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ST STEVAL-WBC2TX50 User Manual

Wireless power transmitter evaluation board
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STEVAL-WBC2TX50 wireless power transmitter evaluation board
Introduction
The
STEVAL-WBC2TX50
evaluation board, based on the STWBC2 integrated circuit (IC), is designed for wireless power
transmitter applications and allows its user to quickly start their 5 W Qi BPP, 15 W Qi EPP or 50 W STSC wireless charging
projects.
The STWBC2 wireless transmitter IC can deliver the following power transfer levels of inductive wireless power technology:
•
Up to 5 W charging power compatible with Qi 1.3 Baseline Power Profile (BPP)
•
Up to 15 W charging power compatible with Qi 1.3 Extended Power Profile (EPP)
•
Up to 50 W charging power using the STSC Profile
The BPP and EPP are specified by the Wireless Power Consortium's Qi specification.
The evaluation board is designed to operate with 5-20 V input voltage or with a USB PD power adapter.
Two interfaces are open to the user: UART for monitoring and control via
and SWD JTAG for direct NVM access. Both interfaces are accessible via the STLINK-V3MINIE bridge.
The
STEVAL-WBC2TX50
includes several safety mechanisms providing over temperature (OTP), overcurrent (OCP),
overpower (OPP), overvoltage (OVP) and Vin drop protections as well as foreign object detection (FOD) for reliable designs.
UM3231 - Rev 1 - February 2024
For further information contact your local STMicroelectronics sales office.
Figure 1.
STEVAL-WBC2TX50 evaluation board
STSW-WBC2STUDIO
graphical user interface (GUI)
UM3231
User manual
www.st.com

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Summary of Contents for ST STEVAL-WBC2TX50

  • Page 1: Figure 1. Steval-Wbc2Tx50 Evaluation Board

    UM3231 User manual STEVAL-WBC2TX50 wireless power transmitter evaluation board Introduction STEVAL-WBC2TX50 evaluation board, based on the STWBC2 integrated circuit (IC), is designed for wireless power transmitter applications and allows its user to quickly start their 5 W Qi BPP, 15 W Qi EPP or 50 W STSC wireless charging projects.

  • Page 2: Getting Started

    UM3231 Getting started Getting started To get started with the STEVAL-WBC2TX50, you need the following items to use the reference design kit: • Evaluation kit components: – STEVAL-WBC2TX50 board • Additional hardware: – USB PD adapter or power supply ◦...

  • Page 3: Reference Design Specifications

    UM3231 Reference design specifications Reference design specifications The target specifications of the STEVAL-WBC2TX50 evaluation board are given in the following table. Table 1. Reference design specifications Parameter Description Qi compatibility Qi 1.3 compatible Tx application PCB area 68 mm x 53 mm Tx coil specifications Inductance 10 µH, DCR 50 mΩ, @ 100 kHz, dimensions 53 mm x 53 mm x 4.5 mm...

  • Page 4: Overview Of The Board

    UM3231 Overview of the board Overview of the board STEVAL-WBC2TX50 evaluation board is optimized for performance. The board features: • STWBC2 wireless power transmitter chip • Optimized BOM and PCB space • On board full bridge inverter • 32-bit, 64 MHz Arm® Cortex® M0+ microcontroller with 32 KB SRAM •...
  • Page 5 UM3231 Overview of the board • For runtime firmware updates, configuration, and diagnostics, the UART is sufficient. If the FW is corrupted (for example because of power loss during firmware load), the UART is not available and SWD interface needs to be used. The SWD interface also provides higher transfer speed than UART. These two interfaces are intended for development and debugging.

  • Page 6: Test Points

    UM3231 Overview of the board Test points STEVAL-WBC2TX50 features several connectors and test points to provide easy access to key signals. Figure 3. Test points Table 2. Test points Connector/test point Name Description TP101 Input voltage (power pins) TP105 Ground input power, common ground...

  • Page 7: Basic Operating Modes

    Status LEDs There are two LEDs present on the STEVAL-WBC2TX50 board. The red and green LED indicates the device status as per the following table: For more details about the device status, use the event box of the GUI.

