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TLV8544: EMIRR Questions

Ting Ye
Genius 11800 points
Part Number: TLV8544

Hello Team,

There are questions regarding TLV8544 EMIRR performance. Could you help provide comments?

1. In TLV8544 datasheet Figure 25 EMIRR performance, is the measurement done by injecting noise at input pin via conduction method?

2. In TLV8544 datasheet Figure 25 EMIRR performance, the frequency response is from 10MHz to 1000MHz. Could you provide a reference EMIRR freq response up to 6GHz?

3. In AN-1698 Figure 7, it shows EMIRR frequency for IN+, IN-, VDD, VSS. May I know if you could provide the same test methods for TLV8544?

Regards,

Ting

  • 0
    Guru 140200 points
    Hi Ting,

    the best way to handle EMI is to shield and filter...

    Kai
  • 0 in reply to kai klaas69
    TI__Mastermind 23425 points

    Hey Ting

    Thanks for reaching out on the TLV8544.  Answer to your first question is yes.  Figure 25 is EMIRR from driving the input directly.  I will need to get back to you on your other questions and see how high a frequency our new test setup can drive. 

    In regards to testing on power pins and output, I will review our test hardware and see if that is possible.  The application note you referred to had a dedicated hardware constructed for that testing.  In order to test to those frequencies, it requires a dedicated piece of hardware.

    I saw Kai's comments regarding how to handle EMI.  I agree that shielding is always a nice idea, shielding alone does not solve EMI problems.  Conducted EMI comes in directly on the wires that enter a shielded box.  Using shielded wire like coax limits the amount of pickup but having low value shunt capacitors to ground at each entry point on the board is very effective.  Many engineers are two eager to drop 0.1uF capacitors down for all de-coupling but in the case of high frequency EMI rejection, I suggest using ceramic capacitors in the 10pF range.  The same is true for decoupling power supply pins in systems with high levels of radiation.  It is generally recommended to use 3 capacitors for proper supply bypassing to cover different frequency ranges.  Usually we recommend capacitors in the 10uF, 0.1uF, and nF or pF range.

    I will get back to you on the testing capability after I speak with our validation team.

    Chuck

  • 0
    TI__Mastermind 49906 points

    Hi Ting,

    1. The tests apply the signal directly to the pins from the generator, as shown in AN-1698.

    2. The graphs shown are for the inputs - which tend to be the most vulnerable.

    3. Our setup only goes to 4GHz....Past 3GHz, the results really depend more on the layout and bypass caps than the device itself.

  • 0 in reply to Paul Grohe
    TI__Mastermind 23425 points
    Ting
    I am going to close this post but if you need to continue this discussion, feel free to reopen or contact us.
    Chuck
  • 0 in reply to Chuck Sins
    TI__Genius 11800 points
    Hi Chuck,

    Okay. I will let you know if I have further questions.