SBOA511A March   2021  – September 2021 INA209 , INA219 , INA220 , INA220-Q1 , INA226 , INA226-Q1 , INA228 , INA228-Q1 , INA229 , INA229-Q1 , INA230 , INA231 , INA232 , INA233 , INA234 , INA236 , INA237 , INA237-Q1 , INA238 , INA238-Q1 , INA239 , INA239-Q1 , INA260 , INA3221 , INA3221-Q1

 

  1.   Trademarks
  2. 1 Introduction
  3. 2 Defining Constraints
  4. 3 Find The Maximum Shunt Value
  5. 4 Find The Minimum Shunt Value
  6. 5 Maximum Resolution or Minimum Shunt Loss
  7. 6 What to Do if the Measurement Range Is Insufficient
  8. 7 Determine the Current LSB and Calibration Coefficient
  9. 8 Programming Your Device Registers
  10. 9 Summary
  11. 10Revision History

2 Defining Constraints

The first and most crucial step for designing with a digital power monitor is to define your system constraints for the device. These include the common mode voltage expected at the sense pins, the supply voltage you would like to use, the maximum current you want to measure, and the minimum current you want to measure. Common mode voltage and supply voltage are two specifications that can easily be extracted from the data sheet and used to narrow down your options. These specifications must be adhered to insure the device operates correctly and is not damaged. As for the current range the device can measure, the data sheet does not provide any bounds that can be simply looked up. The bounds are not only dependent on device specifications, but on design goals that include shunt power dissipation and resolution. The ensuing steps will provide details on how to assess a given device's current measurement bounds and determine if it will be adequate for your needs.