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AFE4490SPO2EVM circuit troubleshooting

Ranjith Kumbazha Omanakuttanpillai
Prodigy 190 points
Other Parts Discussed in Thread: AFE4490SPO2EVM, AFE4490

Hello,

We have prepared a PCB of AFE4490SPO2EVM as per the reference design in user guide for evaluation purpose.
Currently PCB hardware testing is going on without loading the actual firmware. Few test programs for testing the MSP430 Functionality were loaded and they worked . But didn't tested AFE4490 functionality in hardware or firmware means.

After populating components while we testing the voltages in the circuit it is found that the the output of the diodes D1, D2, D3 and D4 is showing as zero volt.

In my understanding the power circuit are working properly and the input to the diode are proper ie Rx_ANA_SUP (3 V) & LED_DRV_SUP(5 V) are coming between the  second and first (GND) pins of each diodes. But the voltage between the pin 3 of each diode to the and GND is showing as 0V.

While I measuring voltage at a EVM purchased from TI, it showing  voltages at 3 rd pins of D1 & D2 as 0.88 V and at  3 rd pins of D3 & D4 as 2.35 V. Only difference this board and our board is firmware is not loaded.

I  have checked after replacing  the diodes(So I think it is not the issue of diodes also all of the diodes showing same result) and after removing the jumper resistors R24(INM), R27 (INP), R44(TXM) & R48(TXP) lines  to isolate connection to the AFE4490 chip to the diode. But the results were same.

With these data can we assume any issue in our circuit? if so how can we trace it?

Please provide the normal voltage ranges needed to get at the 3 rd pins D1, D2, D3 and D4 pins in different conditions in normal connection and while isolated there connection to the corresponding pins AFE4490 ( ie removing jumper resistors R24, R27, R44, R47).

My assumption is that the issue happen due to AFE4490 chip side connection. Is any relation with these voltages with firmware?

Also, kindly request to provide suggestions for overall testing  and troubleshooting the AFE4490 related circuits of the AFE4490SPO2EVM board

  • 0
    Prodigy 190 points

    Hello

    Few more things about the above issue.

    I have tested the voltages in original AFE4490SPO2EVM board purchased from TI after removing

    jumper resistors R24, R27, R44, R47 then at TXM and TXP pins of AFE4490 chip shows voltage of 2.35, & at INM, INP 

     shows a voltage of 0.88 V. Also at  3 rd pin of D1 to D4 shows a voltage arount 0.7. But in our circuit these voltages are not getting. Anyway I think the issue in AFE4490 chip side. 

    My doubt is that, is it because the AFE4490 registers not set? 

    Please provide if have  test and troubleshooting information(like voltage range values in AFE4490 pins especially in INM, INPm TXM and TXP) which will help to test & troubleshoot AFE4490 hardware functioning.

    Also it will be helpful to me if provide details about  the purpose of D1, D2, D3, & D4 and voltage supplies given to them in AFE4490SPO2EVM sensor circuit

     

  • 0 in reply to Ranjith Kumbazha Omanakuttanpillai
    TI__Mastermind 18285 points

    Ranjith,


    We have received your post and hope to have a response back to you soon.

  • 0 in reply to Amy Schnoor
    TI__Mastermind 18285 points
    Ranjith,

    Can you try loading the default firmware? If you followed our EVM as a reference design, you can load the firmware. this will give you more details on what is wrong.