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Original question:

CCS/EVM430-FR6047: Current Measurement

CCS/EVM430-FR6047: Current Measurement

Divya Harikumar
Expert 2020 points

Part Number: EVM430-FR6047

Tool/software: Code Composer Studio

Hi,

I measured the current consumption of the evaluation module with transducer attached(no external peripherals) running the default code (LPM-active) .

When i removed the jumper J32 and measured current across the pin i got around 7µA.

But when i measured line current i was getting around 91mA.

1) Isn't total power consumption linked to line current? 

2) Is the LPM ratings given in datasheet only for MCU excluding peripheral modules?

Regards,

Divya Harikumar

  • 0
    TI__Mastermind 47165 points
    Hello Divya,

    7uA sounds about right for the MCU current with transducers connected and LPM code running. This will vary depending on the configuration in the GUI as well. 91mA seems high for the total current. You may also be powering the eZ-FET and HID bridge circuit. You can disconnect this circuit by removing all J1, J2, and J3 jumpers after sending the configuration from the GUI.
  • 0 in reply to Eddie LaCost
    Expert 2020 points

    Hi Eddie,

    When i disconnected the circuit by removing all J1, J2 and J3 jumpers after sending the configuration from the GUI,i obtained total current consumption of 45mA(with transducer connected and default configuration).

    1)Isn't that value high??What might be the reason i am getting such a high current?

    2)What shall be the max.current consumption that i can expect?

    Regards,

    Divya Harikumar

  • 0 in reply to Divya Harikumar
    TI__Mastermind 47165 points

    Divya,

    When you say total current consumption, are you referring to the current shown on your power supply or something else? 

    The current that you measure across J32, this is the total current for everything on the MCU_VCC rail.  If you power the board at J33 and set the J32 jumper, You should see the same current as measuring across J32, but keep in mind that the current consumption shown on a power supply will not be very accurate in the micro amp range. 

     

  • 0 in reply to Eddie LaCost
    Expert 2020 points

    Eddie,

    I obtained total current consumption of 45mA(J1,J2 and J3 disconnected) when power was provided via USB line and current was measured using multimeter across J32

    When i provided external Vcc(3.3V) , i got an current consumption of 3.1mA (transducer disconnected) and 0.282 mA.(transducer connected) across J32.

    Are these values expected?

    Regards,

    Divya Harikumar

  • 0 in reply to Divya Harikumar
    TI__Mastermind 47165 points
    Divya,

    These measurements are higher than expected. I recommend using an external VCC and measuring across J32 or using a source meter. Is the meter that you are using fast enough to measure a fluctuating current such as the EVM? Be sure this is not measuring peak current as well. Also, do you have your measurements set to once per second? You should measure 10uA or less average current with measurements once per second.
  • 0 in reply to Eddie LaCost
    Expert 2020 points

    Eddie,

    Sorry for the delay in response.

    I measured the current across J32 and obtained 10uA when external Vcc of 3.3 V was supplied (POW_SEL switch set to the top position) along with USB connected and LCD being in OFF state

    The moment LCD was ON the average current increases to about 0.3mA.

    Is this expected?

    Regards,

    Divya Harikumar

  • 0 in reply to Divya Harikumar
    TI__Mastermind 47165 points

    Divya,

    Yes, this sounds about right depending on the configuration used.  The lowest power measurements shown in the TI Design are measured without the LCD on. 

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