• State Resolved
  • Replies 11 replies
  • Answers 3 answers
  • Subscribers 62 subscribers
  • Views 197 views
  • Users 0 members are here
Support feedback
Options
Options
Related

TPS2H160-Q1: The current on eacn IN pin at INx=High with DIAG_EN=High

Yoshikazu Kawasaki
Intellectual 906 points
Part Number: TPS2H160-Q1


Tool/software:

Hello,

I have a question related to the thread shown below.  I looked through all the E2E thread, but they don't tell me the answer I need.

TPS2H160-Q1: Input current on IN pins - Power management forum - Power management - TI E2E support forums

My customer would like to connect capacitors on INx pins to maintain INx=High during their MCU becomes off unexpectedly like by the noise resetting the MCU.  Then they need the current consumption on INx pins to know the capacitor value.  Would you please tell me the current on INx pins at the conditions shown below?  The datasheet shows INx pins have internal pull down resistors of 175kOhm(typ), but my customer would like to know the other current that will be required from the condition of DIAG_EN=INx=High.

Vvs = 12V, DIAG_EN = INx = High, CS = open, Vcl = 0V, Voutx = 12V, Vther = 0V, Tj = 25degC

Best Regards,

Yoshikazu Kawasaki

  • +1
    TI__Expert 4030 points

    Hi Yoshikazu,

    the IN pins are digital pins and do not have much current draw, The pull down resistor is the only current draw on the IN pins so you can find the current on the pin by dividing the voltage of your MCU by the pull down resistor

    Best Regards,
    Nicholas Petersilge

  • 0 in reply to Nicholas Petersilge
    Intellectual 906 points

    Hello Nicholas-san,

    Thank you very much for your quick reply.

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    Intellectual 906 points

    Hello Nicholas-san,

    I got a reply from my customer.  They didn't get the expected result from the figure shown below.  The estimated resistor value was far from the one shown in the datasheet as 230kOhm(max) and it was around 2100kOhm.  Would it be expected?  If not, what would be the reason why they saw such high resistor?

    It took around 8.6 sec from 5V to 0.8V to discharge which gives R=t/C*In(V1/V0)=~2133kOhm.  It is far from the expected 230kOhm(max) anyway.

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Expert 4030 points

    Hi Yoshikazu,

    The 2133kOhm value is unexpected and I am unsure why you saw such a high number, Do you get the same measurement if you put a multimeter from enable to ground?

    Best Regards,
    Nicholas Petersilge

  • 0 in reply to Nicholas Petersilge
    Intellectual 906 points

    Hello Nicholas-san,

    Thank you very much for your support.  I met my customer today and discussed this issue.  The device itself works well as expected and even if they removed the capacitor, the resistor value didn't change much.  It's OL by using multimeter which means over limit as you know.  Could you please check if you also see Hi-Z with the same settings as theirs?  Is it possible to provide the equivalent circuit of IN pins?

    They'll check if it's also the same by replacing the device to another good one.  It should be the same since the current one works as expected as HS switch.

    Best regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Expert 4030 points

    Hi Yoshikazu,

    When I used a multimeter I got a pulldown resistance of 1.2M ohms however when I used a voltage divider with a 300k ohm resistor from a VS of 5V to EN, The voltage on EN was 3.1V meaning that the resistance of the pulldown would be about 500k.

    I also redid this with a 100k ohm resistor giving me 3.9V on EN which means that the pull down resistor was 350k ohms

    I did a final test changing the supply to 6V and then putting a 60k ohm resistor in series with the pull down and the voltage at VS was about 4.8V meaning that the pull down was around 250k ohms.

    So it seems that the pulldown resistance changes with the voltage on the enable pin and the spec in the data sheet is only when the pin is powered at 5V

    Best Regards,
    Nicholas Petersilge

  • 0 in reply to Nicholas Petersilge
    Intellectual 906 points

    Hello Nicholas-san,

    Thank you very much for measuring the resistance on EN pin.  I have a few questions.

    1. Did you use the setup like this?

    2. Would you please tell me why you used EN(=DIAG_EN?) instead of INx pins because my customer would like to know the resistance on those?

    3. Please let me go back to my original question.  Would you please tell me the expected current on INx pins with the conditions shown below?

    Vvs = 12V, DIAG_EN = INx = High, CS = open, Vcl = 0V, Voutx = 12V, Vther = 0V, Tj = 25degC

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Expert 4030 points

    Hi Yoshikazu,

    1. Yes the setup was like that except I was using the IN1 pin instead of DIAG_EN

    2. Sorry for the confusion, I was using the IN1 pin when doing my tests on other similar devices the same pin is called the EN pin

    3. it should be within the 230k ohm spec however it is slightly different from the datasheet as Vther is not 5V 

    Best Regards,
    Nicholas Petersilge

  • 0 in reply to Nicholas Petersilge
    Intellectual 906 points

    Hello Nicholas-san,

    Thank you very much for your quick reply.

    You said "it should be within the 230k ohm spec however it is slightly different from the datasheet as Vther is not 5V", but also did "So it seems that the pulldown resistance changes with the voltage on the enable pin and the spec in the data sheet is only when the pin is powered at 5V"  The setup on both you and my customer is the same.  The difference is the Vvs.  'd like to know the pull down resistance value at Vvs=12V or the expected current on INx pins.  Would you please tell me abut it?

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    Intellectual 906 points

    Hello Nicholas-san,

    I got additional information from the customer.  They checked 3 samples and all of those showed OL between INx and GND, so the pull down resistor shown in the datasheet as 230kOhm(max) isn't the one they need.  Please tell me the pull down resistor value at Vvs=12V or the expected current on INx pins.

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Expert 4030 points

    Hi Yoshikazu,

    You can't measure the resistance with a multimeter if the device is powered, you need to use a voltage divider on the enable pin and calculate how much resistance is on the enable pin. as INx is 5V in your application it should be 230k

    however this may not be useful as you are trying to hold the INx pin high for a certain amount of time and as the voltage drops the resistance on the INx pin changes.

    As it is not a spec in the data sheet I can't specify how the resistance will change over time to help you determine a capacitance for your application. It should be the same between devices so if you determine a capacitance that works  it should be consistent however I cannot guarantee it

    Best Regards,
    Nicholas Petersilge