  • Page 8: Device Description And Operation

    UM3231 Device description and operation Device description and operation System block diagram Figure 4. Block diagram Power inverter The power inverter is a key block in charge of converting the DC bridge voltage into an AC power signal for the transmitting coil.

  • Page 9: Bridge Voltage Monitor

    The 3.3 V output is generated from VDD. The 3.3 V is used to power the MCU, analog low-voltage circuits, and level shifters of STWBC2. The maximum output current is 150 mA (user application + STEVAL-WBC2TX50 consumption). External LDO capacitors should be placed as close to the IC as possible.

  • Page 10: Power Up Sequence

    Chip reset The NRESET signal on the STEVAL-WBC2TX50 board is connected to reset pins of STWBC2 and STSAFE chips. Pulling this signal down forces both chips into reset. When released, this signal is pulled up to 3.3 V via a 10 kΩ...

  • Page 11: Voltage Drop

    The STWBC2 can monitor voltage from up to two NTC thermistors. These NTCs can monitor critical points of the board - the H-bridge transistors, DC-DC, main Tx coil, etc. STEVAL-WBC2TX50 features two NTCs: one placed near the DC-DC capacitors and the second one close to the H-bridge.

  • Page 12: Comparing To Reference Q Factor

    UM3231 Device description and operation The presence detection uses the same hardware and a similar principle as Section 4.8.7: QFOD. 4.9.2 Comparing to reference Q factor According to the Qi specification, an EPP Rx must provide its reference Q-factor and resonant frequency to the Tx during the negotiation phase.

  • Page 13: Figure 5. Difference Between Bpp And Epp Power Transfer Startup

    UM3231 Device description and operation Figure 5. Difference between BPP and EPP power transfer startup • Baseline Protocol: the original protocol introduced in version 1.0 of the Qi Power Class 0 specification, which uses Power Receiver to Power Transmitter communications only. •...

  • Page 14: Wireless Power Interface

    The processing of ASK packets and possible FSK reply are done autonomously. Any proprietary communication above the scope of Authentication or STSC that are implemented in FW needs to be implemented in the custom FW and ST support team needs to be contacted for such support. 4.12.1 ASK communication A state (either High or Low) is characterized by the amplitude being constant (with a certain variation Δ) for at...

  • Page 15: Figure 6. Ask Modulation

    UM3231 Device description and operation Figure 6. ASK modulation Figure 7. ASK timing The power receiver uses a differential biphase encoding scheme to modulate the data bits onto the power signal. The STWBC2 monitors ring voltage, current, and phase, filters out the carrier wave, and demodulates the signal. The communication itself is carried out via packets.

  • Page 16: Fsk Communication

    UM3231 Device description and operation To transmit a single byte of data, the power receiver must send an 11-bit sequence. This sequence consists of a START bit (ZERO), the 8 data bits of the byte (LSB first), a parity bit and a STOP bit (ONE). The parity is odd, meaning an even number of ONE bits in the data byte results in the parity bit being equal to ONE, while an odd number of ONE bits in the data byte results in the parity bit being equal to ZERO.

  • Page 17: Most Common Qi Communication Packets

    UM3231 Device description and operation Figure 10. Format of the three defined messages For a more detailed explanation refer to the Qi specification, section Power Transmitter to Power Receiver communications interface. 4.12.3 Most common Qi communication packets • Control error packet (CEP) provides feedback from the power receiver to the power transmitter about the amount of power required by the load.

  • Page 18: Stlink

    JTAG and SWD interfaces. It also provides a bootloader interface: UART, USB DFU, I²C, SPI, CAN. The SWD interface can be used to load the firmware binary into the device. STM32CubeProgrammer can be downloaded from www.st.com. UM3231 - Rev 1 page 18/84...

  • Page 19: Firmware Flash Programming

    UM3231 Device description and operation 4.14.1 Firmware flash programming The latest firmware binary can be downloaded from STSW-WBC2FW. To load the firmware into STWBC2: Step 1. Run the STM32CubeProgrammer.exe Step 2. Select STLINK, set the parameters as shown in the picture and click [Connect] Figure 11.

  • Page 20: Uart

    UM3231 Device description and operation 4.15 UART STWBC2 is intended to be operated independently that is, without being interfaced with a host system. For development purposes, there might be a need to access the device for the runtime diagnostics and configuration. This is done primarily by the STSW-WBC2STUDIO software, which is described in...

