• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 38 subscribers
  • Views 407 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.

LM5007 Datasheet Calculation Differs from Simple Switcher Calculation

Bruce White32
Prodigy 110 points
Other Parts Discussed in Thread: LM5007

I used the LM5007 datasheet (Page 5, Equation 2)  to calculate the value of Ron for a switching frequency of 1MHz. With a Vout of 6V and an Ron of 40.2k, I get a result of 1.05MHz.

I then used the 40.2k Ron value in a Simple Switcher simulation with a 100mA load. In the resulting design document, in the "Operating Values" section, it states that my switching frequency is 800kHz.

Which one is correct?

  • 0
    TI__Intellectual 2360 points

    Hi Bruce,

    The LM5007 operating value for frequency currently has an issue with not updating when you change Ron. We are working to address this. However, if you run a steady-state simulation, the frequency can be calculated based on the switching period shown. For the example you provided, the steady-state simulation showed a switching frequency of 985kHz, which is reasonably close to the estimated calculated value based on the datasheet equation.