Texas Instruments | CC13xx/CC26xx Hardware Configuration and PCB Design Considerations (Rev. C) | Application notes | Texas Instruments CC13xx/CC26xx Hardware Configuration and PCB Design Considerations (Rev. C) Application notes

Texas Instruments CC13xx/CC26xx Hardware Configuration and PCB Design Considerations (Rev. C) Application notes
Application Report
SWRA640C – December 2018 – Revised September 2019
CC13xx/CC26xx Hardware Configuration and PCB Design
Considerations
ABSTRACT
This application report provides design guidelines for the CC13xx/CC26xx SimpleLink™ ultra-low-power
wireless MCU platform. There is an overview of the different reference designs followed by RF front-end,
schematic, PCB, and antenna design considerations. The report also covers crystal oscillator tuning,
optimum load impedance as well as a brief explanation of the different power supply configurations. At the
end there is a summary of steps to carry out at board bring-up.
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Contents
Reference Design ............................................................................................................ 2
Front-End Configurations ................................................................................................... 7
Schematic ................................................................................................................... 10
PCB Layout ................................................................................................................. 14
Antenna ...................................................................................................................... 20
Crystal Tuning .............................................................................................................. 25
Integrated Passive Component (IPC).................................................................................... 29
Optimum Load Impedance ................................................................................................ 30
Power Supply Configuration .............................................................................................. 31
Board Bring-Up ............................................................................................................. 34
References .................................................................................................................. 37
List of Figures
1
CC13xx/CC26xx Front-End Options (red = required if external bias is used) ....................................... 7
2
Comparison of CC13xx/CC26xx Front-End Options .................................................................... 8
3
CC13xx TX Only Matching (868/915 MHz)............................................................................... 9
4
CC13xx RX Only Matching (868/915 MHz) .............................................................................. 9
5
CC1312R 7x7 RF Part Schematic Overview ........................................................................... 10
6
CC1312R 7x7 Decoupling Capacitors ................................................................................... 11
7
CC1312R Board Stack Up ................................................................................................ 14
8
CC1312R Balun and LC Filter PCB Layout
9
LC Filter PCB Layout Design Guideline ................................................................................. 16
10
Decoupling Capacitors and VIA to Ground ............................................................................. 17
11
Current Return Path
18
12
CC1312R DC/DC Regulator PCB Layout
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..............................................................................
Recommended Antenna PI-Match Network for Single-Band Antennas.............................................
Recommended Antenna Match Network for Dual-Band Antennas ..................................................
Matching the Low-Band With CLOW: 5.6 pF and LLOW: NC .............................................................
Matching the High-Band With an Ideal Value of LHIGH: 2.2 nH and CHIGH: NC ......................................
Smith Chart With Final Match Values of LHIGH: 3.3 nH and CLOW: 5.6 pF ............................................
VSWR Chart With Final Match Values of LHIGH: 3.3 nH and CLOW: 5.6 pF ...........................................
Recommended Antenna Match Network for Dual-Band Antennas (433-510 MHz & 2.4 GHz) ..................
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1
Reference Design
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20
VSWR Chart With Final Match Values of LANT: 33 nH LHIGH: 3.9 nH and CLOW: 0 Ω ................................ 24
21
CC1312R With 32 kHz and 48 MHz Crystals
22
Pierce Type Oscillator ..................................................................................................... 26
23
DC/DC Mode................................................................................................................ 31
24
Global LDO Mode .......................................................................................................... 32
25
External Regulator Mode .................................................................................................. 33
..........................................................................
25
List of Tables
1
CC13xx/CC26xx Reference Design Overview ........................................................................... 6
2
CC26x0/CC13x0 and CC26x2/CC13x2 Pins With up to 8 mA Drive Strength ..................................... 11
3
CC13x0/CC26x0 and CC13x2/CC26x2 Configuration of Signal Interfaces ........................................ 12
4
CC13x2/CC26x2 Pin Mapping............................................................................................ 12
5
CC13x0/CC26x0 Pin Mapping............................................................................................ 13
6
CC26x0/CC13x0 and CC26x2/CC13x2 JTAG Pins
7
Cap-Array Delta ............................................................................................................ 27
8
Available IPC’s.............................................................................................................. 29
...................................................................
13
Trademarks
SimpleLink, LaunchPad, SmartRF are trademarks of Texas Instruments.
Bluetooth is a registered trademark of Bluetooth SIG, Inc and used by Motorola, Inc. under license.
All other trademarks are the property of their respective owners.
1
Reference Design
A TI LaunchPad™ is the main development platform for CC13xx and CC26xx devices. A LaunchPad
includes optimized external RF components on-board, PCB antenna and built-in debugger providing an
easy-to-use development environment with a single core software development kit (SDK) and rich tool set.
Each CC13xx/CC26xx family member is featured on a dedicated LaunchPad with RF matching network
and an antenna optimized for operation at one or more of the supported ISM bands. All TI LaunchPad
design files, including Gerber-files and CAD source, are available for download at ti.com and can be used
as a reference design when integrating CC13xx/CC26xx into custom hardware.
1.1
Sub-1 GHz LaunchPads
This section provides the different LaunchPad designs and which design to follow for a specific
CC13xx/CC26xx device and ISM band.
1.1.1
LAUNCHXL-CC1310
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
2
CC1310
868 MHz and 915 MHz
Monopole PCB Antenna with Single or Dual Band Option
Differential, external bias
LAUNCHXL-CC1310 Design Files
CC13xx/CC26xx Hardware Configuration and PCB Design Considerations SWRA640C – December 2018 – Revised September 2019
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1.1.2
LAUNCHXL-CC1312R
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
1.2
1.2.1
CC1312R
868 MHz and 915 MHz
Monopole PCB Antenna with Single or Dual Band Option
Differential, external bias
SimpleLink Sub-1 GHz CC1312R Wireless (MCU) LaunchPad Dev Kit
868MHz/915MHz App
2.4 GHz LaunchPads
LAUNCHXL-CC2640R2
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
1.2.2
CC2640R2F
2.4 GHz
2.4-GHz Inverted F Antenna
Differential, internal bias
LAUNCHXL-CC2640R2 Design Files
LAUNCHXL-CC26x2R
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
CC2652R
2.4 GHz
2.4-GHz Inverted F Antenna
Differential, internal bias
CC26x2R LaunchPad Design Files
This LaunchPad can also be used for development with CC2642R.
1.3
1.3.1
Dual-Band LaunchPads
LAUNCHXL-CC1350EU/US
This LaunchPad uses an RF switch to select either the 868 MHz/915 MHz RF front end and antenna or
the 2.4 GHz front end and antenna. Note that the LaunchPad comes in two different versions: EU and US.
The only difference between the two is the antenna matching components that are optimized for either
868 MHz (EU) or 915 MHz (US) operation.
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
CC1350
868 MHz/915 MHz and 2.4 GHz
• Miniature Helical PCB Antenna for 868 MHz or 915/920 MHz
• 2.4-GHz Inverted F Antenna
Differential, external bias
LAUNCHXL-CC1350 Design Files
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Reference Design
1.3.2
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LAUNCHXL-CC1350-4
This LaunchPad uses an RF switch to select either the 433 MHz RF front end and antenna or the 2.4 GHz
front end and antenna.
