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CC1352R: Request the problem

SeokHO YU
Prodigy 50 points

Part Number: CC1352R

HI this is christ yu who is working at Hyundai company. I am developing device which is used CC1352 IC. I have one problem.

I use DIO_23 pin (It can use ADC )  as Battery monitoring funtion. I chose two resistor to divide Voltage to meet the guide of this pin ( ADC Input max 1.49V)

Before applying to  main voltage to CC1352R1 , VDDS Pins and other GPIO Pins are floating 0.6V and it makes problem on our system.

When disconnect ADC line ( ADC Line is connect Battery Volate to monitoring Battery Voltage) , This problem is disappear. I think that leakage current flow ADC Pin and it causes this problem.

How can i solve this problem? and I want to know it is normal condition or not.

  • 0
    TI__Guru**** 317180 points

    Note that the ADC input can be up to VDDS given that the input scaling is enabled. 

    What is the battery voltage? 

    From how you describe the issue it sounds like you are violating the Absolute Maximum Rating of the chip (See the datasheet). If I understand you description correctly, VDDS = 0 V and the voltage on DIO_23 is higher than 0 V which cause the ESD protection diodes to start conducting.

    Dependent on the available IOs you can include a switch (transistor) on the resistor ladder controlled by a DIO (turn the DIO on at startup) ensuring that DIO23 only get a voltage in when the chip is powered.  

  • 0 in reply to TER
    Prodigy 50 points

    Our device use Li-ion Battery (max 4.2V) and ADC pin is used for checking Battery Voltage.

     ADC input voltage range is 0~VDDS . So I use two resistors which is value 100k, 49.9k(1%) and make input voltage is (max) 4.2*49.9/(100+49.9) = 1.39V.

    Anyway the problem is caused by VDDS = 0V and DIO 23 = 1.39V ( Becuase Battery Voltage is Always on voltage). At that time ESD Proteciton diodes is conducting is right?

    And to solve the problem Should i add switch on ADC line to block always on Voltage(Battery voltage) ?

  • 0 in reply to SeokHO YU
    TI__Guru**** 317180 points

    "Anyway the problem is caused by VDDS = 0V and DIO 23 = 1.39V ( Becuase Battery Voltage is Always on voltage). At that time ESD Proteciton diodes is conducting is right?": Yes

    "And to solve the problem Should i add switch on ADC line to block always on Voltage(Battery voltage) ?": Yes