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July 2020 AN5290 Rev 6 1/181
AN5290Application note
Minimal BOM for STM32WB Series microcontrollers
IntroductionSTM32WB Series microcontrollers are designed to
minimize the number of external components needed to ensure
optimized RF performance.
This document details the bill of materials (BOM) for Bluetooth®
Low-Energy applications.
The QFN48 package is used as a reference but the considerations
valid for it can easily be extended to other packages.
www.st.com
http://www.st.com
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Contents AN5290
2/18 AN5290 Rev 6
Contents
1 Design considerations . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . 51.1 SMPS and LDO
configurations . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . 5
1.2 LDO configuration for VDD > 3 V . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . 6
1.3 HSE trimming . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . 7
1.4 RF matching . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . 8
2 Schematics . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 9
3 Bill of materials . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 14
4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 16
5 Revision history . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . 17
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AN5290 List of tables
3
List of tables
Table 1. Bill of materials - Optimized solution with discrete
components . . . . . . . . . . . . . . . . . . . . . 14Table 2.
Bill of materials- Optimized solution with IPD . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . 15Table 3. Bill
of materials - Solution without SMPS . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . 15Table 4. Document
revision history . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . 17
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List of figures AN5290
4/18 AN5290 Rev 6
List of figures
Figure 1. Supply configurations . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . 5Figure 2. LDO configuration. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . 6Figure 3. Recommended schematic for the no SMPS
configurations (STM32WB55Vx). . . . . . . . . . . 6Figure 4. HSE
trimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7Figure 5. RF matching and external filters . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8Figure 6. Optimized solution with discrete components (STM32WBx5xx
products) . . . . . . . . . . . . . . 9Figure 7. Optimized solution
with discrete components (STM32WBx0xx products) . . . . . . . . . .
. . . 10Figure 8. Optimized solution with IPD (STM32WBx5xx
products) . . . . . . . . . . . . . . . . . . . . . . . . . . .
11Figure 9. Optimized solution with IPD (STM32WBx0xx products) . .
. . . . . . . . . . . . . . . . . . . . . . . . . 12Figure 10.
Solution without SMPS (STM32WBx5xx products) . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . 13
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AN5290 Rev 6 5/18
AN5290 Design considerations
17
1 Design considerations
1.1 SMPS and LDO configurationsThe STM32WB Series
microcontrollers are based on Arm®(a) cores.
The power management implemented on some of these devices (see
the datasheets available on www.st.com) embeds a powerful switched
mode power supply (SMPS) to improve power efficiency when the
supply voltage is higher than 2 V, otherwise the LDO configuration
is used. The two configurations are shown in Figure 1. See AN5246
“Usage of SMPS on STM32WB Series microcontrollers”, available on
www.st.com, for more details.
Figure 1. Supply configurations
To operate properly, the SMPS needs two inductors and two
capacitors. In the LDO configuration no external components are
needed. The detailed electrical schemes are shown in Section 2.
a. Arm is a registered trademark of Arm Limited (or its
subsidiaries) in the US and/or elsewhere.
MS41409V4
MR
LPR
RFR
SMPS
(not used)
MR
LPR
RFR
VDD
L1
C2
SMPS configuration LDO configuration
VDDVDDSMPS
VLXSMPS
VFBSMPS
SMPS
SMPS mode orBYPASS mode
VDDSMPS
VLXSMPS
VFBSMPS
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Design considerations AN5290
6/18 AN5290 Rev 6
1.2 LDO configuration for VDD > 3 VThis configuration applies
only to STM32WB55Vx devices with REV_ID = 0x2001 in register
DBGMCU_IDCODE (see RM0434, available on www.st.com).
An inductance and a resistor must be added in series between
VLXSMPS and VFBSMPS pins, as shown in Figure 2.
Figure 2. LDO configuration
The recommended values (see Figure 3) are: Inductance: 1.8 ± 0.1
nH, 6 GHz ± 15% self-resonance frequency, 1000 mA rated
current (e.g. Murata LQG15HS1N8B02) Resistor: 2.2 Ω, able to
support 1 W for 5 ns (e.g. Vishay D10/CRCW0402e3)
Figure 3. Recommended schematic for the no SMPS configurations
(STM32WB55Vx)
MS53566V1
SMPS(not used)
VDDSMPS
VLXSMPS
VFBSMPS
VDD
RFregulator
Mainregulator
LPregulator
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AN5290 Rev 6 7/18
AN5290 Design considerations
17
1.3 HSE trimmingSTM32WB MCUs use the HSE oscillator for the RF
clock generation, this component must be fine-tuned. Internal load
capacitors are used, removing the need for external parts, as shown
in Figure 4. See AN5042 “HSE trimming for RF applications using the
STM32WB Series”, available on www.st.com, for more details.
