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AFE5816: After setting fixed programmable gain, my custom board power is shut down

Koo SeongWoo
Prodigy 120 points
Part Number: AFE5816

Hi, 

My custom board uses AFE5816 for ADC.

Referrring to AFE5816 datasheet, I set my AFE5816 register with the initialization set up 

This is my register setting sequence

0X01 - 0014

0X41 - 8000

0X42 - 8000

0X41 - 0000

0X42 - 0000

0X03 - 0010

0X00 - 0010 (for DTGC setup)

0XB5 - 00C0

0XB6 - 8820 (ERROR occurs)

When I set the B6 register with 8820 value, my custom board power is shut down.

Is there anything wrong with my register setting value or setting sequence??

Thank you 

  • 0
    Prodigy 120 points

    Additionaly, before settting register 1 , I gave 200ns hardware reset pulse to AFE 

  • 0
    TI__Expert 7565 points

    Hi ,

    1) What is the error you are seeing when you write 0XB6 register ?

    2) Are you giving any signal at the input of AFE while doing this ?

    3) Are the power supplies are deigned to give expected current for the AFE? 

    4) Are you following power supply sequencing as explained in datasheet ? If not followed AVDD_1P8 can have large current .

  • 0 in reply to Sachin H K
    Prodigy 120 points

    Hi, Thanks for response

    1) Setting the register to b6 precisely does not cause any issues, but putting 8820 into b6 causes abnormalities (no abnormalities occur when 8800 is put in). Also, putting 8800 into b6 and a value of 39 or higher into b5 causes abnormalities, in other words, giving an LNA gain code instead of an attenuator.

    2) Nothing in input during register setting

    3) I give more current than written in datasheet

    4) I'll check it and reply for it.

     

    I think contents I wrote in  1) is very weird. Is there anything suspicious?

  • 0 in reply to Koo SeongWoo
    Prodigy 120 points

    Hi,

    I checked power sequence. Actually AVDD_1P8 is applied to AFE little bit earlier before DVDD_1P2 ( about  100us). But In datasheet, After DVDD_1P2 reaches 1.2V, there is no problem.  Is there any problem after DVDD_1P2 reaches 1.2V? 

    Additionally, When I watch test patterns from AFE, There is no problem (I don't set DTGC register when i tried test pattern test)

  • 0 in reply to Koo SeongWoo
    TI__Expert 7565 points

    After supply is stabilized there is no issue as explained in datasheet. 

  • 0 in reply to Sachin H K
    Prodigy 120 points

    Then, is there anything else suspicious about register b6 & b5?

    1) Setting the register to b6 precisely does not cause any issues, but putting 8820 into b6 causes abnormalities (no abnormalities occur when 8800 is put in). Also, putting 8800 into b6 and a value of 39 or higher into b5 causes abnormalities, in other words, giving an LNA gain code instead of an attenuator.

    Are there any additional registers I need to set??

    As I wrote before, This is my current register setting sequence.

    0X01 - 0014

    0X41 - 8000

    0X42 - 8000

    0X41 - 0000

    0X42 - 0000

    0X03 - 0010

    0X00 - 0010 (for DTGC setup)

    0XB5 - 00C0

    0XB6 - 8820 (ERROR occurs)

  • +1 in reply to Koo SeongWoo
    TI__Expert 7565 points

    There is nothing wrong with register setting . 

    You can try the other modes in mode_sel register to evaluate this fixed gain. 

  • 0 in reply to Sachin H K
    TI__Expert 7565 points

    Is the issue resolved or do you have further query ?