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CC2541: Current consumption inquiry for CC2541

daniel su
Intellectual 505 points
Part Number: CC2541

Hi Sir,

We got a power consumption issue when using CC2541 . Following are the detail description.

   

  

(1) Use 2 power supply on the circuit. One is fixed 3.3V that is applied to VCC_3V3. Another one is variable 2.0V~3.0V that is applied to BAT (one end of R2).

(2)When 3.3V power supply is tuned “ON” and BAT is applied to 3.0V as well. CC2541 will do initialization to configure P0.6&P0.7 as input 3-state and going to low power mode.

(3)Tune BAT voltage from 3.0V to 2.0V, and record the VCC_3V3 current consumption as following file.

The result shows the VCC_3V3 current consumption will increase significant when BAT voltage down to 2.0V. Can help to investigate and explain? Thanks.

  • 0
    TI__Guru** 106705 points
    Hi Daniel,

    You are pulling the input voltage of P0_6 and 7 to a mid-rail voltage. This will cause the input buffer to start conducting current. The closer to mid-rail you get, the higher the current will be.

    If you want to measure a voltage with the ADC you must configure the pins as analog inputs.


    Cheers,
    Fredrik
  • 0 in reply to Fredrik K
    Intellectual 505 points
    Hi Fredrik，

    Thanks for your answer. We just want to avoid continuous(quiescent current) power consumption during the ADC channel for battery level is idle. According to your explanation, We must accept this quiescent current because it's far smaller than the conducting current.
  • 0 in reply to daniel su
    Intellectual 505 points

    Hi Fredrik

    When we configure P0.7 as output "Low" and P0.6 as "ADC" input permanently, the VCC_3V3 current consumption becomes three times higher than normal condition when BAT voltage is 3.0V.

    The full test result is attached for your info. Please explain and advice how to configure these two I/Os (P0.6&P0.7) to avoid such higher current consumption. 

    Thanks and Best Regards

    Daniel Su

  • 0 in reply to daniel su
    TI__Guru** 106705 points
    Hi Daniel,

    When configuring P0_7 as output low you will continuously conduct current through the resistors. With 300kohm the current will be 10 uA at 3 V.

    You must remove R3 so that Vbat is connected directly to P0_6. You should probably also change R2 to 0 ohm.

    Cheers,
    Fredrik