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

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

AN5290 Rev 6 3/18

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

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

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

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

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

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

AN

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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

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

AN

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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

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

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

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

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.

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).

AN5290

18/18 AN5290 Rev 6

IMPORTANT NOTICE – PLEASE READ CAREFULLY

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© 2020 STMicroelectronics – All rights reserved

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