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
1.3.3
CC1350
433 MHz and 2.4 GHz
• Miniature Helical PCB Antenna for 868 MHz or 915/920 MHz
• 2.4-GHz Inverted F Antenna
Differential, external bias
CC1350 Dual Band Launchpad for 433 MHz/ 2.4 GHz Band Rev A
LAUNCHXL-CC1352R
Revision A of this LaunchPad uses an RF switch to route either the 868 MHz/915 MHz or 2.4 GHz RF
front end into the shared tri-band antenna. For more information about the antenna, see Section 5.2.1.
Revision B of this LaunchPad uses a diplexer instead of a switch to combine the two RF paths into the
shared antenna, which frees up one DIO as a control signal for the switch is no longer needed.
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
1.3.4
CC1352R
868 MHz, 915 MHz and 2.4 GHz
Based on Monopole PCB Antenna with Single or Dual Band Option
Differential, external bias
CC1352R LaunchPad Design Files
LAUNCHXL-CC1352P1
This LaunchPad has an 868 MHz/915 MHz RF front end at the high power PA port, which enables up to
+20 dBm output power in the respective ISM bands. The regular sub-1 GHz port also has an 868
MHz/915 MHz RF front end to be able to receive and transmit at up to +14 dBm output power in the 868
MHz/915 MHz bands. Also, a 2.4 GHz RF front end is available at the 2.4 GHz port to be able to receive
and transmit at up to +5 dBm output power in the 2.4 GHz band. All three paths share the same antenna
and an RF switch selects which RF path to connect to the antenna. The switch has an insertion loss of
approximately 0.5 dB. This is accounted for in the CC1352P SimpleLink™ High-Performance Dual-Band
Wireless MCU With Integrated Power Amplifier Data Sheet RF performance figures. For more information
about the antenna, see Section 5.2.1.
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
4
CC1352R
868 MHz, 915 MHz and 2.4 GHz
Based on Monopole PCB Antenna with Single or Dual Band Option
Differential, external bias
CC1352R LaunchPad Design Files
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Reference Design
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1.3.5
LAUNCHXL-CC1352P-2
This LaunchPad has a 2.4 GHz RF front end at the high power PA port, which enables up to +20 dBm
output power in the respective ISM band. The regular 2.4 GHz port has a 2.4 GHz RF front end to be able
to receive and transmit at up to +5 dBm output power in the 2.4 GHz band. Also, an 868 MHz/915 MHz
RF front end is available at the sub-1 GHz port to be able to receive and transmit up to +14 dBm output
power in the 868 MHz/915 MHz bands. All three paths share the same antenna and an RF switch selects
which RF path to connect to the antenna. The switch has an insertion loss of approximately 0.5 dB. This is
accounted for in the CC1352P SimpleLink™ High-Performance Dual-Band Wireless MCU With Integrated
Power Amplifier Data Sheet RF performance figures. For more information about the antenna, see
Section 5.2.1.
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
1.3.6
CC1352P
868 MHz, 915 MHz and 2.4 GHz
Based on Monopole PCB Antenna with Single or Dual Band Option
Differential, external bias
LAUNCHXL-CC1352P-2 Design Files
LAUNCHXL-CC1352P-4
This LaunchPad has a 470 MHz/510 MHz RF front end on the high power PA port, which enables up to
+20 dBm output power in the respective ISM bands. The regular sub-1 GHz port has an RF front end to
be able to receive and transmit at up to +14 dBm output power in the 433 MHz, 470 MHz and 510 MHz
ISM bands. Also, a 2.4 GHz RF front end is available to be able to receive and transmit at up to +5 dBm
output power in the 2.4 GHz band. All three paths share the same antenna and an RF switch selects
which RF path to connect to the antenna. The switch has an insertion loss of approximately 0.5 dB. This is
accounted for in the CC1352P SimpleLink™ High-Performance Dual-Band Wireless MCU With Integrated
Power Amplifier Data Sheet RF performance figures. The antenna is dual-band and supports operation at
one sub-1 GHz frequency in addition to 2.4 GHz. The antenna must be tuned to work with either 433 MHz
and 2.4 GHz, 470 MHz and 2.4 GHz, or 510 MHz and 2.4 GHz. For more information, see the devicespecific design files. For more information about the antenna, see Section 5.2.2.
Featured device:
ISM band:
Antenna:
RF front end:
Design files:
CC1352P
433 MHz, 470 MHz, 510 MHz and 2.4 GHz
Based on Monopole PCB Antenna with Single or Dual Band Option
Differential, external bias
LAUNCHXL-CC1352P-4 Design Files
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Reference Design
1.4
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Reference Design Overview
When designing a custom board, the reference design should be followed as much as possible. Not all
combinations of CC13xx/CC26xx devices and ISM bands are covered by a reference design, but it is
possible to use an RF front end from one reference design and combine it with a compatible
CC13xx/CC26xx device. Table 1 shows which CC13xx/CC26xx reference design to use for a given ISM
band.
As an example, if the application requires operation in the 433 MHz band, but does not need 2.4 GHz
operation or +20 dBm transmit power, the CC1312R device can be used instead of CC1352P. Then, the
LAUNCHXL-CC1352P-4 reference design should be followed, but only the RF front end on the SUB1_GHZ_RF_P/N pins is required.
Table 1. CC13xx/CC26xx Reference Design Overview
Supported
Device
Reference Design
433 MHz
470 MHz
510 MHz
CC1310
CC13xxEM-7XD-4251
779 MHz
868 MHz
915 MHz
CC1310
LAUNCHXL-CC1310
CC1312R
LAUNCHXL-CC1312R1
CC26x0
CC2650EM-7ID
Characterization board for CC26x0. Using the
7x7 QFN in combination with differential RF,
internal bias.
CC2650EM-5XD
Characterization board for CC26x0. Using the
5x5 QFN in combination with differential RF,
external bias.
CC2650EM-4XS
Characterization board for CC26x0. Using the
4x4 QFN in combination with single ended RF,
internal bias.
CC2650EM-4XS_Ext_Reg
Characterization board for CC26x0. Using the
4x4 QFN in External Regulator mode
configuration.
Frequency Band
CC1312R
2.4 GHz
LAUNCHXL-CC1352P-4
Use the 433 MHz front end from the CC1352P
reference design
For other reference designs, see the following
link
LAUNCHXL-CC2640R2
Evaluation and development platform.
CC2640R2
CC2640EM-CXS
Characterization board for the CC2640R2F
WCSP.
CC2642R
CC2652R
LAUNCHXL-CC26x2R1
Evaluation and development platform.
CC26x2REM-7ID
Characterization board.
CC1350
LAUNCHXL-CC1350-4
CC1352P
LAUNCHXL-CC1352P-4
CC1350
LAUNCHXL-CC1350
CC1352R
LAUNCHXL-CC1352R1
• 433 MHz
• 2.4 GHz
• 868 / 915 MHz
• 2.4 GHz
CC1352REM-XD7793-XD24
Multi band
CC1352P
LAUNCHXL-CC1352P1
CC1352PEM-XD7793-XD24-PA9093
LAUNCHXL-CC1352P-2
CC1352PEM-XD7793-XD24-PA24
6
Comment
• 868 / 915 MHz @ 20 dBm
• 2.4 GHz @ 5 dBm
• 868 / 915 MHz @ 14 dBm
• 2.4 GHz @ 20 dBm
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Front-End Configurations
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2
Front-End Configurations
2.1
CC13xx/CC26xx
CC13xx and CC26xx have the following front-end modes:
• Single ended: Either the RF_P pin or the RF_N pin is used as the RF path.
