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AFE4300: Getting started with AFE4300

Ivan Rock
Intellectual 775 points
Part Number: AFE4300

Hello!

My question is related to basic configuration of AFE4300 pins to measure BCM. I use schematic based on TI Hand-to-Hand Body Composition Meter http://www.ti.com/tool/tida-00008

OUTP_Q_FILT.    <->.    OUTM_Q_FILT

OUTP_FILT.    <->.    OUTM_FILT

DAC_OUT     <->.    DAC_FILT_IN

MMT0..5     <->.    GND

IOUT0..5.    <->.    GND

 

Where should I use jumper and where not. As I said above I just need to measure BCM. And is my schematic correct?

2275.2318.AFE4300_BCM.pdf

  • 0
    TI__Genius 12555 points
    Hi,

    Please help me understand you query, are you asking why we need Jumpers between MMTx to GND ( Same thing from IOUTx to GND)?
    If thats your query then, you don,t need those jumpers.

    Going through the schematic I found that you have a AC coupling capacitor between INP1 and INPP1 ( same for INM1 and INMM1), this will be a problem as it will not pass the DC input to the signal chain and weight scale signal chain needs DC input.

    Regards,
    Prabin
  • 0 in reply to Prabin Yadav
    Intellectual 775 points
    Hi Prabin, thanks for your reply!
    I understood about MMTx to GND and IOUTx to GND.
    Am I right, that IOUT sends the sine wave through my body and MMT receives it to measure impedance? Each one has 6 channels (IOUT0..5, MMT0..5) how many channels do I need to measure body impedance, fat, water level, bone's weight, etc? All 6 channels? And how to attach them to the body, if I take IOUT1 in left hand and MMT1 in right hand will it work?

    And I'm about INP1 and INM1. I just need to measure BCM, not weight scale. Should I remove this coupling capacitors? For example, this schematic, which has to measure BCM also has decoupling capacitors on this lines www.ti.com/.../tidr117.pdf
  • 0 in reply to Ivan Rock
    TI__Genius 12555 points
    Hi Ivan ,

    Yes, you are correct. you need a pair of IOUTs to inject a sinusoidal current into the body and a pair of VSENSE/MMT pins to measure the voltage developed across the body. So at a given time you can have maximum of 3 pairs/channels .
    I am no expert in the biology , so I can't help you with the no of channels required for the BCM.
    Since you are not using Weight scale, you can leave the input pins for this signal chain floating.

    Regards,
    Prabin
  • 0 in reply to Prabin Yadav
    TI__Genius 12555 points
    Hi,

    I am closing the thread assuming you query was resolved. If you have any other issue please let us know.

    Regards,
    Prabin