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tas5706evm

james foryst
Prodigy 10 points
Other Parts Discussed in Thread: TAS5708, TAS5713

I am trying to understand why ti did certain things in there evm design linked here
http://focus.ti.com/general/docs/lit...0&fileType=pdf

1) Like i don't understand why the common mode resistors are 4.7kohm, I use R9=R10=R11=R12 = 1/(√2 • 2πfCC1) this formula i got off this page Understanding output filters for Class-D amplifiers | Audio DesignLine
in which case it is much lower for this design more like 3-6ohms, depending on fc. Can someone explain the rational 4.7kohms? Thanks

  • 0
    TI__Guru**** 189399 points

    Hi, James,

    The 4.7kohm resistors are in there to discharge C33-C36. If I recall correctly, we were worried about them having charge on them when the amp was re-started, and that would cause a pop. By adding the resistors, we insure the caps are kept discharged when the amp isn't driving them.

    They are only needed if you're using it in single-ended mode with C33-36.

    Check out TAS5708, they aren't in there.

    It's always best to use our newest parts, they offer the best in price/performance trade-off. Check out my personal favorite part, the TAS5713. It runs cool as a cucumber!

    -d2