• Differential: Both RF_P and RF_N are used as a differential RF interface.
• Internal or external bias of the LNA: The LNA can be biased by an internal or external inductor. Both
types of biasing can be selected for single-ended and differential configuration.
Figure 1 shows the front-end options. Components and connecitons in red color are not required if internal
bias is used. The component values depend on the frequency band of operation.
Pin 3 (RX_TX)
Antenna
(50 ohm)
Pin 2 (RF_N)
Pin 1 (RF_P)
Differential operation
Antenna
(50 ohm)
Pin 3 (RX_TX)
or pin 2 (RF_N)
Pin 1 (RF_P)
Single-ended operation
Antenna
(50 ohm)
Pin 3 (RX_TX)
Pin 2 (RF_N)
Antenna
(50 ohm)
Pin 1 (RF_P)
Single-ended operation with antenna diversity or dual band
Figure 1. CC13xx/CC26xx Front-End Options (red = required if external bias is used)
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Front-End Configurations
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Figure 2 summarizes the pros and cons of the different solutions. All numbers in the figure are compared
to a differential front end and external biasing.
Single-Ended
Differential
External Bias
Internal Bias
Pros
x Best RX performance
x Best TX performance
Pros
x Slightly smaller footprint
x Slightly lower BOM cost
Cons
x Biggest footprint
x Highest BOM cost
Cons
x 1 dB lower sensitivity
Pros
x Small footprint
x Lower BOM cost
Pros
x Smallest footprint
x Lowest BOM cost
Cons
x 1 dB lower sensitivity
x 3 dB lower output power
Cons
x 2 dB lower sensitivity
x 3 dB lower output power
Figure 2. Comparison of CC13xx/CC26xx Front-End Options
2.2
Configuring Front-End Mode
The front-end mode is set in the CMD_RADIO_SETUP command:
• Config.frontEndMode = 0x00: Differential mode
• Config.frontEndMode = 0x01: Single-ended mode RFP
• Config.frontEndMode = 0x02: Single-ended mode RFN
For single-ended operation that uses one RF pin in RX and the other RF pin in TX, an additional override
has to be set:
ADI_HALFREG_OVERRIDES(0, 16, 0x7, x)
(1)
where, x = 1 configures the PA output on RFP and x = 0 configures the PA output on RFN.
For single-ended operation, the pin set by CMD_RADIO_SETUP Config.frontEndMode will be used in RX
and the pin set by the ADI_HALFREG_OVERRIDE override will be used in TX.
The LNA biasing is set in the CMD_RADIO_SETUP command:
• config.biasMode = 0: Internal bias
• config.biasMode = 1: External bias
8
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Front-End Configurations
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2.3
2.3.1
CC13xx Single-Ended Mode
Single-Ended RX/TX
A typical sub-1 GHz design usually requires long range and a differential design is typically used. For
lower cost and a smaller footprint, a single-ended design can be used at the expense of shorter range.
The sub-1 GHz part from CC1350STK Design Files can be used for a single ended-design.
If CC13xx is interfaced to a front-end module (FEM) with dedicated 50 Ω ports for RX and TX, fewer
components than in the single-ended RX/TX design are needed. This is covered in Section 2.3.2 and
Section 2.3.3 for TX and RX only.
2.3.2
Single-Ended TX Only
Load pull measurements show that maximum output power can be achieved if the single-ended RF pin
sees 14 – j20Ω. A suggested matching network is shown Figure 3. This match gives an output power of
11.8 dBm, 2nd harmonic of -39 dBm, and 3rd harmonic of -42 dBm (measured on 3 units @25°, 3.0 V,
868 MHz). Note that single-ended measurements have not been done for 433 MHz.
C3
0.5pF
1
RF PIN
L1
5.6nH
4
3
5
2
C4
120pF
1
2
C1
5.6pF
C2
1.8pF
Figure 3. CC13xx TX Only Matching (868/915 MHz)
2.3.3
Single-Ended RX Only
Source pull measurements show that best sensitivity can be achieved if the single-ended RF pin sees 47
+ j26Ω. A suggested matching network is shown Figure 4. Using this match gives sensitivity of -110 dBm
(measured on 3 units @25°, 3.0 V, 868 MHz). Note that single-ended measurements have not been done
for 433 MHz.
4
3
5
C2
120pF
RF PIN
1
C4
2
1
2
1
L1
68nH
RX_TX
L2
8.2nH
120pF
C3
1.2pF
2
C1
68pF
Figure 4. CC13xx RX Only Matching (868/915 MHz)
2.4
CC26xx
For CC26xx, a single-ended configuration is recommended when maximum output power is not needed.
For 0 dBm output power using single-ended mode, the current consumption and component count will be
lower than for the corresponding differential mode.
Reference designs for both single-ended and differential configurations are available.
1. Go to: http://www.ti.com/product/CC2640R2F/technicaldocuments.
2. Scroll down to “Design Files”.
3. The designs are named 4XS, 5XD and 7ID. The first number indicate the packet size, X - External
bias, I - Internal bias, S – Single-ended, D – Differential.
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Schematic
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3
Schematic
3.1
Schematic Overview
Figure 5 shows the different components discussed in the following sub-sections.
VDDS
R351
100k
VDDS
nRESET
U1A
C351
0.1uF
JTAG_TMS
JTAG_TCK
24
25
35
DCDC_SW
33
4
5
Y1
C41
12pF
VDDR
32.768kHz
C51
12pF
23
49
C231
1uF
JTAG_TMSC
JTAG_TCKC
RESET_N
VDDS2
VDDS3
VDDS
VDDS_DCDC
VDDR
VDDR_RF
DCDC_SW
X32K_Q1
X32K_Q2
DCOUPL
EGP
RF_P
RF_N
RX_TX
X48M_N
X48M_P
13
22
44
34
45
48
C11
3.6pF
1
1
1
2
3
L11
27nH
2
L12
7.5nH
C12
2.7pF
1
L14
2
1
6.8nH
C22
2
46
47
L13
1
C15
2
6.8nH
C13
6.2pF
C14
3pF
100pF
3.6pF
L21
7.5nH
CC1312R1F3RGZ
2
C21
100pF
Y2
48MHz
1
C473
7.5pF
3
2
4
C461
7.5pF
Using external crystal load capacitors instead of internal:
C461 and C473: 7.5 pF
Figure 5. CC1312R 7x7 RF Part Schematic Overview
3.1.1
24/48 MHz Crystal
A 24/48 MHz crystal is required as the frequency reference for the radio.
For CC26x2/CC13x2, there will be spurs at N x 48 MHz offset from the carrier. These spurs are caused by
the current going back and forth between the crystal and the XOSC tuning capacitors (which form the
oscillator tank together with off-chip capacitances). This current is quite large due to the high Q of the
crystal tank and will create an IR drop on the power rails that are shared with the PA and VCO. Setting the
XOSC tuning capacitors to zero reduces the spurs by approximately 5 dB for the largest spur compared to
the default setting.
The internal capacitor array can be used in most use cases, but it is recommended to use external crystal
loading capacitors and setting the internal XOSC tuning capacitors to zero for systems targeting
compliance with ARIB STD T-108 and Chinese regulations in 470 – 510 MHz frequency band as well as
when using the +20 dBm PA. For information on how to set the internal XOSC tuning capacitors, see
Section 6.4.
