DS280DF810: The capacitor for the input pin

Lacey Lin

Part Number: DS280DF810

Hi team,

The DS280DF810 has integrated the 220nF cap. but in the application of my customer, they need to add a cap before the input pin. What's the value of the cap you may recommend to keep the signal integrity?

Lacey

Thanks a lot!

over 8 years ago

0 Lee Sledjeski over 8 years ago

TI__Mastermind 43795 points

Hi Lacey,

I do not understand the need to place another capacitor in series with the input pin to help with signal integrity. Can you explain the requirement to add an additional AC coupling capacitor?

Thanks and Regards,

Lee

0 Lacey Lin over 8 years ago in reply to Lee Sledjeski

TI__Intellectual 2900 points

Hi Lee,

To place the cap is the one of the application of my customer, not to keep the signal integrity. Because there are two input signal, they wants to choose one of them by putting a cap. But I am afraid that the cap will affect the signal integrity, so I want yor help to choose a recommended valu for the cap. Or can I put a 0 resister before the input.

Lacey

Thanks a lot

0 Lee Sledjeski over 8 years ago in reply to Lacey Lin

TI__Mastermind 43795 points

Hi Lacey,

It may be better to use a 0 ohm resistor to keep a low impedance connection to the common mode voltage across the entire net. I would definately recommend using the 0201 footprint since it tends to be a minimal disruption due to the small size. It is also critical to share the footprint pad between the mux paths so no transmission line stubs are created.

If using a capacitor I would recommend a 220nF value. It is a good AC coupling capacitor value.

Regards,

Lee

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DS280DF810: The capacitor for the input pin