ST STEVAL-ISB042V1 User manual

Introduction
The STEVAL-ISB042V1 is a 15-watt Qi and 5-watt Airfuel inductive (former PMA) wireless power receiver evaluation board
based on the STWLC33 wireless power receiver solution for the WPC/Airfuel mobile device with dual mode coil.
The board lets you evaluate the STWLC33 capabilities as a Qi/Airfuel inductive receiver as well as its ability to power another Qi
receiver.
The solution is certified in accordance with the extended power profile Qi v1.2 and Airfuel SR1 standard.
The STWLC33 IC is powered by a dual mode Rx coil attached to a 1.5 mm thick plastic fixture.
The STWLC firmware offers users the flexibility to modify parameters and settings to ensure proper integration of the STWLC33
device with the final application.
The layout is based on a cost-effective 4-layer PCB.
Figure 1. STEVAL-ISB042V1 evaluation board
Getting started with the dual mode wireless power evaluation board for Qi and Air-
fuel inductive receiver and Qi-based transmitter with STWLC33
UM2289
User manual
UM2289 - Rev 2 - December 2017
For further information contact your local STMicroelectronics sales office.
www.st.com/

1 Getting started
1.1 Board configuration and test points
• P3 solder bridge:
– open = I²C bus and INT pin pull-up voltage provided externally via J5 header
– shorted = I²C bus and INT pin pull-up voltage provided by STWLC33 (do not connect any load/source
to J5 header)
• P9 solder bridge:
– open = USB port acts as unknown (D+/D- floating)
– shorted = USB port acts as a dedicated charging port (shorted D+/D-)
• J3 testpoint header:
– VRECT rectified voltage
• J4 testpoint header:
– selectable user functions (GPIO0, GPIO1, GPIO2, GPIO4)
– GPIO3 – do not connect any load during startup
– INT – open drain interrupt output (active low)
– EN – enable input (active low), pull on-board R4 down
1.2 Receiver mode
The easiest way to test the STEVAL-ISB042V1 evaluation board in receiver mode is to connect the load to J2
header or, optionally, to J1 USB connector and place it on the transmitter surface.
J1 and J2 connectors are essentially different connectors for the same output node.
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Getting started
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Figure 2. STEVAL-ISB042V1 evaluation board: receiver mode
D6 indication LED lights up when the receiver enters the Power Transfer phase.
1.3 Transmitter mode
To test the board in Tx mode, you must provide a 5 V power supply to the J2 header (ensure STWLC33 is not
operating in Rx mode power transfer) and switch STWLC33 to Tx mode over I²C interface (J8 header).
Procedure Step 1. Connect the bundled USB to the I²C bridge.
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Transmitter mode
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Figure 3. STEVAL-ISB042V1 evaluation board: transmitter mode
Step 2. Use the PC GUI application.
Step 3. Connect the I²C bridge.
Step 4. Switch to TX mode tab.
Step 5. Click Load binary image button.
Step 6. Select the GUI STWLC33_TxMode_RAM_binary.bin file.
Figure 4. STEVAL-ISB042V1 GUI Tx mode tab
Step 7. Verify the result by checking the operation mode.
If the label indicates Transmitter mode, the kit is ready and a receiver can be placed on the coil sur-
face.
Note: The coil used in the kit is a Qi/PMA receiver coil. Using this coil for transmitter mode leads to many compromis-
es and not all Qi certified receivers will work with this kit. For the Tx mode evaluation we recommend to use the
STEVAL-ISB043V1 wearable receiver kit as a receiver.
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Transmitter mode
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Figure 5. STEVAL-ISB042V1 GUI operation mode
1.4 STWLC33 NVM configuration
The STWLC33 NVM configuration is the same default configuration as in STWLC33 samples (see STWLC33 da-
tasheet).
1.4.1 Board overview
The STEVAL-ISB042V1 evaluation board default configuration has good performance.
