INA296B-Q1: Input resistance value shown in the block diagram

DEVENDHIRAN KUMARASAMY

Prodigy 150 points

Part Number: INA296B-Q1

Tool/software:

Hi,

What is the resistance value (marked in the image below) of the INA296x part?

Regards,

Devendhiran K

over 1 year ago

0 Javier Contreras4 over 1 year ago

TI__Mastermind 33240 points

Hello Devendhiran,

This is just a block diagram and resistance vary with gain. The best way to get what you need is to use the simulations for IB vs Vsense and IB vs VCM. These are also modeled in the spice model.

Regards,

Javier

0 DEVENDHIRAN KUMARASAMY over 1 year ago in reply to Javier Contreras4

Prodigy 150 points

Hi Javier,

Thanks for your feedback.

I have simulated using the INA296B3 spice model and found that bias current flowing into the IN+ & IN- pins of INA296B3 are not same with respect to the VCM voltage at the input pins.

Is this the actual behavior of the INA296Bx current sense amplifier?

Also, we need to use 1K ohm series resistor at the input path of IN+ & IN- pins of CSA. Does it alter the gain or functionality of the CSA? If yes, is there any method to evaluate the impact?

Regards,

Devendhiran K

0 Javier Contreras4 over 1 year ago in reply to DEVENDHIRAN KUMARASAMY

TI__Mastermind 33240 points

Hello Devendhiran,

This is the IB of the device and you can see plots in the datasheet of IB vs Vsense and IB vs VCM. I would not recommend larger than 10Ω in series to maintain higher accuracy. Most current sense amplifiers have this input bias currents. Below is a video on the impact and a post on an estimate of the error.

https://www.ti.com/video/6219017476001

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1261093/ina296b4q---gain-error-factor

Regards,

Javier

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INA296B-Q1: Input resistance value shown in the block diagram