3.1.2
32.768 kHz Crystal
The 32.768-kHz crystal is optional. The internal low-speed RC oscillator (32-kHz) can be used as a
reference if the low-power crystal oscillator is not used. The RC oscillator can be calibrated automatically
to provide a sleep timer accurate enough for Bluetooth® Low Energy. Using an external crystal has the
advantage that it increases sleep clock accuracy and reduces the power consumption for Bluetooth Low
Energy (shorter RX windows around connection events). An external crystal is required for time
synchronous protocols such as TI 15.4-Stack and wM-Bus.
10
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Schematic
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3.1.3
Balun
A balun is a network that transforms from a balanced (differential) to an unbalanced (single-ended) signal,
hence the name balun. The balun has a ±90° phase shift implemented by using a low-pass filter and a
high-pass filter. The important part is to keep the balun as symmetrical as possible. If only one of the RF
pins is used for RF output/input no balun is required. In this case, a filter is required between the chip and
the antenna. For details, see Section 2.3.
3.1.4
Filter
An LC filter is placed between the balun and the antenna. The filter has two functions: attenuate
harmonics and perform impedance transformation to 50 Ω. The latter is important since measuring
equipment such as spectrum analyzers and RF signal generators provide a 50 Ω load. The word filter
balun is sometimes used to describe all the components necessary to implement a balun, filter and to
ensure proper impedance matching between the radio and the antenna.
3.1.5
RX_TX Pin
This pin is not present on all CC26x0/CC13x0 and CC26x2/CC13x2 devices. This pin provides ground
connection for the input LNA in RX. This is referred to as external bias and improves sensitivity by
approximately 1 dB compared to using internal biasing of the LNA.
3.1.6
Decoupling Capacitors
In the reference design, there are several decoupling capacitors. The schematic tells which supply pin the
decoupling capacitor is supposed to decouple.
VDD_EB
VDDS Decoupling Capacitors
VDDS
VDDR
FL1
VDDR Decoupling Capacitors
L331
Pin 13
Pin 22
Pin 44
Pin 34
Pin 45
DCDC_SW
BLM18HE152SN1
Pin 48
6.8uH
C1
22uF
C131
0.1uF
C221
0.1uF
C441
0.1uF
C341
22uF
C342
0.1uF
C331
22uF
C451
0.1uF
C481
0.1uF
Place L331 and C331 close to pin 33.
Low inductance ground for C331
Figure 6. CC1312R 7x7 Decoupling Capacitors
3.1.7
Antenna Components
A pi-match network is recommended between the LC filter and the antenna for antenna impedance
matching. For more information, see Section 5.1.
3.1.8
RF Shield
An RF shield is used on some of the TI reference designs to reduce the radiation of spurious signals. Most
notably is the 3rd harmonic emission.
3.1.9
I/O Pins Drive Strength
The I/O pins have configurable drive strength and maximum current. All I/O pins support 2 mA and 4 mA,
while five pins support up to 8 mA.
Table 2. CC26x0/CC13x0 and CC26x2/CC13x2 Pins With up to 8 mA Drive Strength
7 × 7 QFN (RGZ)
5 × 5 QFN (RHB)
WCSP (YFV)
4 × 4 QFN (RSM)
DIO5
DIO2
DIO2
DIO0
DIO6
DIO3
DIO3
DIO1
DIO7
DIO4
DIO4
DIO2
DIO16
DIO5
DIO5
DIO3
DIO17
DIO6
DIO6
DIO4
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Bootloader Pins
The bootloader communicates with an external device over a 2-pin universal asynchronous
receiver/transmitter (UART) or a 4-pin SSI interface. The SSI0 port has the advantage of supporting
higher and more flexible data rates, but it also requires more connections to the CC13xx/CC26xx devices.
The UART0 has the disadvantage of having slightly lower and possibly less flexible rates. However, the
UART0 requires fewer pins and can be easily implemented with any standard UART connection. The
serial interface signals are configured to specific DIO’s. These pins are fixed and cannot be reconfigured.
Table 3. CC13x0/CC26x0 and CC13x2/CC26x2 Configuration of Signal Interfaces
Signal
5 × 5 QFN (RHB)
4 × 4 QFN (RSM)
2.7 × 2.7 WCSP
(YFV)
(1)
DIO1
DIO1
DIO1
(1)
DIO0
DIO2
DIO0
DIO10
DIO10
DIO8
DIO10
DIO11
DIO9
DIO7
DIO9
Input with pull-up
DIO9
DIO11
DIO9
DIO11
No pull (output
when selected)
DIO8
DIO12
DIO0
DIO12
Pin Configuration
7 × 7 QFN (RGZ)
UART0 RX
Input with pull-up
DIO2 (DIO12
UART0 TX
No pull (output
when selected)
DIO3 (DIO13
SSI0 CLK
Input with pull-up
SSI0 FSS
Input with pull-up
SSI0 RX
SSI0 TX
)
)
(1) For CC1352x.
3.3
3.3.1
AUX Pins
CC26x2/CC13x2 AUX Pins
There are up to 32 signals (AUXIO0 to AUXIO31) in the sensor controller domain (AUX Domain). These
signals can be routed to specific DIO pins given in Table 4. The signals AUXIO19 to AUXIO26 have
analog capability, but can also be used as digital I/Os. All the other AUXIOn signals are digital only.
Table 4. CC13x2/CC26x2 Pin Mapping
12
DIO
AUX Domain I/O
DIO
AUX Domain I/O
DIO
AUX Domain I/O
DIO30
19
DIO19
30
DIO8
10
DIO29
20
DIO18
31
DIO7
11
DIO28
21
DIO17
1
DIO6
12
DIO27
22
DIO16
2
DIO5
13
DIO26
23
DIO15
3
DIO4
14
DIO25
24
DIO14
4
DIO3
15
DIO24
25
DIO13
5
DIO2
16
DIO23
26
DIO12
6
DIO1
17
DIO22
27
DIO11
7
DIO0
18
DIO21
28
DIO10
8
DIO20
29
DIO9
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3.3.2
CC26x0/CC13x0 AUX Pins
There are up to 16 signals (AUXIO0 to AUXIO15) in the sensor controller domain (AUX). These signals
can be routed to specific pins given in Table 5. AUXIO0 to AUXIO7 have analog capability, but can also
be used as digital I/Os, while AUXIO8 to AUXIO15 are digital only.
Table 5. CC13x0/CC26x0 Pin Mapping
3.4
7 × 7 QFN (RGZ)
5 × 5 QFN (RHB)
WCSP (YFV)
4 × 4 QFN (RSM)
AUX Domain I/O
DIO30
DIO14
DIO29
DIO13
DIO13
1
DIO28
DIO12
DIO12
2
DIO27
DIO11
DIO11
DIO9
3
DIO26
DIO9
DIO9
DIO8
4
DIO25
DIO10
DIO10
DIO7
5
DIO24
DIO8
DIO8
DIO6
6
DIO23
DIO7
DIO7
DIO5
7
DIO7
DIO4
DIO4
DIO2
8
DIO6
DIO3
DIO3
DIO1
9
DIO5
DIO2
DIO2
DIO0
10
DIO4
DIO1
DIO1
11
DIO3
DIO0
DIO0
12
0
DIO2
13
DIO1
14
DIO0
15
JTAG Pins
The on-chip debug support is done through a dedicated cJTAG (IEEE 1149.7) or JTAG (IEEE 1149.1)
interface. The 2-pin cJTAG mode using only TCK and TMS I/O pads is the default configuration after
power up. The 4-pin JTAG uses TCK, TMS, TDI, and TDO.
