ADC124S021: Question about ope-amp which drives IN1~IN4 of ADC124S021.

Kazuya Nakai59

Guru 20080 points

Part Number: ADC124S021

Hello guys,

One of my customers is considering using ADC124S021 for their next products.

They have the following question about ope-amp which drives IN1~IN4 of ADC124S021.

Could you please give me your reply?

Q. When a ope-amp is connected to INx of ADC124S021, what is the ope-amp output driving capablity for high accuracy conversion?

Is it ok if the ope-amp has the capablity which charges 33pF (Input capacitance) to target voltage during track mode (3 SCLK period)?

Your reply would be much appreciated.

Best regards,

Kazuya.

over 3 years ago

0 Cynthia over 3 years ago

TI__Mastermind 24940 points

Hello,

The customer understanding is correct. The Amplifier needs to be able to drive the ADC sample and hold capacitor within the acquisition time, which for the ADC124S021 is 3 SCLK pulses. keep in mind that a RC circuit is also necessary at the output of the amplifier to the input of the ADC.

I suggest watching the following two videos to further understand how to chose the correct amplifier for your application. The slide decks are also available.

Introduction to SAR ADC Front-End Component Selection

Selecting and Verifying the Driver Amplifier

Regards

Cynthia

0 Kazuya Nakai59 over 3 years ago in reply to Cynthia

Guru 20080 points

Hello Cynthia,

Thank you very much for your reply.

It is very helpful for the customer and me.

Thank you again and best regards,

Kazuya.

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ADC124S021: Question about ope-amp which drives IN1~IN4 of ADC124S021.