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TPS3701: Does not work

Gary Poon
Intellectual 510 points
Part Number: TPS3701

I purchased some TPS3701DDCR from Arrow. When I test the IC I got very strange result. The resistors I used is: R1 = 1Mohm, R2 = 22Kohm, R3 = 30.9K ohm. The two output OUTA and OUTB are pulled high to 3.3V.

I expected the UV is around 8V and OV is around 13.6V.

However when I test it the output never change even I change the monitor voltage to a rather low voltage. The output is always high.

When apply 12V to the monitor voltage and check the INA voltage, it is around 10.94V, and the INB voltage is around 0.335V. is it correct?

Is the "dot" on the marking represent the pin1?

Thank you.

  • 0
    TI__Genius 12630 points
    Gary,

    The "dot" represents pin 1.

    Your calculations are correct and you should be set for Vmon(OV) = 13.629V and Vmon(UV) = 7.96V.

    It sounds like the device could be damaged. The INA and INB pins should never exceed the recommended operating conditions of 6.5V at these pins which when monitoring 12V, the resistors should be dividing the voltage down so that 6.5V or less appears at the INA and INB pins at all times.

    I have just a couple questions to help me understand more of the circuit.

    1) What is the VDD voltage? What are the pull-up resistor values?

    2) Have you tried multiple devices? Have you used known-to-be-working devices?

    I will try to get this figured out as quick as possible.

    -Michael
  • 0 in reply to Michael_DeSando
    Intellectual 510 points

    1) What is the VDD voltage? What are the pull-up resistor values?

    VDD: 3,3V

    pull-up resistor: 10K ohm

    2) Have you tried multiple devices? Have you used known-to-be-working devices?

    Yes, tested for two IC.

    I test the IC independently on a breadboard. Just supply 12V and 3.3V at two output of a DC power supply.

  • 0 in reply to Gary Poon
    TI__Genius 12630 points
    Gary,

    We have not seen this before with the output stuck logic high no matter the input voltage. Could there be an issue with the connection from OUTA / OUT B to the pull-up resistor? Are you using two separate pull-up resistors or a single pull-up resistor with the outputs tied together?

    Do you have a schematic you can provide?

    The output should be low at around 0V up until Vmon reaches around 8V but you are seeing the output high even when Vmon is removed?

    It appears to be either a bad connection or damaged devices. I would like to know if the circuit has ever worked for any devices?

    -Michael
  • 0 in reply to Michael_DeSando
    TI__Genius 12630 points
    Gary,

    Is there any new information related to the possibility of a bad connection or damaged device? Please let me know if this item requires more support. Thanks.

    -Michael