SBOA603 June 2024 INA700 , INA740A , INA740B , INA745A , INA745B , INA780A , INA780B
3.3 Total Error Comparison for Current ≤ 50A Over Temperature
The INA780A characterized for 75A at 25°C was the EZShunt™ device selected alongside our INA238 and the below resistor set to calculate the performance difference between our external and integrated shunt designs:
| Data sheet | Measured | |||||||
|---|---|---|---|---|---|---|---|---|
| Resistor | Resistance (mΩ) | Tolerance | Drift (ppm) | Tolerance | Drift (ppm) | Wattage (W) | Case Size | 1K price |
| G | 0.5 | 1% | 50 | 0.3% | 44.8 | 3 | 1216 | $0.26 |
| H | 0.5 | 1% | 50 | 4.74% | 65.5 | 2 | 2512 | $0.34 |
| I | 0.5 | 1% | 75 | 0.4% | 3.6 | 3 | 2726 | $0.42 |
Figure 3-10 INA780A vs INA238 and Resistor GBy comparing both designs against one another at two separate ambient temperatures, we are able to see how the Discrete design comprised of our Ultra-precise INA238 and Resistor G with a measured tolerance of 0.3% and drift of 44.8ppm can have slightly greater accuracy at both 25°C and 125°C against our high voltage EZShunt™ device being the INA780A.
Figure 3-11 INA780A vs INA238 and Resistor HWhen using Resistor H in the discrete design, we can visualize our INA780A can have much higher accuracy and less total error from approximately 0.1 to 50A while the discrete design can be slightly better from 0A to approximately 0.1 at both 25°C and 125°C. This can be attributed towards the measured tolerance percentage subjugated upon the system by Resistor E of 4.49%.
Figure 3-12 INA780A vs INA238 and Resistor IAccording to this data set, using a more premium resistor I providing a tolerance error of 0.4% and drift of 3.6ppm, The discrete design comprised of our INA238 and Resistor I can help provide a more precise design at both 25°C and 125°C when compared to the INA780A.