ST STEVAL-WLC38RX - Table 11. Maximum Power for Z-Axis Gaps; Figure 58. Efficiency Curves for Various Misalignments in the Z-Axis

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Figure 58. Efficiency curves for various misalignments in the Z-axis

Table 11. maximum power for Z-axis gaps

Z gap [mm]

Maximum power(1) [W]

4 5.002

6 5.000

8 5.001

11 5.000

13 5.000

16 3.093

(1) The maximum power is also limited by the transmitter, as STEVAL-WBC86TX is only BPP compatible

ARC mode also improves performance at higher Z-axis distances. The following waveform shows how STWLC38

is able to establish communication even at a high Z-distance (16 mm), and after reaching the default 6 V VRECT

threshold, switches to a different operating mode where output can be enabled.

UM3154

Typical performance characteristics

UM3154 - Rev 2

page 52/81

Main Page

Figure 1. STEVAL-WLC38RX Evaluation Board1
Get Started2
Reference Design Specifications3
Table 1. Reference Design Specifications3
Overview of the Board4
Figure 2. Main Board Elements4
Test Points5
Table 2. Header and Test Point Descriptions5
Figure 3. Headers and Test Points5
Basic Operating Modes6
Functional Check6
Figure 4. Transmitter and Receiver Boards Setup6
Graphical User Interface (GUI)7
Connecting STWLC38 to PC GUI7
Figure 5. PC GUI Main Screen7
Patch and Configuration Files8
Configuration File Generation8
Figure 6. Device Selection and Connection8
Figure 7. Save RX Button9
Figure 8. Configuration ID Field9
Header File10
Header File Generation10
Figure 9. Save Folder Selection10
Figure 10. Device Selection10
Figure 11. Confirmation of Patch Version11
Figure 12. Header File Save11
Programming the Device12
Figure 13. Loading the Header File12
Figure 14. Loading the Patch and Configuration Files13
Device Description and Operation14
System Block Diagram14
Figure 15. STWLC38 System Block Diagram14
Integrated Power Rectifier15
Internal ADC Channels Monitor15
Main LDO Regulator15
Figure 16. PC GUI Charts15
Chip under Voltage Lockout16
Chip Enable16
Power up Sequence16
Ldos16
Protections Overview16
Soft Overvoltage Protection (SOVP)18
Figure 17. SOVP Rx Protection Threshold Setting18
Hard Overvoltage Protection (HOVP)19
Figure 18. SOVP Rx Protection Settings19
Figure 19. HOVP Rx Protection Threshold Setting19
Figure 20. HOVP Rx Protection Settings20
Figure 21. VRECT and OVP Thresholds20
Firmware OVP21
Overcurrent Protections (OCP)21
Figure 22. Firmware Rx Protection Threshold Setting21
Figure 23. Firmware Rx Protection Settings21
Figure 24. over Current Protection Threshold Setting22
Figure 25. Hardware Overcurrent Rx Protection Selection22
Overtemperature Protections (OVTP)23
Figure 26. Firmware Overcurrent Rx Protection Threshold Setting23
Figure 27. Firmware Overcurrent Rx Protection Settings23
Figure 28. Hardware Overtemperature Rx Protection Threshold Setting24
Figure 29. Hardware Overtemperature Rx Protection Settings24
NTC Protection25
Figure 30. Firmware Overtemperature Rx Protection Threshold Setting25
Figure 31. Firmware Overtemperature Rx Protection Settings25
Foreign Object Detection (FOD)26
Figure 32. NTC Rx Protection Threshold Setting26
Figure 33. NTC Rx Protection Settings NTC ADC26
WPC Qi Wireless Power Transfer27
Wireless Power Interface27
Qi Baseline Power Profile28
Figure 34. Qi Baseline Power Profile Flowchart28
Qi Extended Power Profile (EPP)29
Bidirectional Communication29
Figure 35. Qi Extended Power Profile Flowchart29
ASK Communication30
Table 3. HI and lo State Parameters30
Figure 36. HI and lo States in ASK Communication30
Figure 37. Example of a Differential Bi-Phase Encoding Scheme31
Figure 38. Example of Asynchronous Serial Format31
FSK Communication32
Figure 39. ASK Modulation Capacitor Connections32
Figure 40. Example of Differential Bi-Phase Encoding32
Most Common Qi Communication Packets33
Figure 41. Format of Three Defined Responses33
Adaptive Rectifier Configuration (ARC) Mode34
Table 4. EPT Codes34
I²C Interface35
Table 5. Possible Separation Without and with ARC Mode35
Figure 42. STEVAL-WBC86TX and STEVAL-WLC38RX Setup35
Data Validity36
Start and Stop Conditions36
Byte Format36
Interface Protocol36
Writing to a Single Register36
Figure 43. Writing to a Single I²C Register36