  • Page 21: Table 4. Switch To Boot Mode

    UM3231 Device description and operation 4.15.2.1 Switch to boot mode The switching is done by sending a “BOOT” command over UART. This will stop the firmware and start the bootloader. This command is only applicable for devices not in bootloader mode. To distinguish devices in bootloader mode, the following Init and Get commands can be used.

  • Page 22: Table 7. Memory Erase Command

    UM3231 Device description and operation 4.15.2.4 Extended erase Will erase N+1 pages. The N and page number are both 16 bit. Does not operate with an address, but with page number. This command is applicable for the device in bootloader mode. Table 7.

  • Page 23: Bootloader And Boot Pin

    UM3231 Device description and operation 4.15.2.6 Calibration Two commands are sent: Switch to page 0 and Calibrate. This command is applicable for device not in bootloader mode. Table 9. Calibration command Command Switch page 0x70 0x00 Calibrate 0x77 0x35 0x07 4.15.3 Bootloader and boot pin The pin 49 SWCLK of STWBC2-HP shares the functionality of BOOT0 pin of STM32G071 core.

  • Page 24: The Qi Authentication Procedure

    UM3231 Device description and operation 4.16.2 The Qi authentication procedure The Qi authentication requires a secure element including two certificates and a digest: • A product unit certificate (or a leaf certificate) which is unique for each device. This certificate is signed by a Manufacturer CA private key.

  • Page 25: Stsafe-A110 Test Profile For Steval-Wbc2Tx50

    • The Manufacturer CA is the STM STSAFE-A TEST CA 91, which is a test manufacturer certificate owned by ST and signed by the WPCCA3. • The Product Unit Certificate signed by the STM STSAFE-A TEST CA 91 with a Qi RSID, unique for each sample.

  • Page 26: How To Acquire Official Stsafe-A110 Samples

    The customer sends ST the PTMC and the Qi ID provided by the WPC. Step 4. ST creates a CSR for the customer and sends it to the WPC to obtain the customer official Manufacturer CA certificate in return. Step 5.

  • Page 27: Graphical User Interface (Gui)

    Connecting STWBC2 to the GUI Step 1. Connect the STLINK-V3MINIE bridge to a PC by USB cable. Step 2. Connect the STEVAL-WBC2TX50 board, connector J203 to STLINK-V3MINIE bridge by a flat cable. Step 3. Power up the STEVAL-WBC2TX50. Step 4.

  • Page 28: Info Page

    EPP: power transfer is progress; the Qi Extended power profile (up to 15 W) has been negotiated. • STSC: the ST Super Charge protocol has been activated. Based on the Rx request, the input voltage can be increased to up to 20 V if operating from USB PD.

  • Page 29: Event Box

    UM3231 Graphical user interface (GUI) 5.2.2 Event box Figure 19. Event box Changes of device status and various events are shown in here. The events can be cleared by clicking on the [Clear] button. UM3231 - Rev 1 page 29/84...

  • Page 30: Table 11. Available Events

    UM3231 Graphical user interface (GUI) 5.2.2.1 Available events Table 11. Available events Event Meaning Consequence AFE_INIT_DONE The startup of STWBC2 AFE done. Device can begin its functions. The Tx does not support the guaranteed power requested by Rx. Also appears if Charging started, but with CHARGING_AT_REDUCED_RATE Tx switched to BPP only, but the Rx...
  • Page 31 UM3231 Graphical user interface (GUI) Event Meaning Consequence The Rx asked to restart power transfer EPT_RESTART_POWER_TRANSFER Return to ping phase. by EPT/rst packet. The Rx asked to stop power transfer by EPT_UNKNOWN EPT/null packet. The Rx does not find Return to ping phase. any of the above reasons appropriate The Rx asked to stop power transfer by Stop the power transfer.
  • Page 32 UM3231 Graphical user interface (GUI) Event Meaning Consequence Unable to send FSK packet from Tx to Rx. Possible reason might be the Rx Stop power transfer, return to FSK_PKT_ERROR messaging is too fast and Tx does not ping phase. have sufficient time to respond. Stop power transfer.

