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AM2634: 1.7v VPP generation

Shine
Genius 13655 points
Part Number: AM2634

Hello Champs,

Customer wants to enable the OTP Keywriter on AM2634-CC board. 

As it is mentioned in the AM263x_CC_E2_Modifications_rev1.pdf, the TP42 needs to be connected to GND, that is, TP42 is short to GND. 

Would you please confirm if it is correct to connect TP42 to GND?


Thanks
Regards
Shine

  • +1
    TI__Mastermind 22685 points

    Hi Shine,

    I'm not familiar with the AM263x_CC_E2_Modifications_rev1.pdf document.  If you can point me to where it is, I'll take a look and make any corrections as necessary.

    The intention of TP42 is to be able to be able to access the 1.7V VPP rail.  If U66 is populated, you can access the generated rail using TP42.  On the boards that do not have U66 populated, you can use TP42 to externally supply a 1.7V rail for VPP.

    I suspect from your questions that you are doing the second (trying to externally source VPP).  In this case, you will need to connect TP42 to the positive side of your external 1.7V supply, and TP41 to the negative supply.  You should NOT connect TP42 directly to ground.

    Thanks,
    Mike

  • +1
    TI__Mastermind 18470 points

    Hi Shine, 

    The problem is that we did not populate the U66 LDO circuit on the original builds of the board, but you still need to provide the 1.7V VPP for OTP operation. 

    My recommendation is to use a bench supply to provide the necessary 1.7V supply. You can do this by attaching the TP42 (VSYS_1V7) as the positive input and the TP31 (DGND) as the return. Hook these up to a bench supply and power the bench supply prior to running the OTP keywriter. 

    DO NOT SHORT TP42 TO GND. 

    Let me know if that is clear now. 

    Thank you,

    -Randy