JAJU857 December   2022

 

  1.   概要
  2.   リソース
  3.   特長
  4.   アプリケーション
  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 サポート・リソース
    4. 4.4 Trademarks
  10. 5About the Author

3.1.9 Saturation Detection Circuit

The saturation detection circuit is made of the low-side current sense resistor (R7), current sense amplifier INA293, and comparator TLV7011. The comparator outputs high when the fluxgate sensor coil saturation is reached.

This circuit is used to determine when the fluxgate sensor has reached saturation.

GUID-20220801-SS0I-CM90-4S4Q-GJJ3VVH5NXNT-low.gifFigure 3-13 Saturation Detection Schematic

VSENSE is read from the low-side shunt resistor of the DRV8220. VSENSE gives the current through the fluxgate sensor coil. This signal is gained by current sense amplifier INA293, with a fixed gain of 20 V/V. The gained signal is compared to a reference voltage VREF of 500 mV which is sourced from a resistor divider. When the current sense signal passes the VREF voltage, the core has saturated and the DRV8220 must swap output directions. The output of comparator TLV7011 feeds into a DFF which is explained more in the H-Bridge Controlled by DFF section.


GUID-20220817-SS0I-DWCZ-B721-6FTDMCWMNWXX-low.png

Figure 3-14 Burden Resistor Going Into Saturation