• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 210 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS62080: Going into low power state when the pattern is mostly or all "1's"

Randhir Kalsi
Expert 4545 points
Part Number: TPS62080
Other Parts Discussed in Thread: TPS51206

Hello team,

Lately we have encountered some problems with the TPS62080 device that seem to be pattern dependent as it is used to generate 0.6V for VTT. Specifically it is my suspicion the device was going into low power state when the pattern is mostly or all "1's". We have a minor reowork to the board that adds a load on the output (~1.65ohm) to keep the device from going into low power state. We have been working the device very hard with this rework to see if it fails but it has been solid.

We are looking to TI to confirm our simulation in TINA is correct as well advise if adding this load resistance is a problem.

webench_design_1364399_127.TSC

  • 0
    TI__Guru*** 142710 points
    Hi Randhir,

    Do you have a waveform of Vin and Vout when it is not working right?

    The load probably just provides a current sink path for the DDR current. Normally, the Vtt rail must source and sink current. TPS62080 only sources current. The added resistor likely provides a path to sink current.

    An additional load like this is ok for the device, as long as the total load is within its rating.
  • 0 in reply to Chris Glaser
    Prodigy 10 points

    TEK00020.TIFHi Chris,

    Attached is a scope capture when the regulator was not operating properly. I did look at the input voltage to the regulator but did not take a scope capture as it was very clean.

    I still have an unanswered question regarding the device. Your statement the Vtt rail must sink and source current is correct. The TPS62080 device was chosen based on the fact the part integrates both a high-side FET (source current) and a low-side FET (sink current) per the data sheet. My unanswered question is since the part integrates a low-side FET why are we being told this device cannot sink current?

    Thank you,

    Randy Hare, iViea

  • 0 in reply to Randy Hare
    TI__Guru*** 142710 points
    Hi Randy,

    TPS62080 does not have a forced PWM mode feature. So, it always operates in power save mode, which does not sink current. This would be inefficient.

    The TPS51206 is typically used as a DDR terminator for the Vtt rail.