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TPS706: TPS70618DRVR

sumeet pandit
Prodigy 20 points
Part Number: TPS706
Other Parts Discussed in Thread: TPS782

TPS70618DRVR is powered by 3.3V regulator(LDO) and the output is connected to VOC(volatile organic compounds) sensor IC which works on the minimum voltage of 1.68V and nominal voltage of 1.8V. the enable pin of the TPS70618DRVR is connected to output pin of the microcontroller(powered by 3.3V). but if we observe the voltage of the output of LDO and the Enable pin we found that there is a some glitch in the enable signal and the output of 1.8V (refer the below picture). the Problem we are facing is we are not able to read the VOC data which is powered by this 1.8V. This issue we are facing with the TPS70618DRVR part but with the TPS78218DRVT it works fine.

 CH1.--1.8V OUTPUT CH2:-ENABLE 

  • 0
    TI__Genius 12365 points

    Hello Sumeet, 

    Are all 4 images the same scenario? Also, is it possible to share the schematics of the circuit including how TPS706 is powered? Lastly, is there a way to apply a voltage to Ven without the Microcontroller?

    Best, 

    Edgar Acosta

  • 0 in reply to Edgar Acosta1
    Prodigy 20 points

    Hello Edgar,

    1. Yes, all the 4 images are of same scenario .
    2. Circuit reference is shown below. The LDO used is TPS70618DRVR AND 1.8V_LDO_OFF is the output pin of microcontroller. The VDD 1.8V is given to VOC sensor.

     

     

     

    3.Yes, applied the voltage to Ven pin there is not glitch observed , but what is the reason when we connect this to the microcontroller it shows the drop.

     

     

    Thanks,

    Sumeet P.

  • 0 in reply to sumeet pandit
    Prodigy 20 points

    Hello Edgar,

    Can you please update on  this.. is info provided sufficient or do you need more information on this??

  • 0 in reply to sumeet pandit
    TI__Genius 12365 points

    Hi Summeet, 

    I apologize for the delayed response I was OoO. 

    Thank you for sharing this information. 

    Is the MCU powered through the same rail as TPS706? 

    Is there a way to test the 3.3V from the MCU without the LDO? There is an internal pull up resistor between Vin and Ven, therefore, EN can be left floating and still enable the device: 

    I suspect it might be the current needed for the EN pin and/or the interaction of the MCU with the LDO:

     

    As for TPS782 the Ien is lower and does not have the same EN internal circuitry, therefore, the glitch does not exist. 

    Best, 

    Edgar Acosta