TPS659037: AM5746 PMIC

Jongeun,

Can you verify that you have TPS6590379 samples and not TPS6590378 samples?

There are two versions of this device, and SMPS9 is disabled in the TPS6590378 version.

The top side marking should say OTP 97, not 96.

I think the schematic should be okay for SMPS9. One note on reviewing the schematic, is that GPIO_7 (POWERHOLD) is pulled up to VRTC. This is the pin that enables/disables the device. In this setup, the device cannot be disabled without removing power, which means the power down sequence for the processor cannot occur.

Thanks,

Nastasha

Thank you Nastasha.

The OTP version is 0x97.

I checked wave form on SMPS9 with scope.

sequence is )   0V ==> 1.8V ==> about 4mSec later ==> 0V with slope(during 8mSec)

I thinks It seems that protection function is activated by short-circuit protection.

And I suspect that 3.3V power and 1.8V power are short together at some-place.

So I disassemble the parts that powered by SMPS3(3.3V).

example) disassemble the Phy1 and check SMPS9 power, disassemble the phy2 and check SMPS9 ouutpu again.

Finnaly all part is disassembled and there is only AM5746 on my board.

but the SMPS9 is still death.

So There are some question.

1) Please check this schemetic.(Power interface to AM5746)

    I attach the schemetic.request1.pdf

2) This is EVM's schemetic. I did not apply this part on my design.

    Is this related to my problem?

   Let me know that tihis function is necessary or optional?

Thank you in advance.

Hi,

The circuit on the left is making sure that VIO_IN of the PMIC is supplied after VCC1. We recommend supplying VIO after VCCA, though this should not be related to the SMPS9 behavior. A few questions:

1. Does this behavior happen on multiple boards?

2. Do you have i2c access? if so can you read the INT_STATUS registers to check for any faults?

3. Can you probe the INT pin?

4. Can you share the scope shot of SMPS9 that you took with the output voltage and the SMPS9_SW pin signals?

Thanks,

Nastasha

Most of all. Thank you for reply.

< Following is answer for your question >

1. Does this behavior happen on multiple boards?

      Yes, all of board has same behavior on SMPS9.

     We made 5 sample board.

2. Do you have i2c access? if so can you read the INT_STATUS registers to check for any faults?

   As you know the SMPS9 supply the V3_3V for I/O power for CPU, so we can not connect to CPU via JTAG. And can't access to PMIC via I2C.

3. Can you probe the INT pin?

  Not, yet. After probe I will upload the capture image.

4. Can you share the scope shot of SMPS9 that you took with the output voltage and the SMPS9_SW pin signals?

< Following is my question after several experiment >

1. I check the current on V3.3 line with modified circuit.

    But power-on seqeuence is ignored.

    The current is over 1.1A.

    the CPU make a burnt smell of a circuit.

    I think this situation make PMIC activates the short-circuit protection on SMPS9, Is this right?

2. I suspect following situation.

    Is this situation possible?

 3. Is there any other reason to make this situation?

Thanks,

Jong-Eun Kim

Jong-Eun Kim,

Yes, this looks to point to a short circuit behavior. Can you verify that the rail stays on with the resistor depopulated?

Thanks,

Nastasha