• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 34 subscribers
  • Views 419 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

questions about BBM of SN6501

Gilberto Igarashi
Prodigy 40 points
Other Parts Discussed in Thread: SN6501

Dear Sir,

I am testing a DC-to-DC converter using SN6501. The circuit adopted for testing was circuit proposed by Figure 67 of SN6501 datasheet (I am using Wurth 750313734, diode BYG20 instead of MBR0520L, and 5V for power supply).

Some questions appeared when I measured the D1 and D2 signals. I am sending attached a printscreen of my osciloscope.

Question 1:
According to Figures 59 and 60 of SN6501 datasheet (based on a power supply of 3.3V) the signal peak voltage is 3.3V. But, if you read the application information on page 16, it is informed that the peak voltage is equal to 2 x Vin, with regard to ground. What information is correct? In my printscreen was measured Vpeak=10V with power supply equal to 5V.

Question 2:
In my printscreen is not possible to see the break-before-make time between D1 and D2 signals. It is like D1 turn-off and D2 turn-on at the same time, not similar to the signal presented in Figure 59. Is this correct?

Regards,

  • 0
    TI__Mastermind 28265 points

    Gilberto,

    the reason for the difference between your scope shot and the and Figures 59 and 60 is, that your scope sheet is measured using a transformer, while Figures 59 and 60 are measured with the test circuit in Figure 2.

    The same is valid for the break-before-make time. This is only possible to measure with the test circuit in Figure 2, so with resistors instead of a transformer. When measuring with a transformer, the output that switches off keeps floating until the other output is fully switched on. So during the transitions, you really cannot measure a proper voltage with regards to ground because one output is already switched off (Break) while the other output is not switched on yet (Make). But you can see from this description that the Break occurs before the Make.

    I hope this clarifies it.

    Best regards, Thomas

  • 0 in reply to Thomas Kugelstadt
    Prodigy 40 points

    Hi Mr. Thomas,

    Thank you for the answer!

    Regards,

    Gilberto