JAJU835 December   2021

 

  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
      1.      10
    2. 2.2 Highlighted Products
      1. 2.2.1 DRV5056
      2. 2.2.2 DRV5032
      3. 2.2.3 TPS709
      4. 2.2.4 SN74HCS00
      5. 2.2.5 TPS22917
      6. 2.2.6 SN74AUP1G00
      7. 2.2.7 TLV9061
    3. 2.3 Design Considerations
      1. 2.3.1 Design Hardware Implementation
        1. 2.3.1.1 Hall-Effect Switches
          1. 2.3.1.1.1 U1 Wake-Up Sensor Configuration
          2. 2.3.1.1.2 U2 Stray-Field Sensor Configuration
          3. 2.3.1.1.3 U3 and U4 Tamper Sensor Configuration
          4. 2.3.1.1.4 Hall Switch Placement
            1. 2.3.1.1.4.1 Placement of U1 and U2 Sensors
              1. 2.3.1.1.4.1.1 U1 and U2 Magnetic Flux Density Estimation Results
            2. 2.3.1.1.4.2 Placement of U3 and U4 Hall Switches
              1. 2.3.1.1.4.2.1 U3 and U4 Magnetic Flux Density Estimation Results
          5. 2.3.1.1.5 Using Logic Gates to Combine Outputs from Hall-Effect Switches
        2. 2.3.1.2 Linear Hall-Effect Sensor Output
          1. 2.3.1.2.1 DRV5056 Power
          2. 2.3.1.2.2 DRV5056 Output Voltage
          3. 2.3.1.2.3 DRV5056 Placement
        3. 2.3.1.3 Power Supply
        4. 2.3.1.4 Transistor Circuit for Creating High-Voltage Enable Signal
      2. 2.3.2 Alternative Implementations
        1. 2.3.2.1 Replacing 20-Hz Tamper Switches With 5-Hz Tamper Switches
        2. 2.3.2.2 Using Shielding to Replace Tamper Switches and Stray Field Switch
        3. 2.3.2.3 Replacing Hall-Based Wake-Up Alert Function With a Mechanical Switch
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1 Installation and Demonstration Instructions
      2. 3.1.2 Test Points and LEDs
      3. 3.1.3 Configuration Options
        1. 3.1.3.1 Disabling Hall-Effect Switches
        2. 3.1.3.2 Configuring Hardware for Standalone Mode or Connection to External Systems
    2. 3.2 Test Setup
      1. 3.2.1 Output Voltage Accuracy Testing
      2. 3.2.2 Magnetic Tampering Testing
      3. 3.2.3 Current Consumption Testing
    3. 3.3 Test Results
      1. 3.3.1 Output Voltage Accuracy Pre-Calibration Results
      2. 3.3.2 Output Voltage Accuracy Post-Calibration Results
      3. 3.3.3 Magnetic Tampering Results
      4. 3.3.4 Current Consumption Results
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 サポート・リソース
    5. 4.5 Trademarks

2.2.2 DRV5032

The DRV5032 device is an ultra-low-power digital switch Hall-effect sensor, designed for the most compact and battery-sensitive systems. The device is offered in multiple magnetic thresholds, sampling rates, output drivers, and packages to accommodate various applications. Table 2-1 (from the data sheet) shows a comparison between the different DRV5032 device variants.

Table 2-1 DRV5032 Device Variants
VERSION MAXIMUM
THRESHOLD		 MAGNETIC
RESPONSE		 OUTPUT
TYPE		 SAMPLING
RATE		 PACKAGES
AVAILABLE
DRV5032DU 3.9 mT Unipolar Push-pull 20 Hz SOT-23, X2SON, TO-92
DRV5032FA 4.8 mT Omnipolar Push-pull 20 Hz SOT-23, X2SON, TO-92
DRV5032FB Omnipolar Push-pull 5 Hz SOT-23, TO-92
DRV5032FC Omnipolar Open-drain 20 Hz SOT-23, TO-92
DRV5032FD Unipolar Push-pull 20 Hz X2SON, TO-92
DRV5032AJ 9.5 mT Omnipolar Open-drain 20 Hz SOT-23, X2SON, TO-92
DRV5032ZE 63 mT Omnipolar Open-drain 20 Hz SOT-23, TO-92

Figure 2-5 shows the direction of sensitivity for the different DRV5032 device variants. When the applied magnetic flux density exceeds the BOP threshold, the device outputs a low voltage. The output stays low until the flux density decreases to less than BRP, and then the output either drives a high voltage or becomes high impedance, depending on the device version. By incorporating an internal oscillator, the device samples the magnetic field and updates the output at a rate of 20 Hz, or 5 Hz for the lowest current consumption. Omnipolar and unipolar magnetic responses are available.

Figure 2-5 DRV5032 Direction of Sensitivity

In the design, the X2SON package of the DRV5032DU is used for the wake-up (U1) and stray field sensors (U2). This device variant is selected for both of these sensors because it was unipolar and had both a positive-responding and negative-responding output. In addition, the 3.9-mT BOP threshold works well for the selected magnet and magnet to sensor distances used in this design.

The SOT-23 package of the DRV5032FA is selected for the U3 and U4 tamper switches. This device is selected for the following reasons:

  • It is omnipolar, which means it could respond to both a strong positive and a strong negative field from external magnets
  • It uses a push-pull output, which consumes less current than an open-drain output type
  • The 4.8-mT BOP threshold works well for the selected magnet and magnet-to-sensor distances used in this design
  • The 20-Hz sampling rate allows detecting external magnetic fields in 50 ms compared to the 200-ms detection rate if a 5-Hz device variant is selected. If the system can use a 200-ms detection rate, the DRV5032FA in this design can be replaced with a DRV5032FB to reduce system current consumption.