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TL5209: the ESR of Cout

Comi Li
Expert 3150 points
Part Number: TL5209
Other Parts Discussed in Thread: TPS7A26, TLV767

Hi team,

I have two questions on the application of TL5209. In the datasheet, it points out that the ESR of output CAP should not approximately equal to 1 ohm on page 14.

Question 1：

I’m not sure if the cap at the end of the load is included in the output cap. Or does it just mean the ESR of Cout?

Question 2：

The datasheet just states that ESR cannot be equal to 1 ohm. Are there any other constraints on ESR? For example, max and min values?
Why can't ESR be 1 ohm in this case, and what is the value range of ESR related to?

By the way, the TL5209 seems to be a very old device, do you have a recommendation for a more suitable replaceable device?

Thanks for your support.

Comi

  • 0
    TI__Expert 5231 points

    Hi Comi,

    Thank you for bringing up this question. We have put your device in a tool that we use to compare other devices and we would suggest either the TPS7A26 or the TLV767. I have attached an image of the comparison between the two packages. Please note that these devices do not come in the same package as the SOIC, which is the package that you are currently looking at. If you have a packaging constraint and must use the SOIC then I can find out more information regarding the ESR of COUT. 

    Have a great day. 

    Thank you,
    Josh Nachassi 

     

  • 0 in reply to Josh Nachassi
    TI__Expert 3150 points

    Hi Josh,

    In the table you gave me. It mentioned that the Cout should be Non-ceramic. Can I use ceramic series with resistor to replace it. Does the use of ceramic capacitors in the TL5209 cause instability problems?

    Thanks for your support.

    Comi

  • 0 in reply to Comi Li
    TI__Expert 5231 points

    Hi Comi Li,

    Yes, Cout can be ceramic in series with a small resistor. Ceramic capacitors have lower ESR so it is important to pair it with a small resistor so that the device is stable. I think that there is a mistake in the data sheet, and it is saying that the esr resistor should be greater than or equal to 1 ohm. 

    Hope this helps. 

    Thank you,

    Josh Nachassi