The board features:
• STWLC33 evaluation board with Würth Elektronik dual mode coil (760308102207)
• Qi 1.2 compliant, supporting extended power profile: up to 15 W/10 V maximum output power
• Backward compatible with Qi baseline power profile: up to 5 W/5 V maximum output power
• PMA-SR1 (AirFuel inductive) compliant: 5 W/5.6 V maximum output power
• Transmitter function based on Qi protocol to charge wearable devices using the same Rx coil (up to 3 W
power)
• Total system efficiency up to 80%
• Configurable GPIOs for status indication
• I²C interface for communication with the host system
• Foreign object detection (FOD)
• Complete kit (IC, firmware)
• RoHS compliant
1.5 GUI: I²C register access
Most fields in the GUI application correspond to a single I²C register.(For further details, see STWLC33 datasheet
on www.st.com.)
Many registers are accessible in receiver or transmitter mode only.
Before accessing the registers, you must check the actual operation mode in the Sys_Op_Mode register.
1.5.1 Rx mode registers
The Registers tab contains three sub-tabs related to Rx mode I²C register controls.
Through the Interrupt registers sub-tab, you can monitor the following registers:
• Status_Rx
• INT_Rx
• INT_Enable_Rx
• INT_Clear_Rx
The GUI directly reads or writes the target register.
The Interrupt clear button first writes the INT_Clear_Rx register and then writes 1 in the Clr_Int bit in Com
register.
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STWLC33 NVM configuration
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Figure 6. GUI Rx mode: Interrupt registers sub-tab
The Setup and measurement registers sub-tab controls registers and measurement values.
VOUT_set or ILIM_set modifications are immediate.
The default values are loaded automatically from NVM after wireless operating standard detection.
Important: Refer to 2 Configuration guidelines before changing the values.
The Power transfer termination consists of two steps:
• writing the EPT register;
• writing 1 in the S_EPT bit in Com register.
AD conversion results provide immediate VRECT and VOUT voltages as well as die temperature and output cur-
rent during power transfer.
RXID and PRMC_ID registers become active after wireless standard detection and provide an easy-to-read self-
ID (either Qi ID or PMA ID).
If the STWLC33 receiver is placed on a PMA pad that supports advertising, the advertising ID is captured and can
be read through PMA ADV registers.
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GUI: I²C register access
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Figure 7. GUI Rx mode: Setup and measurement registers sub-tab
The Qi – Proprietary packets sub-tab allows sending any Qi packet and (in Qi 1.2 only) receive the response
from the transmitter (both pattern type or data type responses are supported).
Figure 8. GUI Rx mode: Qi – Proprietary packets sub-tab
1.5.2 Tx mode registers
After entering the mode as described in 1.3 Transmitter mode, the TX mode tab lets you monitor the following
registers:
• Status_Tx
• INT_Tx
• INT_Enable_Tx
• INT_Clear_Tx
The GUI directly reads or writes the target register.
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GUI: I²C register access
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The Interrupt clear button first writes the INT_Clear_Tx register and then writes 1 in the Clr_Int bit in Com reg-
ister.
Tx frequency setup allows modifying the regulation control algorithm minimum and maximum frequency and the
starting ping frequency.
Note: The optimal ping frequency for the STEVAL-ISB042V1 evaluation board is approximately 130 kHz.
ASK demodulation thresholds parameter defines the ASK receiver sensitivity.
Figure 9. GUI Rx mode: TX mode tab
1.6 GUI: NVM configuration access
1.6.1 Qi NVM configuration
The Qi configuration tab contains manufacturer and device identifiers sent over the Qi protocol.
The tab contains also default values for the VOUT voltage, Input current limit and Interrupt enable registers
which can be configured separately for baseline power profile (BPP) operation and for extended power profile
(EPP). BPP values are loaded in the registers and subsequently updated if EPP is negotiated.
STWLC33 automatically terminates the power transfer if the load is below a certain threshold for a certain period
of time. By default, this feature is eliminated by setting the lowest possible current and the longest possible time.
Note: Qi specification does not require this feature.
To maintain the Qi foreign object detection feature accurate, you must provide the correct values representing the
coil parameters and the mechanical setup.
The evaluation kit contains components with the correct values to be used.