Figure 4. HSE trimming
STM32WBMSv47141V2
XTAL
OSC_IN
OSC_OUT
CapacitanceBank IN
CapacitanceBank OUT
Amplifierand
reshaping
Crystal oscillatorHSESHSEGMC[2:0]
HSETUNE[5:0]
HSE_CLK
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Design considerations AN5290
8/18 AN5290 Rev 6
1.4 RF matchingThere is a unique pin RX/TX for the RF and this
interface is single ended, thus eliminating the need for external
baluns. Furthermore, internal band pre-filtering helps to reduce
external components.
An external PI filter made-up by discrete components followed by
a ceramic filter is needed for, respectively, impedance matching
and harmonics rejection. Another matching network is required for
the antenna. To optimize the BOM and the performance stability,
these filters can be replaced by an internal passive device (IPD),
as shown in Figure 5.
Figure 5. RF matching and external filters
The RF performance strongly depends upon the PCB layout. AN5165
“Development of RF hardware using STM32WB microcontrollers”,
available on www.st.com, describes the precautions to be taken for
the layout of an RF board with the STM32WB.
Matching network
(50 ohms)
Ceramic filter
Antenna matching network
IPD
STM32WB
MS51761V1
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2 Schematics
Figure 6. Optimized solution with discrete components
(STM32WBx5xx products)
RF022
RF121
VDDRF23
U1A
STM32WBx5_QFN48
OSC_IN25
OSC_OUT24
PC14-OSC32_IN2
PC15-OSC32_OUT3
PH3-BOOT04
AT026
AT127
NRST7
U1C
STM32WBx5_QFN48
VDDA/VREF+8
VDD/VDDT20
VDD35
VDDUSB40
VBAT1
VDD48
VS
S(E
xPA
D)
49
U1D
STM32WBx5_QFN48
VDD
GND
GND
GNDGND
GND
NRST
C104.7uF
C13
4.7uF
GND
C415pF
GND
C315pF
X2NX2012_32K768
X1
NX2016_32M
GND
VDDUSB
VDD
GND
GND
GND
C8100nF
C9100nF
C12100nF
L1
IND_FCM1608KF-601T03
GNDGND
VDD
C1100nF
C2
100pF
L210uH
C11100nF
GND
VDDSMPS34
VSSSMPS32
VLXSMPS33
VFBSMPS31
VDDSMPS
VSSSMPS
VLXSMPS
VFBSMPS
U1B
STM32WBx5_QFN48
PA0-CK_IN9
PA110
PA211
PA312
PA413
PA514
PA615
PA716
PA817
PA918
PB219
PB85
PB96
PA1036
PA1137
PA1238
PA13-JTMS_SWDIO39
PA14-JTCK_SWCLK41
PA15-JTDI42
PB3-JTDO43
PB4-NJTRST44
PB545
PB646
PB747
PB028
PB129
PE430
U1E
STM32WBx5_QFN48BOOT0
GND
C7100nF
GND
C6100nF
GND
C5100nF
VDD
L3
10nH
GND GND
C140.8pF
L4 2.7nH
GND GND
C140.8pF
L4 2.7nHnn
50 Ohms Matching Network
C150.3pF
50 ohms RF output8 4
1
FLT1LFL212G45TC1A007
GND
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Schematics
AN
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10/18A
N5290 R
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Figure 7. Optimized solution with discrete components
(STM32WBx0xx products)
RF022
RF121
VDDRF23
U1A
STM32WBx0_QFN48
OSC_IN25
OSC_OUT24
PC14-OSC32_IN2
PC15-OSC32_OUT3
PH3-BOOT04
AT026
AT127
NRST7
U1C
STM32WBx0_QFN48
VDD
GNDGND
GND
NRST
GND
C415pF
GND
C315pF
X2NX2012_32K768
X1
NX2016_32M
GND
VDD
GND
GND
C8100nF
C12100nF
L1
IND_FCM1608KF-601T03
GNDGND
VDD
C1100nF
C2
100pF
C11100nF
GND
PA0-CK_IN9
PA110
PA211
PA312
PA413
PA514
PA615
PA716
PA817
PA918
PB219
PB85
PB96
PA1036
PA1137
PA1238
PA13-JTMS_SWDIO39
PA14-JTCK_SWCLK41
PA15-JTDI42