  • Page 33: Device Metrics

    UM3231 Graphical user interface (GUI) 5.2.3 Device metrics There are several metrics, which indicate the current status of the device and help to identify possible issues. Please note that some of the values cannot be updated if the device is not in power transfer mode. (Rx reported power) or in digital ping (bridge mode).
  • Page 34 Voltage level measured on VIN pin of STWBC2. 5.2.3.9 Coil temperature The temperature measured by the onboard NTC. In case of the STEVAL-WBC2TX50 evaluation board, the NTC is placed next to the electrolytic capacitors of the DC-DC boost circuit. 5.2.3.10 Current state The device state machine related to power transfer status.

  • Page 35: Tx Information

    UM3231 Graphical user interface (GUI) 5.2.3.14 Bridge mode Indicates whether half-bridge or full-bridge mode is used for power transfer. 5.2.3.15 Message rate The rate at which the power transmitter receives messages from the power receiver. A higher rate usually indicates intense regulation or proprietary communication. Higher rate will also be observed during power transfer initiation.

  • Page 36: Charts Page

    UM3231 Graphical user interface (GUI) Charts page Allows the user to monitor key operational parameters. Figure 24. Example of captured charts The maximum buffer size (time span) available is 50 seconds. The data is sampled twice per second and up to 4 different charts can be displayed at a time.

  • Page 37: Configuration File

    UM3231 Graphical user interface (GUI) 5.4.1 Configuration file The prepared configuration can be saved to a file in the PC, or the existing file can be loaded to the GUI. The mentioned operations can be performed by these two buttons. The standard windows dialog for operations with files will then appear.
  • Page 38 UM3231 Graphical user interface (GUI) Parameter Meaning and notes Threshold for before ping QFOD. If Qfactor is very low, we suspect FO and do not continue with ping to protect the device and power source. The presence of such FO can cause a large current peak during digital ping.
  • Page 39 DisableFeature_2 0x0001 - BIT_DISABLEFEATURE_CHIP_OVER_TEMPERATURE 0x0002 - BIT_DISABLEFEATURE_RING_V_LIMITER 0x0004 - APP_EXT_CFG_FORCE_VIN_12V 0x0040 - APP_EXT_CFG_DISABLE_DCDC_SHORT OptionBits_1 0x1000 - APP_EXT_CFG_ENABLE_CUST_LED 0x2000 - APP_EXT_CFG_ENABLE_DYN_OVP_PLUS 1. The usage of the default value is recommended, unless discussed with ST support. UM3231 - Rev 1 page 39/84...

  • Page 40: Read/Write To Device

    The [Save] button can be used to save the traces into a csv file. Make sure to always save traces when contacting your ST support. The traces buffer capacity is 2000 recordings and is reset upon reaching the limit. If the [Partial Back Up] checkbox is enabled, the traces are saved into a file before being deleted.

  • Page 41: Fw Page

    Obtaining the firmware update file Firmware update file can be found on the ST website or obtained from your local ST support. When the firmware is loaded into the chip, the configuration can be changed and saved to the chip. The new file can be then created by the [Read All] button.

  • Page 42: Recommended Flow Of Prototyping And Production

    Recommended flow of generating and usage of the FW+Configuration file for mass production. Figure 28. Test points Protection tuning The STEVAL-WBC2TX50 firmware features several tunable protections. The tuning is done with the support from GUI. A strategy for tuning these protections is described in the separate application note. 5.7.1 Foreign object detection Power balance FOD compares power transmitted to power received, reported to the Tx by Rx via RPP packets.

  • Page 43: Dynamic Ovp

    UM3231 Graphical user interface (GUI) 5.7.3 Dynamic OVP Protects the power receiver from abrupt rises of the VRECT voltage. It predicts the rises based on the operational parameters of the transmitter (ring, bridge voltage, current). 5.7.4 Current Drop OVP Protects the power receiver from overvoltage caused by drops of load. The detection is based on Tx measured bridge current drop amplitude.

  • Page 44: Steval-Wbc2Tx50 Description

    STEVAL-WBC2TX50 description Schematic diagrams Figure 29. STEVAL-WBC2TX50 circuit schematic (1 of 6) R103 D102 UART_RX R102 10 R DP 2 DP 1 US B_DP R101 10 R US B_CC1 J 100 US B_DM R100 632723300011 UART_TX ECMF02-2AMX6 R107 TX+1 RX+1...