But, if, for example, the coil is replaced by another type of coil, you must update the following parameters:
•FOD_A
•FOD_B (different values for BPP and EPP)
•FOD_C (same value for BPP and EPP)
•Reference quality factor (for EPP only)
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GUI: NVM configuration access
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Figure 10. GUI: Qi configuration tab
1.6.2 PMA NVM configuration
The PMA configuration tab contains the RXID identifier sent over the PMA protocol.
The tab contains also default values for the VOUT voltage, Input current limit and Interrupt enable registers.
The PMA specification requires that the receiver automatically terminates the power transfer if the load is below a
certain threshold for a certain period of time.
If the power transfer termination is controlled by the host system, the STWLC33 feature can be eliminated (by
setting zero current and maximum possible time).
Figure 11. GUI: PMA configuration tab
1.6.3 Platform NVM configuration
This tab allows assigning GPIO functions related to Rx mode only.
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GUI: NVM configuration access
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In Tx mode, all the pins are inputs with no function.
In the STEVAL-ISB042V1 evaluation board, the LED diode (D6) is controlled by GPIO2 pin.
Figure 12. GUI: platform configuration tab
1.6.4 Generic load/save NVM access
The NVM tab allows the backup of the current NVM configuration into a file or loading a new one from a file.
Figure 13. GUI: NVM tab
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GUI: NVM configuration access
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2 Configuration guidelines
2.1 Changing VOUT voltage: constraints
The power LDO supports setting VOUT from 3.5 to 12.5 V; but, selecting an appropriate VOUT value is more
complex and involves other aspects in the system, like:
1. OVP and margin for modulation (especially when using VOUT higher than 9 V): the first line OVP protec-
tion is the pre-clamp with fixed trigger at 13.5 V on VRECT node. During modulation (packet data sent from
Rx to Tx), the voltage on VRECT rises on the basis of conditions like Tx/Rx coil parameters, loading current,
VOUT voltage and so on. The VOUT setting must be always low enough to maintain VRECT during modula-
tion under the pre-clamp level. The safe VOUT voltage for the STEVAL-ISB042V1 evaluation board is 10 V.
The user should not set a higher value unless previously verified (via an oscilloscope) that the VRECT mod-
ulation has enough margin with respect to the pre-clamp threshold.
2. Tx coil voltage and Tx/Rx coil ratio: the whole system can be compared to a transformer where the coil
ratio defines the transformation ratio. The transmitter circuits and the Tx coil are designed to operate within
the expected optimal range in which the Rx coil and VOUT voltage should fit. If the configured VOUT voltage
is too high or too low, it shifts the whole system out of the optimal range. The right VOUT voltage for the
STEVAL-ISB042V1 evaluation board is roughly 4 to 5.5 V with 5 W transmitters and 8 to 10 V with 15 W
transmitters. Using a different output voltage may require a different Rx coil and input resonant circuit capac-
itors.
2.2 Input current limit
The power LDO is able to limit the output current. This limitation starts softly reducing the VOUT voltage even
before reaching the limit.
2.3 Minimal load
All wireless systems are designed to transfer power. If power is not being transferred, it becomes hard to maintain
Rx-to-Tx communication.
STWLC33 is equipped with a dummyload circuit that increases the load by consuming the power when no output
load is present. Due to heat dissipation the dummy consumption is limited to tens of milliamps.
Even if this should be enough to maintain communication with most transmitters, it is recommended to always
apply at least 100 mA.
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Configuration guidelines
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3 Performance charts
3.1 Baseline power profile (BPP) Rx mode performance
The STEVAL-ISB042V1 evaluation board performance in BPP has been evaluated through a Qi 1.2 BPP certified
transmitter. The overall system efficiency is above 78%.
Figure 14. STEVAL-ISB042V1 evaluation board performance: efficiency vs output power in BPP
The output voltage regulation is maintained under the threshold of a 1% difference from no load to full load.
Figure 15. STEVAL-ISB042V1 evaluation board performance: output voltage vs output power in BPP
3.2 Extended power profile (EPP) Rx mode performance
The STEVAL-ISB042V1 evaluation board performance in EPP has been evaluated through a Qi 1.2 EPP certified
transmitter capable of delivering up to 15 W at 10 V output voltage. The overall system efficiency is above 80%.