Table 6. CC26x0/CC13x0 and CC26x2/CC13x2 JTAG Pins
Signal
7 × 7 QFN (RGZ)
5 × 5 QFN (RHB)
WCSP (YFV)
4 × 4 QFN (RSM)
TCK
Pin 25
Pin 14
Pin F2
Pin 14
TMS
Pin 24
Pin 13
Pin E4
Pin 13
TDI
DIO17
DIO6
DIO6
DIO4
TDO
DIO16
DIO5
DIO5
DIO3
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PCB Layout
4
PCB Layout
4.1
Board Stack-Up
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Board stack-up is in the reference design zip file (see Design_Name_mechanical.pdf). Most important is
the distance from the top layer to the ground layer. Deviating from the recommended board stack-up will
change the parasitics and might in some cases lead to a re-design of the filter balun for optimum
performance.
Figure 7. CC1312R Board Stack Up
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4.2
Balun
The important part is to keep the balun as symmetrical as possible with regard to the RF ports. Therefore,
the trace length from the single ended port to each of the RF pins should be equal to achieve best
amplitude and phase balance in the balun. For a good balun PCB layout, see Figure 8. An unbalance in
the balun causes higher harmonic level, especially at the 2nd and 4th harmonic. Another effect of having
an unsymmetrical balun is reduced output power at the single ended side of the balun. Both component
values and component placement is important to achieve best possible symmetry in the balun. Amplitude
imbalance should be maximum 1.5 dB and the phase imbalance maximum 10°.
To ensure proper performance it is important to implement the same layout of the balun, match, and filter
as in the reference design. Changing the placement of these parts might require tuning on the component
values to obtain the desired performance. Tuning requires advanced RF skills and the proper equipment.
There must be an uninterrupted and solid ground plane under all the RF components, stretching from the
antenna and all the way back to the ground vias in the chip exposed ground pad (EGP). There must not
be any traces under the RF path.
Figure 8. CC1312R Balun and LC Filter PCB Layout
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PCB Layout
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LC Filter
The LC filter should be laid out so that crosstalk between the shunt components is minimized. Figure 9
shows three different layouts from worse to best. The advantage with the layout to the right is that the
parasitic inductance in the PCB track (in black) between the shunt capacitor and the series inductor is in
series with the inductor. In the middle figure the parasitic inductance is in series with the shunt capacitor
forming a series LC circuit. The placement of C12, L13, C13, L14, and C14 in Figure 8 shows good design
practice.
If the design cannot use the reference design as is (for example, use of a different component size) the
filter balun will most likely have to be re-tuned. Simulate both the TI reference design and the custom
design using an electromagnetic simulator. The two designs should have the same S21/S22.
Worse
Best
Figure 9. LC Filter PCB Layout Design Guideline
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4.4
Decoupling Capacitors
General rules for decoupling capacitors:
• Ensure decoupling capacitors are on same layer as the active component for best results
• Route power into the decoupling capacitor and then into the active component
• Each decoupling capacitor should have a separate via to ground to minimize noise coupling (see
Figure 10)
• The decoupling capacitor should be placed close to the pin it is supposed decouple (see Figure 6)
• Ground current return path between decoupling capacitor and chip should be short and direct (low
impedance). For details, see Section 4.5.
Supply
Supply
Supply
Supply
Via to GND
Via to GND
Figure 10. Decoupling Capacitors and VIA to Ground
The figure to the right that uses separate vias to ground, has less noise coupling.
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Current Return Path
There should be a solid ground plane from the capacitor ground pad back to the chip. Figure 11 illustrates
this. Failure to follow this may lead to reduced RF performance and higher spurious emission.
Figure 11. Current Return Path
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4.6
DC/DC Regulator
The DCDC components must be placed close to the DCDC_SW pin. The capacitor at the DC/DC
regulator output (DCDC_SW pin) must have a short and direct ground connection to the chip (low
impedance). Keep a solid ground plane from the capacitor ground pad back to the chip as shown for C331
in Figure 12.
Figure 12. CC1312R DC/DC Regulator PCB Layout
4.7
Antenna Matching Components
A pi-network is recommended for antenna impedance matching. The antenna matching components
should be placed as close to the antenna as possible.
4.8
Transmission Lines
Traces in the balun and LC filter are too short to be considered transmission lines, but longer traces, such
as from the LC filter, towards the antenna should have a 50 Ω impedance. TXLine is a free tool for PCB
trace impedance calculations: TXLine Transmission Line Calculator.
4.9
Electromagnetic Simulation
If the design does not follow the reference design (for example, different filter balun component placement
or component size), it is recommended to use Advanced Design System (ADS) or similar to simulate and
then compare the impedances and S-parameters of the custom design with the reference design.
Changes to the filter balun component values might be required if the custom design deviates too much
from the reference design.
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5
Antenna
5.1
Single-Band Antenna
The existing antenna documentation available at TI is mainly orientated towards antennas that operate at
a single frequency. Two antenna selection guides are available: the Antenna Selection Quick Guide and a
comprehensive Antenna Selection Guide. In addition to the documentation, there is a CC-Antenna-DK2
and Antenna Measurements Summary available on TI’s eStore, as well, with complete documentation. All
antenna documentation that is available from TI can be accessed from the Antenna Selection Quick Guide
since it contains hyperlinks to all antenna documentation, antenna measurement reports, and all antenna
reference designs.
It is always advised to include an antenna matching network in order to tune and to reduce the mismatch
losses of the antenna. For a single-band antenna, the recommendation is to always include a pi-match
network prior to the antenna, see Figure 13. Only two of the three footprints/components are required. The
impedance of the antenna will determine if footprint/component ANT1 or ANT3 is used. ANT2 will always
be used and even if the antenna is perfectly matched, then this can just be set as a 0 Ω resistor.
Antenna
ANT2
Radio
ANT1
ANT3
Figure 13. Recommended Antenna PI-Match Network for Single-Band Antennas
5.2
Dual-Band Antenna
The introduction of dual-band operation with advantages of Bluetooth Low Energy combined with longrange advantages of sub-1 GHz sets the need of dual-band antennas. Separate antennas can be used for
each of the bands, but physical space is normally limited on most handheld devices that promote usage of
dual-band antennas. The most popular dual-band configurations are shown below:
• 863-928 MHz & 2.4 GHz
• 433-450 MHz & 2.4 GHz
• 470-510 MHz & 2.4 GHz
For dual-band operation that contains a low-band and a high-band, the antenna pi-match shown in
Figure 13 is not recommended. It is recommended to use an LC, CL match network instead as shown in
Figure 14. The LC part is used to match the high-band and the CL part is used for the low-band.
Therefore, the LC section will be denoted as LHIGH CHIGH and the CL section as CLOW LLOW in order to
identify the components.
Antenna
Lhigh
Clow
Radio
Chigh
Llow
Figure 14. Recommended Antenna Match Network for Dual-Band Antennas
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5.2.1
Dual-Band Antenna Match Example: 863-928 MHz and 2.4 GHz
This example is based on LaunchPad-CC1352P1.
