• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 64 subscribers
  • Views 3522 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.

TPS62110 Data Sheet Question

Antenna_Head
Genius 11745 points
Other Parts Discussed in Thread: TPS62112, TPS62111, TPS62110

Team-

When reviewing the TPS62112 converter with a customer today, they expressed some concern over the startup transient.

Specifically, Figure 14 of the TPS62111 data sheet has several traces labeled CH1, CH2, CH3, and CH4, all having to do with startup and soft start, but there isn't a legend that tells us what each channel represents.

Can you please review/clarify this portion of the data sheet so we can make a better recommendation to the customer?

Best regards,

Steven Dunbar, AFA Colorado

 

  • 0
    TI__Guru 68716 points

    This info will be forwarded to the product line so that the data sheet can be updated.

     

    Figure 14—Start-Up Timing

    CH1—Enable

    CH2—Vout

    CH3—Input Current

    CH4—Inductor Current

     

    Figure 13—Output Ripple

    CH1—Output Ripple Voltage

    CH2—Switch Node

    CH4—Inductor Current

     

  • 0 in reply to Bill Johns
    TI__Expert 4490 points

    Please elaborate on the answer in light of the soft start description contained in the DS.

    1. Trace 3 and 4 are confusing. Trace 3 looks more like I would have expected the inductor ripple current to look like.

    2. If trace 3 is input current (per answer above), then why is there significant input current initially and a constant output voltage (~0.4v)? Where is the input power going?

    3. There is an apparent discrepancy between the magnitudes of the two current waveforms. The peak input current should be the same as the peak inductor current.

    4. Please verify that the scale for CH3 is 500mA/div (not 5V/div as labeled).

    5. Was this test run with an active load set to constant current? It doesn't look like what I would have expected with a resistive load, which would have been a better load for this curve.

  • 0 in reply to Mark Pieper
    TI__Mastermind 35115 points

    Mark,

    The scales for Trace 3 and 4 are in fact switched.  CH3 is the inductor current with 500 mA/div.  I was not able to recreate the exact waveform on CH4 but it is similar to what I observed at the SW pin.  I will post a reply when I can confirm what is shown by CH4.  You are also correct that it is done with an active load set to constant current.  The attached powerpoint includes my measured startup into both an active load and resistive load.  These were taken with the TPS62110 on its EVM.

    If you have any additional questions I'm happy to answer them for you.

    Anthony