PB3-JTDO43
PB4-NJTRST44
PB545
PB646
PB747
PB028
PB129
PE430
U1E
STM32WBx0_QFN48BOOT0
GND
C7100nF
GND
C6100nF
GND
C5100nF
VDD
GND GND
C140.8pF
L4 2.7nH
GND GND
C140.8pF
L4 2.7nHnn
50 Ohms Matching Network
C150.3pF
50 ohms RF output8 4
1
FLT1LFL212G45TC1A007
GND
VDD34
VSS32
VDD33
VDD31
VDD
VSS
VDD
VDD
U1B
STM32WBx0_QFN48
VDDA/VREF+8
VDD/VDDT20
VDD35
VDD40
VBAT1
VDD48
VS
S(E
xPA
D)
49
U1D
STM32WBx0_QFN48
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Figure 8. Optimized solution with IPD (STM32WBx5xx products)
RF022
RF121
VDDRF23
U1A
STM32WBx5_QFN48
OSC_IN25
OSC_OUT24
PC14-OSC32_IN2
PC15-OSC32_OUT3
PH3-BOOT04
AT026
AT127
NRST7
U1C
STM32WBx5_QFN48
VDDA/VREF+8
VDD/VDDT20
VDD35
VDDUSB40
VBAT1
VDD48
VS
S(E
xPA
D)
49
U1D
STM32WBx5_QFN48
VDD
GND
GND
GNDGND
GND
NRST
C104.7uF
C13
4.7uF
GND
C415pF
GND
C315pF
X2NX2012_32K768
X1
NX2016_32M
GND
VDDUSB
VDD
GND
GND
GND
C8100nF
C9100nF
C12100nF
L1
IND_FCM1608KF-601T03
GNDGND
VDD
C1100nF
C2
100pF
L210uH
C11100nF
GND
VDDSMPS34
VSSSMPS32
VLXSMPS33
VFBSMPS31
VDDSMPS
VSSSMPS
VLXSMPS
VFBSMPS
U1B
STM32WBx5_QFN48
PA0-CK_IN9
PA110
PA211
PA312
PA413
PA514
PA615
PA716
PA817
PA918
PB219
PB85
PB96
PA1036
PA1137
PA1238
PA13-JTMS_SWDIO39
PA14-JTCK_SWCLK41
PA15-JTDI42
PB3-JTDO43
PB4-NJTRST44
PB545
PB646
PB747
PB028
PB129
PE430
U1E
STM32WBx5_QFN48
GND
IN5
OUT6
GN
D2
2
GN
D1
1
GN
D3
3
GN
D4
4
IPD1
BOOT0
GND
C7100nF
GND
C6100nF
GND
C5100nF
VDD
L3
10nH
50 ohms RF output
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Schematics
AN
5290
12/18A
N5290 R
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Figure 9. Optimized solution with IPD (STM32WBx0xx products)
RF022
RF121
VDDRF23
U1A
STM32WBx0_QFN48
OSC_IN25
OSC_OUT24
PC14-OSC32_IN2
PC15-OSC32_OUT3
PH3-BOOT04
AT026
AT127
NRST7
U1C
STM32WBx0_QFN48
VDD
GNDGND
GND
NRST
GND
C415pF
GND
C315pF
X2NX2012_32K768
X1
NX2016_32M
GND
VDD
GND
GND
C8100nF
C12100nF
L1
IND_FCM1608KF-601T03
GNDGND
VDD
C1100nF
C2
100pF
C11100nF
GND
PA0-CK_IN9
PA110
PA211
PA312
PA413
PA514
PA615
PA716
PA817
PA918
PB219
PB85
PB96
PA1036
PA1137
PA1238
PA13-JTMS_SWDIO39
PA14-JTCK_SWCLK41
PA15-JTDI42
PB3-JTDO43
PB4-NJTRST44
PB545
PB646
PB747
PB028
PB129
PE430
U1E
STM32WBx0_QFN48
GND
IN5
OUT6
GN
D2
2
GN
D1
1
GN
D3
3
GN
D4
4
IPD1
BOOT0
GND
C7100nF
GND
C6100nF
GND
C5100nF
VDD
50 ohms RF output
VDDA/VREF+8
VDD/VDDT20
VDD35
VDD40
VBAT1
VDD48
VS
S(E
xPA
D)
49
U?D
STM32WBx0_QFN48
VDD34
VSS32
VDD33
VDD31
VDD
VSS
VDD
VDD
U?B
STM32WBx0_QFN48
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Figure 10. Solution without SMPS (STM32WBx5xx products)
1. For STM32WB55Vx add L and R, as indicated in Section 1.2: LDO
configuration for VDD > 3 V
RF022
RF121
VDDRF23
U1A
STM32WBx5_QFN48
OSC_IN25
OSC_OUT24
PC14-OSC32_IN2
PC15-OSC32_OUT3
PH3-BOOT04
AT026
AT127
NRST7
U1C
STM32WBx5_QFN48
VDDA/VREF+8
VDD/VDDT20
VDD35
VDDUSB40
VBAT1
VDD48
VS
S (
Ex
PAD
)4
9
U1D
STM32WBx5_QFN48
VDD
GNDGND
GND
NRST
GND
C415pF
GND
C315pF
X2NX2012_32K768
X1
NX2016_32M
GND
VDDUSB
VDD
GND
GND
GND
C8100nF
C9100nF
C12100nF
L1
IND_FCM1608KF-601T03
GNDGND
VDD
C1100nF
C2
100pF
C11100nF
GND