• Assemble LHIGH: 0 Ω and CLOW : 0 Ω; CHIGH: NC and LLOW : NC
• Measure initial impedance with a network analyzer (VNA) at the low-band (868 MHz) and high-band
(2440 MHz)
– 868 MHz: 54 + j30, VSWR: 1.78:1
– 2.44 GHz: 14 - j32, VSWR: 5.05:1 (This is not required at this stage but included for documentation
purposes to note the delta).
• Match the low-band with only the CLOW and LLOW components
– CLOW: 5.6 pF and LLOW: NC; see Figure 15
Figure 15. Matching the Low-Band With CLOW: 5.6 pF and LLOW: NC
•
•
Confirm the low-band is matched by measuring the impedances again:
– 868 MHz: 42 + j2, VSWR: 1.18:1. Good match at the low-band
– 2.44 GHz: 16+j34, VSWR: 5.38:1
Match the high-band with only the CHIGH and LHIGH components
– LHIGH : 2.2 nH and CHIGH: NC; see Figure 16
Figure 16. Matching the High-Band With an Ideal Value of LHIGH: 2.2 nH and CHIGH: NC
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Antenna
•
•
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LHIGH : 2.2 nH was not sufficient when measured and a value of 3.3 nH was used instead. The antenna
match components are based on ideal components with no parasitics. The match is not ideal but the
CHIGH component could not be used due to the impedance position in the Smith chart.
Measure final impedance with a network analyzer (VNA) at the low-band (868 MHz) and high-band
(2440 MHz),
– 868 MHz: 37 + j8, VSWR: 1.36:1 Good match at the low-band
– 2.44 GHz: 16+j8, VSWR: 3.18:1 Reasonable match at the high-band but would prefer VSWR <
2.00:1; see Figure 17 and Figure 18.
Figure 17. Smith Chart With Final Match Values of LHIGH: 3.3 nH and CLOW: 5.6 pF
Figure 18. VSWR Chart With Final Match Values of LHIGH: 3.3 nH and CLOW: 5.6 pF
•
With the matching components, the antenna match was improved by:
– 868 MHz: VSWR: 1.78:1 –> 1.36:1
– 2.44 GHz: VSWR: 5.05:1 –> 3.18:1
The example shown above used a low-band of 868 MHz but a main requirement of the LaunchPadCC1352P-1 was for good operation for the complete 863 – 928 MHz band since it was important to cover
both ETSI (863-870 MHz) and FCC bands (902-928 MHz). The antenna length on CC1352P1 has a
natural resonance of approximately 900 MHz with no matching components.
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If the performance at 2.44 GHz is more important than supporting both 868 MHz and 915 MHz ISM bands,
then the length of the antenna can be increased so the natural resonance will be around 813 MHz (2440
MHz/3). This would give very good performance at 868 MHz and 2.4 GHz but the 915 MHz band would
suffer. A common antenna match for dual-bands is a compromise of performance between the high-band
and low-band.
5.2.2
Dual-Band Antenna Match: 433-510 MHz and 2.4 GHz
This example is based on LaunchPad-CC1352P-4.
In order to cover the frequency band 433 – 510 MHz, an external component (LANT) is added to the
antenna structure normally used for 863-928 MHz and 2.4 GHz. This is required to keep the antenna
relatively small and to maintain a high efficiency. The LANT component extends the length of the antenna
structure with the extra inductance added. It is difficult to cover the entire frequency band of 433 – 510
MHz with just one BOM due to the wide bandwidth so the frequency range is divided up into the several
regions. An additional antenna structure has also been added that also extends the length of the standard
antenna. This makes the 2.4 GHz matching easier since this is more differentiated than just one antenna
element structure, see Figure 19.
Value of LANT component for 433-510 MHz operation:
• 51 nH: 433 MHz
• 39 nH: 470 MHz
• 33 nH: 490 MHz
433-510 MHz
2.4 GHz
Lant
Lhigh
Clow
Radio
Chigh
Llow
Figure 19. Recommended Antenna Match Network for Dual-Band Antennas (433-510 MHz & 2.4 GHz)
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Once the LANT component has been chosen then the matching procedure is similar as shown in the
previous example. After the antenna matching process, the final values of the antenna match components
can be fixed. As can be seen in Figure 20, the matching of 490 MHz and 2.4 GHz are both below VSWR
1.90 :1, which are good results.
Figure 20. VSWR Chart With Final Match Values of LANT: 33 nH LHIGH: 3.9 nH and CLOW: 0 Ω
Matching the antenna should be performed in the final casing of the product including all surrounding
components such as batteries, displays, and so forth. Casing can affect the antenna’s resonance even if
the material choice is plastic. The positioning of the antenna or body effects will also affect the antenna’s
resonance. The antenna is always detuned by a shift downwards in frequency. Therefore, if there are two
different environments for the antenna such as handheld and stand-alone on a wooden desk, then it is
preferable to have the stand-alone resonance slightly higher so the antenna’s bandwidth can be utilized
when detuned by body effects/metal objects, and so forth.
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6
Crystal Tuning
6.1
CC13xx/CC26xx Crystal Oscillators
The CC13xx/CC26xx devices have two crystal oscillators as shown in Figure 21. The high frequency
crystal oscillator (HFXOSC), running at 24 MHz for CC13x0/CC26x0 and 48 MHz for CC13x2/CC26x2, is
mandatory to operate the radio. The low frequency crystal oscillator (LFXOSC) is used for RTC timing and
only required when accurate RTC timing is necessary, for example for synchronous protocols such as
Bluetooth Low Energy.
U1A
24
25
35
33
4
5
Y1
C41
12pF
32.768kHz
C51
12pF
23
49
JTAG_TMSC
JTAG_TCKC
RESET_N
VDDS2
VDDS3
VDDS
VDDS_DCDC
VDDR
VDDR_RF
DCDC_SW
X32K_Q1
X32K_Q2
RF_P
RF_N
RX_TX
DCOUPL
EGP
X48M_N
X48M_P
13
22
44
34
45
48
1
2
3
46
47
Y2
48MHz
CC1312R1F3RGZ
1
3
2
4
Figure 21. CC1312R With 32 kHz and 48 MHz Crystals
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Crystal Tuning
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Both crystal oscillators are pierce type oscillators that can be seen in Figure 22. In this type of oscillator,
the crystal and the load capacitors form a pi-filter providing a 180° phase shift to the internal amplifier
keeping the oscillator locked at the specified frequency. For this frequency to be correct, the load
capacitance must be dimensioned properly based on the crystal´s capacitive load (CL) parameter.
U1
R1
CL1
CL2
Figure 22. Pierce Type Oscillator
A key difference between the oscillators is that the high frequency oscillator has internal variable load
capacitance inside the IC and does in most cases not require external load capacitors. For details on
when it is required to use external capacitors instead of the internal variable load capacitance, see
Section 3.1.1. The low frequency oscillator on the other hand needs to have external capacitors to operate
properly.
6.2
Crystal Selection
When selecting a crystal part, it is important to look at the device-specific CC13xx/CC26xx data sheets
that lists requirements for the crystal parameters. All of these requirements must be fulfilled to ensure
proper operation of the oscillator(s) and proper operation of the device.