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Performance charts
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Figure 16. STEVAL-ISB042V1 evaluation board performance: efficiency vs load in EPP
0
10
20
30
40
50
60
70
80
90
1 3 5 7 11 13 15 17
Efficiency (%)
9
Rx Output power (W)
The output voltage regulation is maintained under the threshold of a 0.15% difference from no load to 10 W load
and 1.5% from no load to full load.
Figure 17. STEVAL-ISB042V1 evaluation board performance: output voltage vs output power in EPP
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0 2 4 6 10 12 14 16
Rx Output voltage (V)
8
Rx Output power (W)
3.3 TX mode performance
The STEVAL-ISB042V1 evaluation board performance in Tx mode has been evaluated through the STEVAL-
ISB043V1 wearable receiver. The overall system efficiency is above 70%.
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TX mode performance
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Figure 18. STEVAL-ISB042V1 evaluation board performance: efficiency vs output power in TX mode
0
10
20
30
40
50
60
70
80
0.500 1.000 1.500 2.000 2.500 3.000
Efficiency (%)
Rx Output Power (W)
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TX mode performance
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4 Schematic diagrams
Figure 19. STEVAL-ISB042V1 circuit schematic
100nF
CS1
2.2nF
CPAR
100nF
CS2
15nF
CBOOT2
15nF
CBOOT1
47nF
CM2
47nF
CM1
51k R4
VIOFLA SH
RESET/EN
INT
SCL
SDA
4k7
R1
4k7
R2
1k5
R3
12
D1
INT
100nF
C7
10µF
C3
V5V
PGND PGND
PGND
PGND
100nF
CS3
PGND
100nF
CS4
V5V
1.5nF
CFL T1
10µF
C4
1µF
C6
100nF
CCL 2
100nF
CCL 1
SCL SDA INT
PGND
RESET/EN
10µF
C1
10µF
C2
PGND
15R
RCL
22nF
CFL T2
10k
RFL T1
6.8nF
CFL T3
68k
RFL T2
620R
RFL T3
1 2
Q1
PGND
PGND
PGND 12V
D3 D Zener
PGND
1µF
C7a 100nF
C6a
100k
R6
100k
R7
PGND
10µF
C2a
100nF
C2b
SDA
SCL INT
GP0 GP1 GP2 GP3 GP4
1
2
J5
PGND
VIOFLA SH
1 2 3 4 5 6 7 8 9
10
11
12
J4 Header 12
PGND
V18
GP0 GP1 GP2 GP3 GP4
1
2
J3
PGND
VRECT
VRECT
1
2
J2
PGND
VOUT
VOUT
1
2
J6
PGND
1
2 3
T1
FDV303N
12
D6
1k5
R8
GP2
P
1uF / 6.3V
C14
VS2
BST2
BST1
1 2 3
J8 Header 3
PGND
SDA
SCL
1 2
3 4
5 6
7 8
J7 Header 4X2
PGND
Rx RNTC
PGND
V18 VS2
12V
D4
D Zener
1 2
P3
VIOFLA SHV18
GND
DP
DM
VBUS
SHIELD
J1
PGND
VOUT
12
P9
SCL
A3
SDA
B3
INT-N
C3
A2
B2
GPIO0
A4
GPIO1
B4
GPIO2
C4
GPIO3
A5
GPIO4
C5
/EN
B5
V5V
F1
GND
C1
PGND
I1
AGND
C6
BST2 G6
CMB B6
CM2 A6
AC2 H5
AC1 H1
CM1 A1
CMA B1
BST1 G1
VS1 G4
VS2 H4
HVOD C2
VRECT
OUT D1
V18 F6
PGNDPGNDPGNDPGNDPGND
OUTOUTOUTOUTOUT
VRECT
VRECT_S
VRECTVRECTVRECTVRECTVRECT
AC2AC2
AC1AC1
IO1 STWLC33
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Schematic diagrams
UM2289 - Rev 2 page 15/26

5 Bill of materials
Table 1. STEVAL-ISB042V1 bill of materials
Item Q.ty Ref. Part / Value Description Manufacturer Order code
1 1 IO1CSP 6x9, 400 μm
pitch
Wireless power
receiver
ST STWLC33
2 4 CS1, CS2, CS3,
CS4
