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AFE4490 power optimialization

Other Parts Discussed in Thread: AFE4490, MSP430F5529

Hey all!

I have a question that is related to the power of AFE4490,
I have developed the pulse oximetry using arduino pro mini 3.3V and 8MHz clock speed, with AFE4490 and NJL5501r photodiode
it was able to record the ADC average, 
However it does not stays longer, the red light and the IR light slowly faded.
and i am suspecting that this caused by power management. 
So, i am just wondering what i need to consider for the power of AFE4490 without blowing up anything?

Best Regards, 

Stella

  • Stella,

    1. When do you begin noticing this issue? 
    2. What are the LED currents?
    3. Can you measure the AFE supply currents? Are there excessive leakage currents?
    4. Is this issue reproducible?
    5. Can you read the AFE registers after the issue occurs?

    It would help to troubleshoot, if you can provide more insight to the problem.

    If the AFE supply currents are with the specs from the datasheet for your test conditions, then you should be fine.

  • Hey, Praveen,

    This is issue happened once i connected the AFE4490 (it is actually AFE4490 EVM that i modified by blocking its communication with MSP430F5529 chip so it communicates with arduino instead of MSP chip) with the arduino. 

    I checked on the scope, it is able to send the writing register

    and i checked on my arduino interface and scope, that it is able to read from the LED too, 

    But it stays briefly, the LED faded soon. 

    I'm just thinking perhaps that because the power that give from arduino and AFE4490 is colliding, 

    since i powered my arduino through USB wire to PC, while at the same time, I also powered my AFE4490 with its USB wire too to PC. So, it looked like this 

    I am suspecting that my mistake is that i am only blocking the ADC reading on the MSP430 without blocking power supply on it (Which the power should rely on power from arduino itself)?
    Perhaps do you find this uncanny too?

    Stella

  • Hi Stella,

    This looks to be the same project as your other posts. I believe my answer to the other post may solve this issue. If not let me know. Also, could you put all questions in regards to the same post in the same thread to minimize confusion?

    Thanks,

    Gui