Other Parts Discussed in Thread: INA138, TIDA-00332, ISO1541, TIDA-00313, INA226, ISOW7842, INA260
Hi,
The common mode voltage of INA196 is limited to 80V.
How can I extend the common mode range of INA196 to measure a 110V DC rail with a peak current capacity of 1A?
Can I use a resistor divider at the sensing input of INA196 as shown in the image?
Also, please verify whether my calculations are correct.
To meet the common mode requirement of INA196, choose the value of resistors accordingly
RD1 = RD3 = 220K
RD2 = RD4 = 432K
The scaling factor due to resistor divider is 0.6626
The common mode voltage at V+ and V- = 110V approximately
The common mode voltage of 110V can't be handled by INA196. So use a resistor divider to scale
them below 80V.
The actual common mode voltage at input of INA196 at IN+ and IN- = 110V * 0.6629 = 66.29V.
Now the common mode voltage of 66.29 can be withstood by IN196.
When a current of 500mA is flowing through the 20milli-ohm resistor,
the voltage at output of INA 196 is given by
= Current through shunt * Shunt resistor * scaling factor * INA196 gain
= 0.5 * 0.020 * 0.6629 * 20 = 0.13258V
Based on above calculation, I am getting 0.1325V for 500mA current. Do this calculation is correct?
Thanks in advance
DEEPAK V