TIDUF97 September   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 TMAG6180-Q1
      2. 2.3.2 MSPM0G3507
      3. 2.3.3 THVD1454
  9. 3System Design Theory
    1. 3.1 Hardware Design
      1. 3.1.1 Angle Sensor Schematic Design
      2. 3.1.2 MSPM0G3507 Schematic Design
      3. 3.1.3 RS485 Transceiver Schematic Design
      4. 3.1.4 Power Supply and Reference Voltage
    2. 3.2 Software Design
      1. 3.2.1 Angle Calculation Timing
      2. 3.2.2 Rotary Angle Calculation
      3. 3.2.3 Rotary Angle Error Sources and Compensation
      4. 3.2.4 Encoder Communication Interface
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 PCB Overview
      2. 4.1.2 Encoder and JTAG Interface
      3. 4.1.3 Software Requirements
    2. 4.2 Test Setup
    3. 4.3 Test Results
      1. 4.3.1 AMR Sensor Sin and Cos Outputs Measurement
      2. 4.3.2 Static Angle Noise Measurement
      3. 4.3.3 Rotary Angle Accuracy Measurement
        1. 4.3.3.1 Impact of Airgap on Noise, Harmonics, and Total Angle Accuracy
      4. 4.3.4 RS485 Interface and Signal Integrity
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout
      4. 5.1.4 Altium Project Files
      5. 5.1.5 Gerber Files
      6. 5.1.6 Assembly Drawings
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Authors

3.1.1 Angle Sensor Schematic Design

TIDA-010947 AMR Sensor TMAG6180 Schematic Figure 3-1 AMR Sensor TMAG6180 Schematic

A 100nF decoupling capacitor C11 is added close to the TMAG6180’s VCC and GND pin. Q0 and Q1 are open-drain outputs, and 100k pull-up resistors R7 and R9 are connected to 3.3V power rail.

The TLV9062 is optional and used to convert the TMAG6180-Q1 differential analog outputs SIN_P, SIN_N and COS_P, COS_N to a single-ended signal to connect to the MSPM0G3507 ADC. There is the possibility to bypass TLV9062 by populating R8, R11, R12 , R13, R16, R18 as 0Ω resistor. To make sure the stable supply voltage at VCC, C15(100nF) is placed between VCC and GND.

The differential gain of TLV9062 can be calculated by Equation 1.

Equation 1. V o V i n = R 12 R 8 = R 19 ∥ R 23 R 17 = 1 2

Chose unit gain and let R8 be 10kΩ, so R17and R20 needs to be 10kΩ, R12 needs to be 5kΩ.

C18 is added to filter out high frequency noise. The bandwidth (BW) can be calculated by Equation 2.

Equation 2. B W = 1 2 πC 18 R 12 = 1 2 π ( C 20 ∥ C 22 ) ( R 19 ∥ R 23 )

Chose 3MHz bandwidth, C18 can C19 needs to be 10pF. C20 approximately C23 needs to be half of C18, which is 5pF.