  • Page 45: Figure 30. Steval-Wbc2Tx50 Circuit Schematic (2 Of 6)

    Figure 30. STEVAL-WBC2TX50 circuit schematic (2 of 6) VBUCK VREF Voltage doubler C207 C238 C235 D200 C201 R235 100 R 4.7UF 100NF RB541VM-40 J 201 4.7UF QF_DRV QF_DRIVER 6.3V 6.3V 6.3V VDCDC R227 R228 I2C_S CL C202 I2C_S DA 470NF 4.7 K...

  • Page 46: Figure 31. Steval-Wbc2Tx50 Circuit Schematic (3 Of 6)

    Figure 31. STEVAL-WBC2TX50 circuit schematic (3 of 6) Q300 S TL20N6F7 C312 R301 GD_HS 1 R303 C315 10NF 10 K R306 R307 10 R 10 R VDCDC S W_HS 1 R300 0.010R/2W L300 3.3uH C300 C301 C317 Q301 C302 C314...

  • Page 47: Figure 32. Steval-Wbc2Tx50 Circuit Schematic (4 Of 6)

    Figure 32. STEVAL-WBC2TX50 circuit schematic (4 of 6) VDCDC DCDC SHORT 60V_0.023R_42A_P -Channel S TL42P 6LLF6 Q404 R411 30 K Q405 L400 DCDC_S HORT P DTC114EU,135 R410 D400 30 K VBRIDGE C401 C402 C410 C411 C400 C403 C404 C405 10UF...

  • Page 48: Figure 34. Steval-Wbc2Tx50 Circuit Schematic (6 Of 6)

    Figure 34. STEVAL-WBC2TX50 circuit schematic (6 of 6) Parts PCB ASSEMBLY Parts COIL ASSEMBLY M1000 M1001 M1002 M1003 SCREW M2*15 SCREW M2*15 SCREW M2*15 SCREW M2*15 M1011 M1018 M1010 M1017 M1012 SCREW M2*10 SCREW M2*10 SCREW M2*10 SCREW M2*10 SPACER_100X60X3_MP_TOP...

  • Page 49: Bill Of Materials (Bom)

    UM3231 STEVAL-WBC2TX50 description Bill of materials (BOM) Table 14. STEVAL-WBC2TX50 BOM Item Ref. Value Package Description Manuf. Part number C100, C203, C241, CAPACITOR SMD 0402 100nF C242, 100 nF 0402 Wurth 885012205086 50V X7R 10% C243, C302, C309 C101, C102,...
  • Page 50 UM3231 STEVAL-WBC2TX50 description Item Ref. Value Package Description Manuf. Part number CAPACITOR SMD 0402 1nF 100V C220 1 nF 0402 Wurth 885012205080 X7R 10% C221, N.A. 0402 Not populated capacitor SMD 0402 N.A. N.A. C222 CAPACITOR SMD 0402 33pF 50V...
  • Page 51 UM3231 STEVAL-WBC2TX50 description Item Ref. Value Package Description Manuf. Part number CON_JACK_21MM- WURTH J101 POWER JACK DC POWER JACK DC 694106301002 PJ-002A ELEKTRONIK J201 4-pin 1X4P_2.54mm Header, 1X4P, 2.54mm Harwin M20-9770446 FTSH-107-01-L-DV- CON_FTSH-107-01- J203 SMD_HEADER_2x7_P1.27 SAMTEC FTSH-107-01-L-DV-K-A L-DV-K-A L200, 10 µH L2.5_W2.0_H1.2...
  • Page 52 UM3231 STEVAL-WBC2TX50 description Item Ref. Value Package Description Manuf. Part number R206, 47 K 0402 NTC SMD 0402 47k 1% MURATA NCP15WB473F03RC R211 RESISTOR SMD 100 R207 100 K 0402 YAGEO RC0402FR-07100KL K_1%_0402_1/16W R212, RESISTOR SMD 2.2 R225, 2.2 R...
  • Page 53 UM3231 STEVAL-WBC2TX50 description Item Ref. Value Package Description Manuf. Part number 38V, 3 A step-down switching U500 L7986ATR HSOP8 L7986ATR regulator Y200 N.A. L2.0_W1.6 Not populated SMD crystal N.A. N.A. Solder WURTH MP-A2 Coil, MP-A2 760308103102 TP400- ELEKTRONIK TP401 R100,...