VDDSMPS34
VSSSMPS32
VLXSMPS33
VFBSMPS31
VDDSMPS
VSSSMPS
VLXSMPS
VFBSMPS
U1B
STM32WBx5_QFN48
PA0-CK_IN9
PA110
PA211
PA312
PA413
PA514
PA615
PA716
PA817
PA918
PB219
PB85
PB96
PA1036
PA1137
PA1238
PA13-JTMS_SWDIO39
PA14-JTCK_SWCLK41
PA15-JTDI42
PB3-JTDO43
PB4-NJTRST44
PB545
PB646
PB747
PB028
PB129
PE430
U1E
STM32WBx5_QFN48
GND
IN5
OUT6
GN
D2
2
GN
D1
1
GN
D3
3
GN
D4
4
IPD1
BOOT0
GND
C7100nF
GND
C6100nF
GND
C5100nF
VDD
50 ohms RF output
1
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Bill of materials AN5290
14/18 AN5290 Rev 6
3 Bill of materials
Table 1. Bill of materials - Optimized solution with discrete
componentsDesignator Description Comment Footprint Manufacturer
Part number
C1, C5, C6, C7, C8, C9, C11, C12
Capacitor, not polarized (X5R)
100 nFdecoupling capacitors
0402
Murata GRM155R61H104KE19D
C2
Capacitor, not polarized
100 pFdecoupling capacitors Yageo CC0402KRX7R9BB101
C3, C4 15 pFLSE crystal capacitor
Murata
GRM1555C1H4R3CA01D
C10, C13 4.7 µFdecoupling capacitor GRM155R61A475MEAAD
C14 0.8 pFmatching network GRM1555C1HR80BA01D
C15 0.3 pFmatching network GRM1555C1HR30WA01D
L1 Coil Filtering coil 0603 TAI-TECH FCM1608KF-601T03
L2
Inductor
10 µHSMPS inductor 0805
Murata
LQM21FN100M70L
L3 10 nHSMPS inductor0402
LQG15WZ10NJ02D
L4 2.7 nHmatching network LQG15HS2N7S02D
X1Crystal
32 MHz - HSE NX2016NDK
NX2016SA_32MHz
X2 32.768 kHz - LSE NX2012 NX2012SA_32-768kHz
FLT1 Low-pass filter Harmonics rejection - Murata
LFL212G45TC1A007
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AN5290 Rev 6 15/18
AN5290 Bill of materials
17
Table 2. Bill of materials- Optimized solution with
IPDDesignator Description Comment Footprint Manufacturer Part
number
C1, C5, C6, C7, C8, C9, C11, C12
Capacitor, not polarized (X5R)
100 nFdecoupling capacitors
0402
Murata GRM155R61H104KE19D
C2
Capacitor, not polarized
100 pFdecoupling capacitors Yageo CC0402KRX7R9BB101
C3, C4 15 pFLSE crystal capacitorMurata
GRM1555C1H4R3CA01D
C10, C13 4.7 µFdecoupling capacitor GRM155R61A475MEAAD
L1 Coil Filtering coil 0603 TAI-TECH FCM1608KF-601T03
L2Inductor
10 µHSMPS inductor 0805
MurataLQM21FN100M70L
L3 10 nHSMPS inductor 0402 LQG15WZ10NJ02D
X1Crystal
32 MHz - HSE NX2016NDK
NX2016SA_32MHz
X2 32.768 kHz - LSE NX2012 NX2012SA_32-768kHz
IPD1 Integrated passive deviceMatching network and low-pass
filter
Bumpless CSP STMicroelectronics MLPF-WB55-01E3
Table 3. Bill of materials - Solution without SMPSDesignator
Description Comment Footprint Manufacturer Part number
C1, C5, C6, C7, C8, C9, C11, C12
Capacitor, not polarized (X5R)
100 nFdecoupling capacitors
0402
Murata GRM155R61H104KE19D
C2Capacitor, not
polarized
100 pFdecoupling capacitors Yageo CC0402KRX7R9BB101
C3, C4 15 pFLSE crystal capacitor Murata GRM1555C1H4R3CA01D
L1 Coil Filtering coil 0603 TAI-TECH FCM1608KF-601T03
X1Crystal
32 MHz - HSE NX2016NDK
NX2016SA_32MHz
X2 32.768 kHz - LSE NX2012 NX2012SA_32-768kHz
IPD1 Integrated passive deviceMatching network and low-pass
filter
Bumpless CSP STMicroelectronics MLPF-WB55-01E3
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Conclusion AN5290