100 nF/50 V, SMD
0402
Capacitors Murata GRM155R61H104KE19
3 1 CPAR 3.9 nF/50 V, SMD
0402
Capacitors Murata GRM155R71H392KA01
4 2 CBOOT1,
CBOOT2
15 nF/10 V, SMD
0402
Capacitors Murata GRM155R71H153KA12
5 2 CM1, CM2 47 nF/50 V, SMD
0402
Capacitors Murata GRM155R61H473KE19
6 2 CCL1, CCL2 100 nF/50 V, SMD
0402
Capacitor Murata GRM155R61H104KA
7 5 C1, C2, C2a, C3,
C4
10 μF/25 V, SMD
0805
Capacitors Murata GRM21BR61E106KA73L
8 1 C2b 100 nF/25 V, SMD
0201
Capacitor Samsung CL03A104KA3NNNC
9 1 C61 μF/6.3 V, SMD
0201
Capacitor Samsung CL03A105MQ3CSNH
10 2 C6a, C7100 nF/25 V, SMD
0402
Capacitors Murata GRM155R61E104KA87D
11 1 C7a 1 μF/10 V, SMD
0402
Capacitor Murata GRM155R61A105KE15
12 1 C14 1 μF/10 V, SMD
0603
Capacitor Murata GRM188R61A105MA
13 1 RCL 30 Ω, SMD 0805 Resistor Panasonic ERJ-P6WF30R0V
14 0 D1SMD 0402 Any Not assembled
15 2 D3, D4SOD882 Protection di-
ode
NXP PESD12VV1BL
16 0 D5, D2SOD882 Any Assembled short
17 1 D62 mA, SMD 0402 Red LED Any
18 1 Q1Schottky diode ST BAT48
19 1 RFLT1 10 kΩ±1%, SMD
0402
Resistor Any
20 1 RFLT2 68 kΩ±1%, SMD
0402
Resistor Any
21 1 RFLT3 620 Ω±1%, SMD
0402
Resistor Any
22 2 R1, R24k7 SMD 0402 Resistors Any
23 2 R3, R81k5, SMD 0402 Resistors Any
24 1 R451 kΩ, SMD 0402 Resistor Any
25 2 R6, R7100 kΩ, SMD
0402
Resistors Any
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Bill of materials
UM2289 - Rev 2 page 16/26

Item Q.ty Ref. Part / Value Description Manufacturer Order code
26 1 CFLT1 1.5 nF/50 V SMD
0402
Capacitor Murata GRM155R71H152KA01
27 1 CFLT2 22 nF/50 V SMD
0402
Capacitor Murata GRM155R71H223KA12
28 1 CFLT3 6.8 nF/50 V SMD
0402
Capacitor Murata GRM155R71H682KA88
29 1 RX30 kΩ SMD 0603 Resistor Any
30 0 RNTC SMD 0603 Resistor Any Not assembled
31 1 T1SOT23 Digital FET Fairchild FDV303
32 0 J1Any Not assembled
33 3 J2, J3, J5THT 2.54 mm
pitch
2-pin header Any
34 1 J4THT 2.54 mm
pitch
12-pin header Any
35 1 J6THT 2.54 mm
pitch
Coil wire con-
nection
Any
36 1 J7THT 2.54 mm
pitch
2x4-pin header Any
37 1 J8THT 2.54 mm
pitch
3-pin header Any
38 1 P3Soldered Solder option Any
39 1 P9Open Any Open
40 1 L 8 μH Coil connected
to J6
Wurth 760308102207
41 1 62x62x21 mm Plastic frame Any
42 1 3x10 mm 2x wood screw Any
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Bill of materials
UM2289 - Rev 2 page 17/26

6 Board layout
Figure 20. STEVAL-ISB042V1: top silkscreen and pads
Figure 21. STEVAL-ISB042V1: copper layer 1
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Board layout
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Figure 22. STEVAL-ISB042V1: copper layer 2
Figure 23. STEVAL-ISB042V1: copper layer 3
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Board layout
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Figure 24. STEVAL-ISB042V1: copper layer 4
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Board layout
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