  • Page 54: Component Assembly

    UM3231 STEVAL-WBC2TX50 description Component assembly Figure 35. Component assembly UM3231 - Rev 1 page 54/84...

  • Page 55: Steval-Wbc2Tx50 Pcb Layout

    UM3231 STEVAL-WBC2TX50 description STEVAL-WBC2TX50 PCB layout Figure 36. PCB top layer Figure 37. PCB inner1 layer UM3231 - Rev 1 page 55/84...

  • Page 56: Figure 38. Pcb Inner2 Layer

    UM3231 STEVAL-WBC2TX50 description Figure 38. PCB inner2 layer Figure 39. PCB bottom layer UM3231 - Rev 1 page 56/84...

  • Page 57: Stwbc2 Default Configuration

    UM3231 STEVAL-WBC2TX50 description STWBC2 default configuration Table 15. Basic parameters Parameter Value Transmitter topology MPA2 Tx bridge mode Half (BPP)/Full (EPP, STSC) Minimum duty cycle Maximum duty cycle Minimum operating frequency 110 kHz Maximum operating frequency 148 kHz Ping duty cycle...

  • Page 58: Typical Performance Characteristics

    UM3231 STEVAL-WBC2TX50 description Typical performance characteristics 6.6.1 Power-up waveforms The following figure shows a typical power-up sequence when the device is supplied from USB PD. When the digital core is awake and all checks are done, the device switches the USB PD to a 5 V mode and its Vbuck into a 3.6 V mode to lower the power consumption.

  • Page 59: Analog And Digital Ping

    UM3231 STEVAL-WBC2TX50 description 6.6.2 Analog and digital ping The following figure shows analog ping (presence detection) on AC1. Then a Q factor measurement follows. After that, the USB PD raises its voltage from 5 V to 9 V, the Vbuck is raised to 5 V and finally a digital ping is executed.

  • Page 60: Startup Of Epp

    The measurement was done for 20 V input voltage and 20 V output voltage. The test setup consisted of: • Rohde&Schwarz HMP4040 power supply • STEVAL-WBC2TX50 as the transmitter • STEVAL-WLC98RX as the receiver • Electronic load in CC mode, model Itech IT8512...

  • Page 61: Figure 43. Setup For Offset Test

    UM3231 STEVAL-WBC2TX50 description Figure 43. Setup for offset test The maximum efficiency achieved with this setup was 85.25%. Efficiency curves for various misalignments in the X and Y axis are shown in the figures below: Figure 44. X-axis offset impact on efficiency...

  • Page 62: Efficiency And Spatial Freedom In The Z-Axis

    Z-axis distance between the coils, also known as charging gap, is an additional parameter that significantly affects charging performance. The STEVAL-WBC2TX50 was therefore also tested at various charging gap distances. The same setup was used as for the previous test. Efficiency curves for various misalignments in the Z-axis are shown in the figure below: Figure 46.

  • Page 63: Thermal Performance

    UM3231 STEVAL-WBC2TX50 description 6.6.6 Thermal performance Thermal performance of the board with a 50 W load (20 V/2,5 A on the Rx side) after 5 minutes of continuous operation. The coils are centered with 3 mm z-distance. Figure 47. Thermal performance...

  • Page 64: Designing A Wireless Power Transmitter Based On Steval-Wbc2Tx50

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board Designing a wireless power transmitter based on STEVAL- WBC2TX50 evaluation board We strongly recommend limiting modifications of the schematic to a minimum, as the board schematic and BOM were designed both for performance and cost. Caution should also be paid when modifying the layout of the board.

  • Page 65: Ground Plane On Layer 4

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board 7.2.2 Ground plane on Layer 4 The ground plane integrity on layer 4 shall be maximized as much as possible. Therefore, try to limit the number of tracks routed on this layer.

  • Page 66: Board Input Layout

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board 7.2.3 Board input layout USB Type-C® and barrel jack connectors are placed closely together. The TVS diodes and the input capacitors are placed close to the input connectors and the layer 1 ground plane is connected to the other ground planes through multiple vias.

