SBOSA36A January   2021  – July 2021 TMCS1108

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Power Ratings
    6. 7.6 Electrical Characteristics
    7. 7.7 Typical Characteristics
      1. 7.7.1 Insulation Characteristics Curves
  8. 8 Parameter Measurement Information
    1. 8.1 Accuracy Parameters
      1. 8.1.1 Sensitivity Error
      2. 8.1.2 Offset Error and Offset Error Drift
      3. 8.1.3 Nonlinearity Error
      4. 8.1.4 Power Supply Rejection Ratio
      5. 8.1.5 Common-Mode Rejection Ratio
      6. 8.1.6 External Magnetic Field Errors
    2. 8.2 Transient Response Parameters
      1. 8.2.1 Slew Rate
      2. 8.2.2 Propagation Delay and Response Time
      3. 8.2.3 Current Overload Parameters
      4. 8.2.4 CMTI, Common-Mode Transient Immunity
    3. 8.3 Safe Operating Area
      1. 8.3.1 Continuous DC or Sinusoidal AC Current
      2. 8.3.2 Repetitive Pulsed Current SOA
      3. 8.3.3 Single Event Current Capability
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Current Input
      2. 9.3.2 High-Precision Signal Chain
        1. 9.3.2.1 Lifetime and Environmental Stability
        2. 9.3.2.2 Frequency Response
        3. 9.3.2.3 Transient Response
      3. 9.3.3 Internal Reference Voltage
      4. 9.3.4 Current-Sensing Measurable Ranges
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power-Down Behavior
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Total Error Calculation Examples
        1. 10.1.1.1 Room Temperature Error Calculations
        2. 10.1.1.2 Full Temperature Range Error Calculations
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Development Support
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • D|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10.1.1 Total Error Calculation Examples

Total error can be calculated for any arbitrary device condition and current level. Error sources considered should include input-referred offset current, power-supply rejection, input common-mode rejection, sensitivity error, nonlinearity, and the error caused by any external fields. Compare each of these error sources in percentage terms, as some are significant drivers of error and some have inconsequential impact to current error. Offset (Equation 22), PSRR (Equation 23), CMRR (Equation 24), and external field error (Equation 25) are all referred to the input, and so, are divided by the actual input current IIN to calculate percentage errors. For calculations of sensitivity error and nonlinearity error, the percentage limits explicitly specified in the Electrical Characteristics table can be used.

Equation 22. GUID-6C36D471-F34F-49FB-A1B4-FC14E102F284-low.gif
Equation 23. GUID-63FFFB3A-1C03-4D5F-A720-943B2CF48535-low.gif
Equation 24. GUID-2D2E2FFA-D608-4117-9380-DFF8F94ADDA6-low.gif
Equation 25. GUID-1EEBC7AA-A5E9-42A7-B96D-DEFFAE894101-low.gif

When calculating error contributions across temperature, only the input offset current and sensitivity error contributions vary significantly. For determining offset error over a given temperature range (ΔT), use Equation 26 to calculate total offset error current. Sensitivity error is specified for both –40°C to 85°C and –40°C to 125°C. The appropriate specification should be used based on application operating ambient temperature range.

Equation 26. GUID-02D314E4-3B9A-4D76-8751-946F6B172B5B-low.gif

To accurately calculate the total expected error of the device, the contributions from each of the individual components above must be understood in reference to operating conditions. To account for the individual error sources that are statistically uncorrelated, a root sum square (RSS) error calculation should be used to calculate total error. For the TMCS1108, only the input referred offset current (IOS), CMRR, and PSRR are statistically correlated. These error terms are lumped in an RSS calculation to reflect this nature, as shown in Equation 27 for room temperature and Equation 28 for across a given temperature range. The same methodology can be applied for calculating typical total error by using the appropriate error term specification.

Equation 27. GUID-B7F546BF-91AC-4F03-B919-72EF9C38E99A-low.gif
Equation 28. GUID-5C11EDD5-97AD-4749-A845-09BC78D86554-low.gif

The total error calculation has a strong dependence on the actual input current; therefore, always calculate total error across the dynamic range that is required. These curves asymptotically approach the sensitivity and nonlinearity error at high current levels, and approach infinity at low current levels due to offset error terms with input current in the denominator. Key figures of merit for any current-measurement system include the total error percentage at full-scale current, as well as the dynamic range of input current over which the error remains below some key level. Figure 10-1 illustrates the RSS maximum total error as a function of input current for a TMCS1108A2B at room temperature and across the full temperature range with VS of 5 V.

Figure 10-1 RSS Error vs Input Current