• State
  • Locked Locked
  • Replies 9 replies
  • Subscribers 63 subscribers
  • Views 1388 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV70033 Output voltage >1.5V with Enable pin pulled low

Jonathan Whitfield24
Prodigy 10 points
Other Parts Discussed in Thread: TLV700

We are using a TLV70033 to power peripheral devices on our device (SD Card, I2C peripherals, etc).  Our micro-controller is powered by a separate power supply (also a TLV70033) and is used to power down peripheral devices using the enable pin. 

When the enable pin is high (~3.3V) the regulator works fine.  When the enable pin is pulled low (0.0V) the output of the TLV70033 is between 1.4V and 1.6V.  The SD card requires a voltage of <.5V to hard cycle which we are now unable to do with the current configuration. 

With a 330Ohm resistor to GND on the output of the TLV70033 the output voltage drops to ~.45V when enabled is pulled low.  A 150Ohm resistor drops the output voltage to ~.25V.

Is there a minimum output load requirement for the TLV70033? I'm not particularly excited about having an resistor on the output of the regulator to fix this issue so any suggestions are welcome.


Thanks,

Jon

  • 0
    TI__Guru 55940 points

    Hi Jon,

    There is no minimum load requirement for the TLV700 family.  

    How much capacitance is on the output rail?  Does the voltage remain between 1.4 and 1.6V for an extended time or does it look like capacitors are discharging through leakage alone?  If it is a constant voltage, is it possible that something is biasing the output downstream from the LDO?

    One possible solution to the external pull-down resistor could be looking at a device with active pull-down.  For example TLV70233P.  

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Prodigy 50 points
    I don't know if I can continue here or I need to create a new Topic.

    I am using TLV70033 and when I send 0V to EN it draw ~30 uA anyway.
    But as soon as I connect 10K between EN and GND it goes down to what it should be, ~1uA.

    I am using a LiPo battery(3,8V) connected to Vin.

    Any idea?
  • 0 in reply to Daniel Nilsson
    TI__Guru 55940 points
    Hi Daniel,

    It is up to you if you want to continue or create a new topic. Some prefer to start a new topic rather than attach to an older thread, but it is not strictly required. In general we do prefer to limit threads to one device (TLV700 in this case) and one type of question (Ishdn in your case). This allows for more descriptive titles and helps when searching the forums for a similar question (as you would have done to find this older thread).

    When measuring ground current the setup can affect the measurement. It sounds like your power supply is drawing additional current when it is set to 0V. If you tie EN directly to GND without a power supply, do you read 1uA?

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Prodigy 50 points

    Hi Ryan

    Thanks for reply

    I have other stuff also connected not only TLV, I was measuring current directly after my battery, that supply all my stuff.

    If I remove Vin to TLV my stuff draws about 3 uA and when I put Vin back it draws about 35uA

    If I set my digital output(arduino)to zero that connects to EN it still draw 35uA.

    I don't understand how I can measure current if I remove power supply?

  • 0 in reply to Daniel Nilsson
    Prodigy 50 points

    Forgot, if I put 10k between EN and GND for one SEC it goes down to 1uA then I can remove 10k resistor.

    With power connected

    Can it be something with my output? Maybe I need to pull-up or pull-down?

  • 0 in reply to Daniel Nilsson
    TI__Guru 55940 points

    Hi Daniel,

    The specification that you are trying to measure is with Vin > 2 V and Ven < 0.4 V.  I apologize for not being clear, I did not mean to remove the Vin power supply.  If you directly short EN to GND instead of through your digital output, what current do you read?

    It is possible that your output or other circuitry is drawing the extra current; however, it is difficult for me to help debug without knowledge of your circuits.  Are you able to provide a schematic?

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Prodigy 50 points

    mysensorsboard_nocharge.pdf

    Hi

    I have attached a PDF of my hardware.

    I will measure what you asked for and get back.

    Please have a look at my drawing and comment.

    Thanks again

  • 0 in reply to Daniel Nilsson
    Prodigy 50 points

    I tried everything now, i think.
    With a diod between GND and EN, not working
    with a resistor between GND and EN, not working
    With a resistor between Vin and EN, not working
    With a resistor between Vin and EN, GND and EN, not working

    I think it is my Arduino that gives out some small volt to EN

    Thank you Ryan for your help and tips.

    I will live with these ~30uA even if I have to charge the battery once a year.
    You can close this issue or if you have found some errors in my drawing, please comment.

  • 0 in reply to Daniel Nilsson
    TI__Guru 55940 points
    Hi Daniel,

    Thank you for taking all of the measurements! I did not see any issues with your schematic. Best of luck with your application!

    Very Respectfully,
    Ryan