SLYA042 July   2024 FDC1004 , FDC1004-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 CSAs and Input Bias Stage
  6. 3 CSA and Gain Error Factor
  7. 4 Applications for Resistance at Input Pins of Current Sense Amplifiers
    1. 4.1 Input Resistance Design Considerations
  8. 5 Applications for Input Resistance at Reference Pins of Current Sense Amplifiers
    1. 5.1 Bidirectional CSA and Applications
    2. 5.2 Driving CSA Reference Pin With High-Resistance Source Voltage
    3. 5.3 Input Resistance at Reference Pin Design Considerations
  9. 6 Design Procedure and Error Calculation for External Input Resistance on CSA
    1. 6.1 Calculating eEXT for INA185A4 With 110Ω Input Resistors
  10. 7 Design Procedure for Input Resistance on Capacitively-Coupled Current Sense Amplifier
    1. 7.1 Bench Verification of Input eEXT for Capacitively-Coupled Current Sense Amplifiers
  11. 8 Design Procedure for Input Resistance at CSA Reference Pins
  12. 9 Input Resistance Error Test with INA185 Over Temperature
    1. 9.1 Schematic
    2. 9.2 Methods
    3. 9.3 Theoretical Model
    4. 9.4 Data for INA185A4 with 110Ω Input Resistors
      1. 9.4.1 Data Calculations
    5. 9.5 Analysis
  13. 10Input Resistance Error Test with INA191 Over Temperature
    1. 10.1 Schematic
    2. 10.2 Methods
    3. 10.3 Theoretical Model
    4. 10.4 Data for INA191A4 With 2.2kΩ Input Resistors
      1. 10.4.1 Data Analysis
    5. 10.5 Analysis
  14. 11Derivation of VOS, EXT for a Single Stage Current Sense Amplifier (CSA)
  15. 12Summary
  16. 13References

10.4.1 Data Analysis

Table 10-6 Typical (Nominal) Shunt Voltage Gain vs. REXT at IN+ and IN-
REXT GTotal, typical
0.0 200.0
2.2kΩ 199.6804386
Table 10-7 Calculated and Predicted Total Gains
TA (°C) -40 25 125
GMeasured (V/V) REXT = 0 199.66932 199.8672363 200.23399
REXT = 2.2kΩ 199.51201 199.66757 200.01409
GPredicted (V/V) REXT = 2.2kΩ 199.395086 199.547887 199.8890043
Prediction Error 0.0586% 0.0599% 0.0625%
Table 10-8 Calculated Gain and Offsets Errors
TA (°C) -40 25 125
EG (%) REXT = 0 -0.165% -0.066% 0.117%
REXT = 2.2kΩ -0.084% -0.006% 0.167%
VOS (µV) REXT = 0 -0.0639 -5.0446 -15.5430
REXT = 2.2kΩ 0.9849 -2.9431 -17.9767
Table 10-9 Calculated Gain and Offset Drift
Temperature Range Δe/(25°C- -40°C) Δe/(125°C- -40°C) Δe/(125°C- 25°C)
EG, Drift (ppm/°C) REXT = 0 15.2 17.1 18.3
REXT = 2.2kΩ 12.0 15.2 17.4
VOS, Drift (nV/°C) REXT = 0 -76.63 -93.81 -104.98
REXT = 2.2kΩ -60.43 -114.92 -150.34
Table 10-10 Calculated and Predicted External Input Resistance Error (eEXT)
TA (°C) -40 25 125
EG, EXT (%) Measured 0.081% 0.060% 0.050%
Predicted 0.022% 0.000% -0.013%
Prediction Error 0.0586% 0.0599% 0.0626%
VOS, EXT (µV) Measured 1.049 2.101 -2.434
Table 10-11 Calculated and Predicted External Input Resistance Error Drift (eEXT, Drift)
Temperature Coefficient Calculation Range Δe/(25°C- -40°C) Δe/(125°C- -40°C) Δe/(125°C- 25°C)
EG Drift, EXT (ppm/°C) Measured -3.24 -1.87 -0.98
Predicted -3.45 -2.12 -1.25
Prediction error 0.21 0.25 0.27
VOS Drift, EXT (nV/°C) Measured 16.19 -21.11 -45.35