TIDUF03 December   2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 System Design Theory
      1. 2.2.1 Detection Principals
      2. 2.2.2 Saturation
      3. 2.2.3 General Mode of Operation
    3. 2.3 Highlighted Products
      1. 2.3.1 DRV8220
      2. 2.3.2 OPAx202
      3. 2.3.3 TLVx172
      4. 2.3.4 TLV7011
      5. 2.3.5 INA293
      6. 2.3.6 SN74LVC1G74
      7. 2.3.7 TLV767
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware
      1. 3.1.1  Board Overview
      2. 3.1.2  Filter Stage
      3. 3.1.3  Differential to Single-Ended Converter
      4. 3.1.4  Low-Pass Filter
      5. 3.1.5  Full-Wave Rectifier
      6. 3.1.6  DC Offset Circuit
      7. 3.1.7  Auto-Oscillation Circuit
        1.       31
      8. 3.1.8  DRV8220 H-Bridge
      9. 3.1.9  Saturation Detection Circuit
      10. 3.1.10 H-Bridge Controlled by DFF
      11. 3.1.11 MCU Selection
      12. 3.1.12 Move Away From Timer Capture
      13. 3.1.13 Differentiating DC and AC From the Same Signal
      14. 3.1.14 Fluxgate Sensor
    2. 3.2 Software Requirements
      1. 3.2.1 Software Description for Fault Detection
    3. 3.3 Test Setup
      1. 3.3.1 Ground-Fault Simulation
    4. 3.4 Test Results
      1. 3.4.1 Linearity Over Temperature
    5. 3.5 Fault Response Results
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Documentation Support
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  10. 5About the Author

3.1.8 DRV8220 H-Bridge

The DRV8220 drives current through the magnetic core to saturate the core. This device is the smallest, most cost-effective device capable of driving enough current.

The DRV8220 is an integrated motor driver with four N-channel power FETs, charge pump regulator, and protection circuitry. The device can supply up to 1.76 A of output current, operating on a supply voltage from 4.5 V to 18 V. The driver offers robust internal protection including undervoltage lockout, output overcurrent, and device overtemperature.

The low-side current sense resistor (R7) detects current through the DRV8220. The current spikes when the core reaches saturation, which is read by the saturation detection circuit.

The output of the DRV8220 is controlled by pins 1 and 2. The state of these pins determines which direction current flows through the magnetic coil. When the saturation detection circuit threshold is passed, the control signals to pins 1 and 2 flip, which flips the DRV8220 output.

DRV8220 output 1 and 2 are used to drive are used to drive the fluxgate sensor coil to saturation. The low-side current sense resistor is used by the saturation detection circuit to know when saturation is reached.

GUID-20220801-SS0I-NS7G-66DG-5MNHKKSV0FBN-low.gifFigure 3-12 DRV8220 Schematic

The current through VSENSE peaks when the core reaches saturation.