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TPS7A90: LDO as a load switch

Prudhvi Sagar
Genius 3785 points
Part Number: TPS7A90

Hello,

My application has a sensor which requires regulated voltage for precise measurement, also requires it to be low-powered so I need to turn off the sensor when not in use. I have seen that Iq and I shutdown are low for LDO. Can I use it as a load switch as well?

Regards,

Prudhvi Sagar

  • 0
    Guru 140200 points
    Hi Prudhvi,

    yes, this should work.

    Which sensor are you planning to use?

    Kai
  • 0 in reply to kai klaas69
    Genius 3785 points
    Hello Kai,
    I am planning use the sensors fromMaxbotix. www.maxbotix.com/.../MB7334.htm.

    Regards,
    Prudhvi Sagar
  • 0 in reply to Prudhvi Sagar
    Guru 140200 points
    Hi Prudhvi,

    this should work.

    Kai
  • 0 in reply to kai klaas69
    TI__Guru 55940 points
    Hi Prudhvi,

    Are you intending to use TPS7A90 as an LDO or a Load Switch? From your statements it sounds like you are intending to use the TPS7A90 as an LDO in order to regulate the output voltage and that you simply need to enable/disable the LDO in your application. A load switch is a different type of application (you can read more about load switches here: www.ti.com/.../slva652.pdf ). Do you need a load switch or is the enable function of the LDO enough to satisfy your application requirements?

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Genius 3785 points
    Hello,
    Thank you for the support. Leakage current (2.3) is not an issue as TPS7A90 also has low Q, shutdown and ground current. I need to check slew rate (2.4) and power down rate (2.5). Other than these can there be any more issues?

    Regards,
    Prudhvi Sagar
  • 0
    TI__Mastermind 45830 points

    HI Prudhvi,

    As long as VOUT is set higher than VIN, the LDO will operate as a switch. The TPS7A90 is a good choice, I think you may want to look at the TPS7A35 as well.

    Regards,

  • 0 in reply to JCHK
    Genius 3785 points

    Hello, 

    If Vout is set higher than Vin LDO will not work right? TO turn OFF the LDO I can directly use EN pin right?

    Regards,

    Prudhvi Sagar

  • 0 in reply to Prudhvi Sagar
    Guru 140200 points
    Hi everybody,

    I think there's a bit confusion about the term "load switch". Prudhvi has a sensor which he wants to turn-on by just applying a supply voltage. And he wants to turn-off the sensor by ramping down this supply voltage. That's why he wants to use a voltage regulator with an output enable.

    Kai
  • 0 in reply to kai klaas69
    Genius 3785 points
    Hello,
    I am slightly confused now whether to use it or not :(.

    Mu requirements:
    I need my sensor to get regulated voltage.
    I need to turn it off using a GPIO pin
    I need the device to consume less power when turn off


    Regards,
    Prudhvi Sagar
  • 0 in reply to Prudhvi Sagar
    Guru 140200 points
    Hi Prudhvi,

    I see no problems. I give you a "go".

    Kai
  • 0 in reply to kai klaas69
    TI__Guru 55940 points

    Hi Prudhvi,

    Thank you for confirming that you are using TPS7A90 as an LDO rather than a load switch.  You can drive the EN pin of the TPS7A90 with your GPIO.  When Ven is logic high, the LDO will regulate the voltage for your sensor.  When Ven is logic low, the TPS7A90 will consume 0.1 uA typically (15 uA max) and the output rail will be discharged through the active discharge resistance of 250 Ohm.

    Very Respectfully,

    Ryan