6.3
Tuning the LF Crystal Oscillator
The frequency of the 32-kHz crystal oscillator is set by properly dimensioning the load capacitors relative
to the crystal´s wanted load capacitance, CL. From the crystal´s point of view, the two capacitors are
placed in series, which means that the “resistor parallel” equation to calculate the resulting total
capacitance must be used. Also keep in mind that the PCB traces and the pads add some parasitic
capacitance. Equation 2 shows how to calculate the right load capacitance value.
CL
C1u C2
load capacitor value
C parasitic |
C1 C2
2
C parasitic
(2)
The last simplification requires that C1 and C2 are equal.
The best way to measure the frequency accuracy of the oscillator is to output the clock signal on an I/O
pin. This way the frequency can be measured using a frequency counter without affecting the oscillator.
The following Driverlib calls will output the selected 32-kHz clock source in all power states except
Shutdown:
#include <driverlib/aon_ioc.h>
IOCPortConfigureSet(IOIDn, IOC_PORT_AON_CLK32K, IOC_STD_OUTPUT);
AONIOC32kHzOutputEnable();
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6.4
Tuning the HF Oscillator
The HF oscillator has internal variable load capacitors (cap-array) in the IC and does not require external
capacitors to be mounted. There are some exceptions. For details on when it is required to use external
capacitors instead of the internal cap-array, see Section 3.1.1.
The load capacitance is set in CCFG.c through the following defines:
#ifndef SET_CCFG_MODE_CONF_XOSC_CAP_MOD
// #define SET_CCFG_MODE_CONF_XOSC_CAP_MOD
#define SET_CCFG_MODE_CONF_XOSC_CAP_MOD
#endif
0x0
0x1
// Apply cap-array delta
// Don't apply cap-array delta
#ifndef SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA
#define SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA
0xFF
bit value, directly modifying trimmed XOSC cap-array value
#endif
// Signed 8-
The SET_CCFG_MODE_CONF_XOSC_CAP_MOD defines tells the system whether it should use the
default value or use an offset from the default value set by
SET_CCFG_MODE_CONF_XOSC_CAPARRAY_DELTA. The default cap-array values are 9 pF for
CC13x0/CC26x0 QFN, 5 pF for CC2640R2F WCSP, and 6.7 pF for CC13x2/CC26x2.
The cap-array delta value is an offset from the default value that can be either negative or positive.
Table 7 shows the resulting total capacitance measured on an evaluation board versus cap-array delta
values. Note that the resulting capacitance value includes parasitic capacitances, which is why the lowest
setting is not 0 pF. Using a delta value equal to or lower than the most negative value in the table
completely disables the internal load capacitor array.
The best way to measure the accuracy of the HF crystal oscillator is to output an unmodulated carrier
wave from the radio and measuring the frequency offset from the wanted frequency using a spectrum
analyzer. The relative offset of crystal frequency, typically stated in Parts per Million (ppm), is the same as
the relative offset of the RF carrier.
For testing purposes cap-array delta values can be adjusted in SmartRF™ Studio. This simplifies tuning
greatly by allowing on-the-fly updates of the load capacitance. The optimum value found in SmartRF
Studio can then be entered into CCFG in the applicable software project.
Table 7. Cap-Array Delta
Measured Capacitance on
Reference Board
CCFG Delta Value for
CC13x0/CC26x0 QFN
CCFG Delta Value for
CC2640R2F WCSP
CCFG Delta Value for
CC13x2/CC26x2 QFN
2,1
< -55
< -28
< -40
2,1
-55
-28
-40
2,2
-54
-27
-39
2,3
-53
-26
-38
2,4
-52
-25
-37
2,5
-51
-24
-36
2,6
-50
-23
-35
2,7
-49
-22
-34
2,7
-48
-21
-33
2,8
-47
-20
-32
2,9
-46
-19
-31
3,0
-45
-18
-30
3,1
-44
-17
-29
3,2
-43
-16
-28
3,3
-42
-15
-27
3,4
-41
-14
-26
3,4
-40
-13
-25
3,6
-38
-12
-24
3,7
-37
-11
-23
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27
Crystal Tuning
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Table 7. Cap-Array Delta (continued)
28
Measured Capacitance on
Reference Board
CCFG Delta Value for
CC13x0/CC26x0 QFN
CCFG Delta Value for
CC2640R2F WCSP
CCFG Delta Value for
CC13x2/CC26x2 QFN
3,8
-36
-10
-22
3,9
-35
-9
-21
4,0
-34
-8
-20
4,1
-33
-7
-19
4,3
-32
-6
-18
4,4
-31
-5
-17
4,5
-30
-4
-16
4,6
-29
-3
-15
4,7
-28
-2
-14
4,8
-27
-1
-13
5,0
-26
0
-12
5,1
-25
1
-11
5,2
-24
2
-10
5,3
-23
3
-9
5,5
-21
4
-8
5,6
-20
5
-7
5,8
-19
6
-6
5,9
-18
7
-5
6,1
-17
8
-4
6,2
-16
9
-3
6,4
-15
10
-2
6,5
-14
11
-1
6,7
-13
12
0
6,8
-12
13
1
7,0
-11
14
2
7,1
-10
15
3
7,3
-9
16
4
7,4
-8
17
5
7,6
-7
18
6
7,7
-6
19
7
7,9
-5
21
8
8,2
-4
22
9
8,4
-3
23
10
8,6
-2
24
11
8,8
-1
25
12
9,0
0
26
13
9,2
1
27
14
9,4
2
28
15
9,6
3
29
16
9,8
4
30
17
10,1
5
31
18
10,3
6
32
19
10,5
7
33
20
10,7
8
34
21
10,9
9
35
22
11,1
10
36
23
11,1
> 10
> 36
> 23
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Integrated Passive Component (IPC)
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7
Integrated Passive Component (IPC)
An Integrated Passive Component (IPC) is a matched-filter balun component specially designed or
matched to the RF section. The IPC reduces the component count that saves space and reduces pickand-place assembly costs. In addition, there is less risk of a poor RF layout with an IPC since the RF
crosstalk is minimized. Table 8 lists the available IPC’s.
