ADC121C021: Input capacitor for VA

Yen Nee Lee

Part Number: ADC121C021
Other Parts Discussed in Thread: , LM4120

Hi,

With reference to the reference design in ADC121C021EVM Booster Pack User’s Guide, I would like to confirm that the ADC121C021 will not have any issue without the 4.7uF tantalum cap at the VA input.

In our design we are also using LM4120 as its reference voltage.

Thanks.

over 4 years ago

0 Cynthia over 4 years ago

TI__Mastermind 25070 points

Hello,

The device does need a capacitor on the Va pin, though the 4.7uF tantalum can be left out. A 0.1uF ceramic will suffice.

Regards

Cynthia

0 Yen Nee Lee over 4 years ago in reply to Cynthia

Prodigy 120 points

Hi Cynthia,

From the reference design, a 1nF is used at the ADC121C021 input. Is it ok to follow the reference design?

0 Cynthia over 4 years ago in reply to Yen Nee Lee

TI__Mastermind 25070 points

Hello, apologies for the late response.

The EVM likely used a smaller cap due to the known power supply source would be stable and clean. If you are confident on your design, it may be possible to use a smaller capacitor.

Regards

Cynthia

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ADC121C021: Input capacitor for VA