SBOS775C September   2016  – March 2019 INA302 , INA303

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Bidirectional Current Sensing
      2. 7.3.2 Out-of-Range Detection
      3. 7.3.3 Alert Outputs
        1. 7.3.3.1 Setting Alert Thresholds
          1. 7.3.3.1.1 Resistor-Controlled Current Limit
            1. 7.3.3.1.1.1 Resistor-Controlled Current Limit: Example
          2. 7.3.3.1.2 Voltage-Source-Controlled Current Limit
        2. 7.3.3.2 Hysteresis
    4. 7.4 Device Functional Modes
      1. 7.4.1 Alert Operating Modes
        1. 7.4.1.1 Transparent Output Mode
        2. 7.4.1.2 Latch Output Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Selecting a Current-Sensing Resistor (RSENSE)
        1. 8.1.1.1 Selecting a Current-Sensing Resistor: Example
      2. 8.1.2 Input Filtering
      3. 8.1.3 Using the INA30x With Common-Mode Transients Greater Than 36 V
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.1.1.1 Selecting a Current-Sensing Resistor: Example

In this example, the trade-offs involved in selecting a current-sensing resistor are discussed. This example requires 2.5% accuracy for detecting a 10-A overcurrent event where only 250 mW is allowed for the dissipation across the current-sensing resistor at the full-scale current level. Although the maximum power dissipation is defined as 250 mW, a lower dissipation is preferred to improve system efficiency. Some initial assumptions are made that are used in this example: the limit-setting resistor (RLIMIT) is a 1% component, and the maximum tolerance specification for the internal threshold setting current source (1%) is used. Given the total error budget of 2.5%, up to 0.5% of error can be attributed to the measurement error of the device under these conditions.

As shown in Table 2, the maximum value calculated for the current-sensing resistor with these requirements is 2.5 mΩ. Although this value satisfies the maximum power dissipation requirement of 250 mW, headroom is available from the 2.5% maximum total overcurrent detection error to reduce the value of the current-sensing resistor and to further reduce power dissipation. Selecting a 1.5-mΩ, current-sensing resistor value offers a good tradeoff for reducing the power dissipation in this scenario by approximately 40% and stays within the accuracy region.

Table 2. Calculating the Current-Sensing Resistor, RSENSE

PARAMETER EQUATION VALUE UNIT
DESIGN TARGETS
IMAX Maximum current 10 A
PD_MAX Maximum allowable power dissipation 250 mW
Allowable current threshold accuracy 2.5%
DEVICE PARAMETERS
VOS Offset voltage 30 µV
EG Gain error 0.15%
CALCULATIONS
RSENSE_MAX Maximum allowable RSENSE PD_MAX / IMAX2 2.5 mΩ
VOS_ERROR Initial offset voltage error (VOS / (RSENSE_MAX × IMAX ) × 100 0.12%
ERRORTOTAL Total measurement error √(VOS_ERROR2 + EG2) 0.19%
ERRORINITIAL Initial threshold error ILIMIT tolerance + RLIMIT tolerance 2%
ERRORAVAILABLE Maximum allowable measurement error Maximum error – ERRORINITIAL 1%
VOS_ERROR_MAX Maximum allowable offset error √(ERRORAVAILABLE2 – EG2) 0.48%
VDIFF_MIN Minimum differential voltage VOS / VOS_ERROR_MAX (1%) 6.3 mV
RSENSE_MIN Minimum sense resistor value VDIFF_MIN / IMAX 0.63 mΩ
PD_MIN Lowest-possible power dissipation RSENSE_MIN × IMAX2 63 mW