SBOS988A August   2019  – April 2020 DRV425-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  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 Fluxgate Sensor Front-End
        1. 7.3.1.1 Fluxgate Sensor
        2. 7.3.1.2 Bandwidth
        3. 7.3.1.3 Differential Driver for the Internal Compensation Coil
        4. 7.3.1.4 Magnetic Field Range, Overrange Indicator, and Error Flag
      2. 7.3.2 Shunt-Sense Amplifier
      3. 7.3.3 Voltage Reference
      4. 7.3.4 Low-Power Operation
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Linear Position Sensing
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Current Sensing in Busbars
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Decoupling
    2. 9.2 Power-On Start-Up and Brownout
    3. 9.3 Power Dissipation
      1. 9.3.1 Thermal Pad
  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 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1.2 Detailed Design Procedure

Use the following procedure to design a solution for a linear-position sensor based on the DRV425-Q1:

  1. Select the proper supply voltage, VDD, to support the desired magnetic field range (see Table 2 for reference).
  2. Select the proper reference voltage, VREFIN, to support the desired magnetic field range and to match the input voltage specifications of the desired ADC.
  3. Use the RangeCalculator tab in the DRV425 System Parameter Calculator to select the proper shunt resistor value of RSHUNT.
  4. The sensitivity drift performance of a DRV425-Q1 based linear position sensor is dominated by the temperature coefficient of the external shunt resistor. Select a low-drift shunt resistor for best sensor performance.
  5. Use the Problems Detected Table in DRV425 System Parameters tab in the DRV425 System Parameter Calculator to verify the system response.

The amplitude of the magnetic field is a function of distance to, and the shape of, the magnet, as shown in Figure 69. If the magnetic field to be measured exceeds 3.6 mT, see the magnet datasheet to calculate the appropriate minimum distance to the DRV425-Q1 to avoid saturating the fluxgate sensor.

The high sensitivity of the DRV425-Q1 may require shielding of the sensing area to avoid influence of undesired magnetic field sources (such as the earth magnetic field). Alternatively, an additional DRV425-Q1 can be used to perform difference measurement to cancel the influence of a static magnetic field source, as shown in Figure 68. Figure 70 shows the differential voltage generated by two DRV425-Q1 devices in such a circuit.

DRV425-Q1 drv425-q1-differential-linear-position-sensing-using-two-drv425-q1.gifFigure 68. Differential Linear-Position Sensing Using Two DRV425-Q1 Devices