SWRA834 May   2025 CC2340R5 , CC2340R5-Q1 , CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Reference Designs
    1. 2.1 LP-EM-CC2340R53
    2. 2.2 LP-EM-CC2340R5
    3. 2.3 LP-EM-CC2340R5-Q1
    4. 2.4 LP-EM-CC2340R5-RGE-4x4-IS24
    5. 2.5 LP-EM-CC2745R10-Q1
  6. 3 Schematic
    1. 3.1 Schematic Overview
      1. 3.1.1 48MHz Crystal
      2. 3.1.2 32.768kHz Crystal
      3. 3.1.3 Filter
      4. 3.1.4 Decoupling Capacitors
      5. 3.1.5 Antenna Components
      6. 3.1.6 RF Shield
    2. 3.2 I/O Pins Drive Strength
    3. 3.3 Bootloader Pins
    4. 3.4 Serial Wire Debug (SWD) Pins
  7. 4 PCB Layout
    1. 4.1 Board Stack-Up
    2. 4.2 LC Filter
    3. 4.3 Decoupling Capacitors
    4. 4.4 Placement of Crystal Load Capacitors
    5. 4.5 Current Return Path
    6. 4.6 DC/DC Regulator
    7. 4.7 Antenna Matching Components
    8. 4.8 Transmission Lines
    9. 4.9 Electromagnetic Simulation
  8. 5 Antenna
  9. 6 Crystal Tuning
    1. 6.1 CC23xx and CC27xx Crystal Oscillators
    2. 6.2 Crystal Selection
    3. 6.3 Tuning the LF Crystal Oscillator
    4. 6.4 Tuning the HF Crystal Oscillator
  10. 7 Optimum Load Impedance
  11. 8 PA Table
  12. 9 Power Supply Configuration
    1. 9.1 Introduction to Power Supply
    2. 9.2 DC/DC Converter Mode
    3. 9.3 Global LDO Mode
  13. 10Board Bring-Up
    1. 10.1 Power On
    2. 10.2 RF Test: SmartRF Studio
    3. 10.3 RF Test: Conducted Measurements
      1. 10.3.1 Sensitivity
      2. 10.3.2 Output Power
    4. 10.4 Hardware Troubleshooting
      1. 10.4.1 No Link: RF Settings
      2. 10.4.2 No Link: Frequency Offset
      3. 10.4.3 Poor Link: Antenna
      4. 10.4.4 Bluetooth Low Energy: Device Does Advertising But Cannot Connect
      5. 10.4.5 Poor Sensitivity: Background Noise
      6. 10.4.6 High Sleep Power Consumption
  14. 11Summary
  15. 12References

4.2 LC Filter

Lay out the LC filter so that crosstalk between the shunt components is minimized. Figure 4-2 shows three different layouts from worst to best. The advantage with the layout to the right is that the parasitic inductance in the PCB track (in black) between the shunt capacitor and the series inductor is in series with the inductor. In the middle figure, the parasitic inductance is in series with the shunt capacitor forming a series LC circuit.

If the design cannot use the reference design as-is (for example, use of a different component size), then the filter probably has to be re-tuned. Simulate both the TI reference design and the custom design using an electromagnetic simulator. The two designs have the same S21 and S22.

LC Filter PCB Layout Design Guideline Figure 4-2 LC Filter PCB Layout Design Guideline