

Tal Ben-Porath

  • 0
    Guru 140200 points
    Hi Tal Ben-Porath,

    yes, the GND pin current is the quiescent current of regulator.

    Have you seen figure 7 of datasheet?

    Kai
  • 0 in reply to kai klaas69
    TI__Guru 55940 points

    Hi Tal Ben-Porath,

    Quiescent Current (Iq) is a specific case of ground pin current (Ignd).  By strict definition Iq is a no load condition, as such we generally use the broader term Ignd in our datasheets.

    As  mentions, Figures 7 through 9 of the datasheet help show how Ignd will behave over various conditions.

    Very Respectfully,

    Ryan

  • 0 in reply to kai klaas69
    Intellectual 480 points
    Hey Kai,

    Thank you very much for the speedy answer!

    For some reason iv'e missed this figure and it is indeed exactly what I needed.

    Tal
  • 0 in reply to Ryan Eslinger
    Intellectual 480 points
    Hey Ryan,

    Thanks for the informative answers!

    It appears the GNS current of this LDO is too high for my needs.

    Does TI have a different LDO, which is pin compatible to TPS73701, has smaller GND current but can still support 1A output current?

    Thanks,
    Tal
  • 0 in reply to Tal Ben Porath
    TI__Guru 55940 points

    Hi Tal,

    TPS737 comes in multiple packages, as such I am unable to help with the pin to pin compatible requirement without more information.  The parametric search available at ti.com/ldo is a useful tool for helping to narrow our portfolio to your specific application requirements.  I have started a parametric search with the requirements you gave (1 A and low Iq) here.  As you can see from the parametric search LP8340 has the lowest typical Iq for an LDO with 1 A or greater that we have currently available.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Intellectual 480 points
    Hey Ryan,

    Thanks again!

    I'll continue searching for the optimal LDO.

    One last question regarding TPS73701: figure 7 depicts the GND current for 5V and 3.3V. I'm interested in the GND current for 3.6V-4.2V. Is there any way to get the appropriate graphs? If not, is there any way to estimate the behavior in this voltage range?

    Thanks again!
    Tal
  • 0 in reply to Tal Ben Porath
    TI__Guru 55940 points
    Hi Tal,

    The best way to estimate the behavior is to use Figure 7 to estimate. At Vin of 3.6 V you should be very similar to Vin of 3.3 V. At Vin of 4.2 V you should be approximately halfway between the 3.3 V and 5 V lines.

    Very Respectfully,
    Ryan