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Guide
Ideal Shunt Resistor : An ideal shunt resistor is a resistor with zero percent tolerance error and has zero variation over temperature
Sensed Current Range: These fields allow the user to select an operational current range they are interested in.
Common Mode Voltage: The Common Mode voltage range needed is determined by the node voltage the device is connected to where the current is being measured.
Supply Voltage: Supply voltage is the voltage required for device operation.
Operating Temperature: The error curve will be generated at room temperature (25°C) and the specified temperature.
(The limits for each parameter are preset by the selected TI device)
Help
NOTE 1:
This error tool calculates the root sum square (RSS) error as opposed to worst case error. Worst case error assumes all error sources are simultaneously at the worst value. This is an unlikely scenario. The RSS error methodology is a more realistic worst case system error condition.
NOTE 2:
The room temperature curve is calculated from the following equation:
e =
(
V OS
V SHUNT
+
|V CMSYS - VCMDS| x CMRR
V SHUNT
+
|V SSYS - VSDS| x PSRR
V SHUNT
)
2
+
(eGN)
2
| VOS |
|
Amplifier offset voltage at 25 ° C |
| VSHUNT |
|
Sensed current multiplied by shunt resisto |
| VCMSYS |
|
Chosen common mode voltage |
| VCMDS |
|
Data sheet specified common mode voltage for VOS |
| CMRR |
|
Amplifier specified common mode rejection in V/V |
| VSSYS |
|
Chosen supply voltage |
| VSDS |
|
Data sheet specified supply voltage for VOS |
| eGN |
|
Amplifier gain error |
For the at temperature curve, the drift specified in the data sheet is added to both the V
OS term and the e
GN term.
Additional error sources such as amplifier linearity, bias current, and reference voltage input are not included in this analysis. The effect of these errors sources can be found in the individual device datasheets.
More information on calculating error can be found in the Getting Started with Current Sense Amplifier Video Training Series.