  • Page 67: Vin, Vbuck, And Vdoubler

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board 7.2.4 VIN, Vbuck, and Vdoubler Use wider tracks for Vin, Vbuck and Vdoubler. The input capacitors shall be as close to the IC as possible. Place the DC-DC buck components close to STWBC2 to minimize area of the resulting current loops.

  • Page 68: Figure 52. Green: Dc-Dc Buck Placement. Yellow: Capacitors Close To Stwbc2 Ic

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board Figure 52. Green: DC-DC buck placement. Yellow: Capacitors close to STWBC2 IC. UM3231 - Rev 1 page 68/84...

  • Page 69: Vin Isns Routing

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board 7.2.5 VIN ISNS routing The input current is sensed on R300 and the ISNS_N and ISNS_P tracks are routed closely together for an accurate measurement. Figure 53. VIN ISNS routing...

  • Page 70: Dc-Dc Boost Circuit

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board 7.2.6 DC-DC boost circuit The DC-DC boost circuit is placed close to the input of the board to minimize the current loops. Q300 and Q301 MOSFETs are placed close to L300 for the same reason. The tracks connecting R300 to the input and to L300 are wide to accommodate for the input current.

  • Page 71: Bridge Isns Routing

    UM3231 Designing a wireless power transmitter based on STEVAL-WBC2TX50 evaluation board 7.2.8 Bridge ISNS routing Bridge ISNS_P and ISNS_N tracks routed closely together for an accurate measurement. Figure 56. Bridge ISNS routing 7.2.9 Gate drivers routing Bridge gate drivers routed by pair from STWBC2 to bridge MOSFETs.

  • Page 72: Board Versions

    UM3231 Board versions Board versions Table 16. STEVAL-WBC2TX50 versions Finished good Schematic diagrams Bill of materials STEVAL$WBC2TX50A STEVAL$WBC2TX50A schematic diagrams STEVAL$WBC2TX50A bill of materials 1. This code identifies the STEVAL-WBC2TX50 evaluation board first version. UM3231 - Rev 1 page 72/84...

  • Page 73: Regulatory Compliance Information

    Conformity. Notice for United Kingdom The kit STEVAL-WBC2TX50 is in compliance with the UK Radio Equipment Regulations 2017 (UK SI 2017 No. 1206 and amendments) and with the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Regulations 2012 (UK SI 2012 No. 3032 and amendments). Applied standards are listed in the UK Declaration of Conformity.

  • Page 74: References

    UM3231 References References More information about Qi specification can be found on the WPC website Qi Mobile Comp. UM3231 - Rev 1 page 74/84...

  • Page 75: Acronyms And Definition

    UM3231 Acronyms and definition Acronyms and definition Table 17. List of acronyms Acronym Explanation Wireless Power Consortium Certificate authority PTMC Power Transmitter Manufacturer Certificate RSID Revocation sequential identifier Public key infrastructure Certificate signing request Hardware security module Rx, Rx Wireless power receiver Tx, Tx Wireless power transmitter The Qi specification, published by the Wireless Power Consortium...

  • Page 76: Revision History

    UM3231 Revision history Table 18. Document revision history Date Version Changes 23-Feb-2024 Initial release. UM3231 - Rev 1 page 76/84...

  • Page 77: Table Of Contents

    UM3231 Contents Contents Getting started ..............2 Reference design specifications .
  • Page 78 The Qi authentication procedure ..........24 4.16.3 STSAFE-A110 test profile for STEVAL-WBC2TX50 ......25 4.16.4 How to acquire official STSAFE-A110 samples .
  • Page 79 STEVAL-WBC2TX50 description ........
  • Page 80 UM3231 Contents 7.2.9 Gate drivers routing............71 7.2.10 DC-DC short circuit .
  • Page 81 STEVAL-WBC2TX50 circuit schematic (1 of 6) ........
  • Page 82 UM3231 List of figures Figure 54. DC-DC boost circuit routing ............70 Figure 55.
  • Page 83 STEVAL-WBC2TX50 versions ........
  • Page 84 ST’s terms and conditions of sale in place at the time of order acknowledgment. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of purchasers’...

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