INA282-Q1: INA282-Q1:

Hello,

We are using external ADC (ADS1118IDGSR) . for current sensing by IC INA282-Q1. We have connected shunt resister of value 0.0001ohm(connected 0.0003ohm in parallel manner) at high side of battery. we have configured device INA282-Q1 in following manner.

 so we are following below mentioned steps to get physical value of current from raw value.

Full-Scale Range (FSR) and LSB Size of EADC(ADS1118)

A programmable gain amplifier (PGA) is implemented before the ADS1118 core. The full-scale range is configured by three bits (PGA[2:0]) in the Config Register and can be set to ±6.144 V, ±4.096 V, ±2.048 V,±1.024 V, ±0.512 V, ±0.256 V.

LSB = FSR / 2^16 (Datasheet)

FSR= ±4.096 V we are using

LSB=125microV

INA282Q1

INA 282 Q1 purpose here -

• Its providing the gain of 50
• Its using the zero drift.

The O/P pin of this IC is having the minimum voltage range as (GND-0.3)V

The VREF1 and VREF2 that we are using is 2.5V.

Calculation-

we are getting raw count as- 20071

The EADC OP voltage will be- LSB*20071

LSB=125microV

So EADC Output V= 125micro*20071=2.508875 V

Since, we were adding the offset of 2.5V so the voltage will be 2.508875-2.5=0.008875V

This was given a gain of 50, so the V will be=0.00875/50=0.000175V

The resistor used is 0.0001ohm

So current will be 0.000175/0.0001=1.75A

For this calculation we are not getting expected current value. so kindly let us know, if we are missing something?

Regards;

Utsav Shah