16/18 AN5290 Rev 6
4 Conclusion
The devices of the STM32WB Series show excellent RF performance
(detailed in the product datasheets available on www.st.com), with
a minimal set of external components associated with a PCB layout
that complies with RF guidelines.
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AN5290 Rev 6 17/18
AN5290 Revision history
17
5 Revision history
Table 4. Document revision historyDate Revision Changes
14-Feb-2019 1 Initial release.
20-Feb-2019 2Updated Section 1.1: SMPS and LDO
configurations.Updated Table 2: Bill of materials- Optimized
solution with IPD.
25-Sep-2019 3
Updated Section 1.1: SMPS and LDO configurations and Section 4:
Conclusion.Updated Figure 4: HSE trimming, Figure 6: Optimized
solution with discrete components (STM32WBx5xx products), Figure 8:
Optimized solution with IPD (STM32WBx5xx products) and Figure 10:
Solution without SMPS (STM32WBx5xx products).Added Figure 7:
Optimized solution with discrete components (STM32WBx0xx products)
and Figure 9: Optimized solution with IPD (STM32WBx0xx
products).
22-Jan-2020 4
Updated Table 1: Bill of materials - Optimized solution with
discrete components, Table 2: Bill of materials- Optimized solution
with IPD and Table 3: Bill of materials - Solution without
SMPS.Updated Figure 6: Optimized solution with discrete components
(STM32WBx5xx products), Figure 7: Optimized solution with discrete
components (STM32WBx0xx products), Figure 8: Optimized solution
with IPD (STM32WBx5xx products), Figure 9: Optimized solution with
IPD (STM32WBx0xx products) and Figure 10: Solution without SMPS
(STM32WBx5xx products).
12-May-2020 5Updated Figure 1: Supply configurations.Added
Section 1.2: LDO configuration for VDD > 3 V.
22-Jul-2020 6
Updated Section 1.2: LDO configuration for VDD > 3 V.Updated
Figure 3: Recommended schematic for the no SMPS configurations
(STM32WB55Vx).Added footnote to Figure 10: Solution without SMPS
(STM32WBx5xx products).
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AN5290
18/18 AN5290 Rev 6
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1 Design considerations1.1 SMPS and LDO configurationsFigure 1.
Supply configurations
1.2 LDO configuration for VDD > 3 VFigure 2. LDO
configurationFigure 3. Recommended schematic for the no SMPS
configurations (STM32WB55Vx)
1.3 HSE trimmingFigure 4. HSE trimming
1.4 RF matchingFigure 5. RF matching and external filters
2 SchematicsFigure 6. Optimized solution with discrete
components (STM32WBx5xx products)Figure 7. Optimized solution with
discrete components (STM32WBx0xx products)Figure 8. Optimized
solution with IPD (STM32WBx5xx products)Figure 9. Optimized
solution with IPD (STM32WBx0xx products)Figure 10. Solution without
SMPS (STM32WBx5xx products)
3 Bill of materialsTable 1. Bill of materials - Optimized
solution with discrete componentsTable 2. Bill of materials-
Optimized solution with IPDTable 3. Bill of materials - Solution
without SMPS
4 Conclusion5 Revision historyTable 4. Document revision
history