INA193A-EP: How to drive ADC like ADS7042 or similar?

Nicola Fiorucci

Part Number: INA193A-EP
Other Parts Discussed in Thread: ADS7042, INA193

I'm using an INA193A-EP to sense a 30mV to 100mV shunt-based voltage. INA is powered at 5V.

By adding an RC output filter to the INA, is it possible to drive a SAR ADC like ADS7042 or i had to add an OPAMP as buffer?

Thanks

over 2 years ago

0 kai klaas69 over 2 years ago

Guru 140200 points

Hi Nicola,

this depends on the acquisition time of ADC. Have you read section 11.2.1 of datasheet?

As the ADC is rather fast providing an aquisition time of >200ns and the INA193 is rather slow showing a settling time of 2µs for 1% I would probably go for an additional ADC driver.

Kai

0 Peter Iliya over 2 years ago

TI__Mastermind 32395 points

Hey Nicola,

It could be possible given that the conversion and acquisition times are long enough.

You can determine if you have a good RC filter by noting changes in accuracy when increasing acquisition time and/or placing a op amp buffer in between INA193 and ADC.

I would use the INA193 simulation model's ZOUT as a was to get a first-order set of the RC charge bucket values. Here it is below.

Sincerely,

Peter

+1 Javier Contreras4 over 2 years ago in reply to kai klaas69

TI__Mastermind 30450 points

Hi Nicola,

I normally go with the Analog Engineer's Calculator for the RC filter but the like Kai stated it does depend on the speed of the INA193 as well to replenish the capacitor throughout the acquisition time.

See this document. https://www.ti.com/lit/an/sboa443/sboa443.pdf

0 Nicola Fiorucci over 2 years ago in reply to Javier Contreras4

Prodigy 170 points

This is what i'm looking for. Thanks Javier

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INA193A-EP: How to drive ADC like ADS7042 or similar?