Writing to Multiple Registers with Incremental Addressing37
Reading from a Single Register37
Reading from Multiple Registers with Incremental Addressing37
Figure 44. Writing to Multiple I²C Registers37
Figure 45. Reading from a Single I²C Register37
Figure 46. Reading from Multiple I²C Registers37
Gpiox and INTB Pins38
Interrupt Registers38
Table 6. GPIO Pins38
Figure 47. Interrupt Register Settings39
Schematic Diagrams40
Figure 48. STEVAL-WLC38RX Circuit Schematic40
Bill of Material (BOM)41
Table 7. STEVAL-WLC38RX BOM41
STEVAL-WLC38RX Description and Operation43
STEVAL-WLC38RX Coil Description43
Table 8. Electrical Characteristics of the Receiver Coil43
Figure 49. Mechanical Characteristics of the Receiver Coil 143
Figure 50. Mechanical Characteristics of the Receiver Coil 244
Figure 51. Mechanical Characteristics of the Receiver Coil 344
STEVAL-WLC38RX PCB Layout45
Figure 52. STEVAL-WLC38RX PCB Layout Top Layer45
Figure 53. STEVAL-WLC38RX PCB Layout Inner 1 Layer46
Figure 54. STEVAL-WLC38RX PCB Layout Inner 2 Layer47
STWLC38 Default Configuration48
Table 9. STWLC38 Default Configuration48
Figure 55. STEVAL-WLC38RX PCB Layout Bottom Layer48
Typical Performance Characteristics49
Power up Waveforms49
Table 10. Typical Performance Characteristics49
Efficiency and Spatial Freedom in the XY Plane50
Figure 56. Power up Waveforms of a STEVAL-WLC38RX and STEVAL-WBC86TX Setup50
Spatial Freedom in the Z-Axis51
Figure 57. Efficiency Curves for Various Misalignments in the X-Axis51
Table 11. Maximum Power for Z-Axis Gaps52
Figure 58. Efficiency Curves for Various Misalignments in the Z-Axis52
Thermal Performance53
Figure 59. STEVAL-WLC38RX Communication Performance at High Z Distances53
Figure 60. Thermal Performance with a 5 W Load (5 V/1 A) after 5 Minutes53
Figure 61. Thermal Performance with a 15 W Load (9 V/1.7 A) after 5 Minutes54
Designing a 5 W Qi BPP or 15 W Qi EPP Wireless Power Receiver Based on55
STEVAL-WLC38RX Evaluation Board55
External Component Design55
Coil Selection55
Series and Parallel Resonant Capacitor Selection55
VRECT and VOUT Capacitor Selection55
ASK Modulation Capacitor Selection and Configuration55
Table 12. Default STWLC38 ASK Configuration56
Figure 62. Rx ASK Configuration56
SOVP Clamp Resistor Selection57
ESD/TVS Diodes57
NTC Thermistor Connection57
Figure 63. the Transition from Low Current to Normal Current and the Effect on Modulation57
PCB Layout Guidelines58
LDO Output Voltage Configuration58
Figure 64. External NTC Connection58
Figure 65. Default LDO Configuration59
Figure 66. Default LDO Drop Curve59
FOD Tuning60
Bpp60
Figure 67. Cleared Rx FOD Tuning Registers60
Figure 68. FOD Tuning Tab60
Figure 69. Load Adjustment61
Figure 70. Rx/Tx Power Difference Curve61
Figure 71. Tuning to Obtain a Flat BPP FOD Curve62
Figure 72. Compensated Values62
Epp63
Figure 73. Cleared EPP FOD Settings63
Figure 74. Tuning to Obtain a Flat EPP FOD Curve63
Reference Code with STM32 Development Boards64
Hardware Requirements64
Hardware Connections64
Software Requirements64
Figure 75. Rf - Qf64
Figure 76. Pin Connection between Host and STWLC38 Chip/Evaluation Board64
Source Files65
Reference Code Porting Procedure65
Api66
Table 13. Stwlc38_Write_Fwreg66
Table 14. Stwlc38_Read_Fwreg66
Table 15. Stwlc38_Get_Chip_Info66
Table 16. Stwlc38_Fw_Update66
Error Codes67
Common Testing and Debugging Issues67
Table 17. Error Codes and Descriptions67
Table 18. Common Issues and Causes67
Board Versions68
Table 19. STEVAL-WLC38RX Versions68
Qi Certification69
Figure 77. Qi Certification Flowchart69
Regulatory Compliance Information70
Appendix71
Figure 78. Temperature before Power Transfer Maximum 25⁰C on STEVAL-WBC86TX71
Figure 79. Maximum Temperature of the Board after 2Hours (40.8⁰C) - 5W Power Transfer STEVAL-WLC38RX72
Figure 80. Maximum Temperature of the Board after 2Hours (42.5⁰C) - 5W Power Transfer72
Figure 81. Maximum Temperature of the Board and Plastic Case after 2Hours (33.5⁰C) - 5W Power Transfer73
Revision History74
Table 20. Document Revision History74

ST STEVAL-WLC38RX - Table 11. Maximum Power for Z-Axis Gaps; Figure 58. Efficiency Curves for Various Misalignments in the Z-Axis

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