TIDUFF8 September   2025

 

  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 LDC5072-Q1
      2. 2.3.2 MSPM0G3507
      3. 2.3.3 TPSM365R3
      4. 2.3.4 TLV9062
  9. 3System Design Theory
    1. 3.1 Hardware Design
      1. 3.1.1 Target PCB
      2. 3.1.2 Coil PCB
      3. 3.1.3 Signal Chain PCB
        1. 3.1.3.1 Inductive Angle Position Sensor Front-End Schematic
        2. 3.1.3.2 Differential to Single-Ended Signal Conversion
      4. 3.1.4 MSPM0G3507 Schematic Design
      5. 3.1.5 Power Supply Design
    2. 3.2 Absolute Position Calculation
    3. 3.3 Software Design
      1. 3.3.1 Angle Calculation Timing
      2. 3.3.2 Rotary Angle Error Sources and Compensation
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 PCB Overview
      2. 4.1.2 Encoder Interface
    2. 4.2 Software
    3. 4.3 Test Setup
    4. 4.4 Test Results
      1. 4.4.1 Inductive Sensor Sine and Cosine Noise Measurement
      2. 4.4.2 Absolute Angle Noise Measurement
      3. 4.4.3 Rotary Angle Accuracy Measurement
      4. 4.4.4 Impact of Air Gap on Noise, 4th Electrical Harmonics and Total Angle Accuracy
      5. 4.4.5 Power Consumption Measurement
  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.     Trademarks
  12. 6About the Author

1.1 Key System Specifications

Table 1-1 provides the key specifications of this reference design.

Table 1-1 TIDA-010961 Key Design Specifications
PARAMETER VALUE (TYPICAL) COMMENT
Function Single-turn inductive absolute angle encoder –
Inductive sensor type LDC5072-Q1 inductive analog front end –
Sense PCB coil outer diameter 58mm –
Sense PCB coil shaft hole 16mm –
Outer coil periods 16 –
Inner coil periods 15 –
Air gap between target and sense PCB 0.5mm (typical), 1.2mm (maximum) Configurable, see definition in Figure 1-1
Angle accuracy ≤ 0.04° Offset and gain error calibrated at 25°C
Angle standard deviation (standard deviation) ≤ 0.0015° –
Angle resolution (ENOB) 16.6 effective number of bits (ENOB) –
Angle resolution (numerical) 32-bit (IQ21) Custom specific on MSPM0G3507
Angle propagation delay (latency) 9.6μs Time from effective sampling point of inductive sense coil to angle calculated
Effective angle sample rate 32kHz Configurable
Maximum operating speed Not tested Change low-pass filter cap to increase, see Section 3.1.3.1
A/D converter Dual 12-bit ADC with 8-times oversampling decimation filter Integrated to MSPM0G3507, ADC oversampling configurable up to 128 times
A/D converter oversampling rate 2.85MSPS
(250ns sample time, 100ns conversion time)		 Configurable sample time, 150ns minimum
Encoder connector 12-pin connector See Table 4-2
Interface UART 2.5M baud rate
Supply voltage 12V ±10% –
Power consumption at 12V input 468 mW –
Operating temperature range –40°C to 125°C Reference design tested at 25°C ambient temperature
Signal chain PCB layers 6 –