TMS320C5535: About the maximum current consumption of CVDDRTC

Hi O.H,

Thanks for reaching out on E2E with this question.  To directly answer your questions Q1 and Q2:  No, we do not specify any maximum or typical current consumption for CVDDRTC.

I understand that you are seeing slightly higher than expected current (76-120uA vs less than 75uA) on some devices.  Is there any additional failure associated with this higher current draw?  I.e. something is not functioning correctly on the device.  Or is the concern only related to the actual current?

Thanks,
Mike

Hi Mike,

Thank you for your supports.

No abnormalities other than the current value have been reported.

• Operation is as expected when powered on
• The difference in current waveforms is stable for the OK board, but a large number of spikes are seen for the NG board
• No problems have occurred after measures were taken to avoid using the LOT where the problem occurs

Best regards,
O.H

Hi O.H,

Thanks for confirming the current consumption is the only issue.  You mention there are current spikes for the NG board.  Can you elaborate on this, or show wave forms?  Ideally, I would like to see what the "nominal" current is, how frequently the spikes occur, the duration of the current spike, if there is any pattern to the repeatability or if the spikes seem to occur randomly.

One additional question:  If you swap the C5535 devices on a good and a bad board, (i.e. put the device from the good board on the bad board and put the device from the bad board on the good board), does the problem follow the board or the device?

Thanks,
Mike

Hi Mike,

Thank you for your reply.

Mike Pridgen said:

You mention there are current spikes for the NG board.  Can you elaborate on this, or show wave forms?  Ideally, I would like to see what the "nominal" current is, how frequently the spikes occur, the duration of the current spike, if there is any pattern to the repeatability or if the spikes seem to occur randomly.

I'm sending it to a private chat as the customer doesn't want to disclose it here.

Mike Pridgen said:

One additional question:  If you swap the C5535 devices on a good and a bad board, (i.e. put the device from the good board on the bad board and put the device from the bad board on the good board), does the problem follow the board or the device?

I'm asking the customer to do this.

Best regards,
O.H

Hi Mike,

Mike Pridgen said:

One additional question:  If you swap the C5535 devices on a good and a bad board, (i.e. put the device from the good board on the bad board and put the device from the bad board on the good board), does the problem follow the board or the device?

The customer did not perform a swap test (A-B-A cross checking).
The device is 12.1 mm square, with a ball size of φ0.4 mm, so they do not have an environment where they can immediately perform reballing.
However, based on the results of their investigation so far, the customer believes that they have obtained results equivalent to those of a swap test (A-B-A cross checking).

Best regards,
O.H

Hi O.H,

Thanks for sending the private chat.  I followed up there with some more specific questions about the customer's setup.  As long as we are discussing proprietary information, doing so over chat is fine.  Once we reach a conclusion, we can come back here to post a final update.

Thanks,
Mike