Table 8. Available IPC’s
Chip Family
Frequency (MHz)
Vendor
Part Number
Application Report
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
430 - 435
Johanson Technology
0433BM15A0001
SWRA520
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
430 - 435
Johanson Technology
0433BM15A0001E-AEC*1
SWRA520
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
863 - 873
Johanson Technology
0868BM15C0001
SWRA520
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
863 - 873
Johanson Technology
0868BM15C0001E-AEC*1
SWRA520
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
863 - 928
Johanson Technology
0896BM15A0001
SWRA520
CC1120, CC1121,
CC1175, CC1200,
CC1201
863 - 928
Johanson Technology
0900PC15J0013
SWRA407
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
902 - 928
Johanson Technology
0915BM15A0001
SWRA297
CC1101, CC1111,
CC1110, CC110L,
CC113L, CC115L, CC430
902 - 928
Johanson Technology
0915BM15A0001E-AEC*1
SWRA297
CC13xx
430-510
Walsin
RFBLN2520090YC3T10
SWRA524
CC13xx
770-928
Murata
LFB18868MBG9E212
SWRA524
CC13xx
770-928
Johanson Technology
0850BM14E0016
SWRA524
CC1352R, CC1352P
863 – 928
2400 - 2480
Murata
LFB21868MDZ5E757
SWRA629
CC1352R, CC1352P
863 – 928
2400 - 2480
Johanson Technology
0900PC15A0036
SWRA629
CC2420
2400 - 2480
Anaren
BD2425N50200A00
SWRA155
CC2430
2400 - 2480
Anaren
BD2425N50200A00
SWRA156
CC2430, CC2480
2400 - 2480
Johanson Technology
2450BM15A0001
CC2520
2400 - 2480
Johanson Technology
2450BM15B0002
CC2500, CC2510
2400 - 2480
Johanson Technology
2450BM15B0003
CC26xx
2400 - 2480
Murata
LFB182G45BG5D920
Johanson Technology
2450BM14G0011
SWRA572
Johanson Technology
2450BM14G0011T-AEC*1
SWRA572
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Optimum Load Impedance
8
www.ti.com
Optimum Load Impedance
CC13xx/CC26xx supports several front-end configurations, both differential and single-ended operation
with either internal or external bias. The different RF front-end configurations are presented in more details
in Section 2. TI offers several reference designs for CC13xx/CC26xx showing recommendations for the
different RF front-end configuration. Note that the different RF front-end configurations from the different
reference designs do not follow the package sizes (7x7 mm, 5x5 mm and 4x4 mm) and can be mixed as
wanted.
CC13xx/CC26xx impedance changes with the state of the chip (TX/RX) and the output/input signal level.
When operated in receive, the LNA gain is adjusted according to the input signal level and is thus not
constant. This results in that the LNA operates with different configuration for the different gain setting.
The PA impedance is further different from the receive impedance. It changes with the configured output
power level and is not linear. The term output impedance is used for linear amplifiers or amplifiers that can
be approximated by a linear equivalent. Output impedance is normally used to design complex conjugate
impedance matching between amplifier and load. For linear amplifiers this is sufficient to secure optimum
power transfer. This method is thus not valid for the CC13xx/CC26xx series.
CC13xx/CC26xx operations are heavily dependent upon filter-balun impedance up to at least the forth
harmonic for sub-1 GHz and up to at least the third harmonic for 2.4 GHz. Matching load impedance only
at fundamental frequency could easily result in high current consumption, low output power and high
spurious/harmonics.
To get the optimal performance with a CC13xx/CC26xx design, it is highly recommended to follow the
reference designs (schematic, layout and stack-up). TI have found the recommended balun and matching
circuits through simulations and load- and source-pull measurements over the full operational range. The
RF circuits are designed to give best overall TX and RX performance (output power, sensitivity, current
consumption, and harmonic and spurious emission).
Note that impedance calculated based on analyzing the data sheet and reference design schematic often
deviate from the optimum load impedance given by TI. PCB parasitic and component imperfections
generally accounts for these differences. When operating at high frequencies, PCB traces have to be
modeled to account for phase shift, skin effect increased resistance, inductive and capacitive effects.
Manufacturers of passives normally provide linear LCR models and/or S-parameter models representing
their components at higher frequencies. Be aware to check the valid frequency range for the models, and
only use them within this range. Simulators often extrapolate the model data without warnings and
simulation results become invalid. Remember that valid frequency range is the range up to the highest
significant frequency component within your circuit.
There are designs that cannot use the reference design as is (for example, use of a different component
size). In this case, it is recommended to simulate both the TI reference design and the customer design in
ADS. The two designs should have the same S21/ S22.
CC26xx
• Differential External Bias target load impedance: 45 + j43 Ω
• Differential Internal Bias target load impedance: 42 + j21 Ω
• Single-ended Internal Bias target load impedance: 38 + j5 Ω
CC1310, CC1312
• 863-928 MHz
– 868 MHz target load impedance: 40 + j15 Ω
• 2440 MHz target load impedance: 25 – j10 Ω
CC1352R, CC1352P
• 863-928 MHz
– 898 MHz Tx/Rx target load impedance: 37-j8 Ω
– 898 MHz Rx only optimized target load impedance: 47+j1 Ω
• 2450 MHz target load impedance: 33+j11 Ω
• 2440 MHz high power PA target load impedance: 200 Ω
• 863-928 MHz high power PA target load impedance: 200 Ω
30
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Power Supply Configuration
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9
Power Supply Configuration
9.1
Introduction
The CC13xx/CC26xx devices have three power rails that are exposed on external pins: VDDS, VDDR and
DCOUPL. VDDS is the main power source for the wireless microcontroller and must be supplied externally
with 1.8 V to 3.8 V. VDDR is an internal power rail that is supplied from the internal DC/DC converter, or
the internal Global LDO, but can be powered from an external supply. VDDR is regulated to approximately
1.68 V, or 1.95 V when running in boost mode for maximum output power in sub-1 GHz bands. In boost
mode, a minimum VDDS voltage of 2.1 V is required. DCOUPL is supplied internally by either Digital LDO
or Micro LDO depending on the power state. This power rail is trimmed to approximately 1.28 V and
requires an external decoupling capacitor of 1 µF.
9.2
DC/DC Converter Mode
CDEC
VDDS
POR / BOD / Misc
1.8 to 3.6 V
VDDS
Global LDO
IOs
Digital LDO
VDD
VDDS2
CDEC
CBULK
IOs
CDEC
Micro LDO
VDDS3
CDEC
IOs
VDDS_DCDC
AON_VD
DCDC_SW
DC/DC Converter
1.68 to 1.95 V
VDDR
MCU_VD
LDCDC
CDEC
VDDR
CBULK
CDEC
VDDR_RF
Oscillators
RF LDOs
CDEC/BULK
DCOUPL
1.28 V
Figure 23. DC/DC Mode
Maximum efficiency is obtained by using the internal DC/DC converter, and it requires an external inductor
(LDCDC) and capacitor (CDCDC). The components should be placed as close as possible to the
CC13xx/CC26xx device and it is important to have a short current return path for from the CDCDC ground
to the pad on the chip (see Section 4.6). In addition, the bulk capacitor on VDDS should be placed close
to the VDDS_DCDC-pin. The actual value of LDCDC, CDCDC and CBULK vary from device to device.
For the actual values, see the device-specific reference design.
When operating in DC/DC mode, the power system dynamically switches between the Global LDO and
DC/DC converter depending on the required load to achieve maximum efficiency. If VDDS drops below
2.0 V, the DC/DC converter will be less efficient than the LDO and the device will run in global LDO mode.
For systems operating with VDDS less than 2.0 V, consider either global LDO or external regulator mode
to save component cost and board area.
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Power Supply Configuration
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The following software setup is required in the CCFG to use the DC/DC converter:
#ifndef SET_CCFG_MODE_CONF_DCDC_RECHARGE
#define SET_CCFG_MODE_CONF_DCDC_RECHARGE
// #define SET_CCFG_MODE_CONF_DCDC_RECHARGE
powerdown
#endif
#ifndef SET_CCFG_MODE_CONF_DCDC_ACTIVE
#define SET_CCFG_MODE_CONF_DCDC_ACTIVE
// #define SET_CCFG_MODE_CONF_DCDC_ACTIVE
#endif
9.3
0x0
0x1
// Use the DC/DC during recharge in powerdown
// Do not use the DC/DC during recharge in
0x0
0x1
// Use the DC/DC during active mode
// Do not use the DC/DC during active mode
Global LDO Mode
CDEC
VDDS
POR / BOD / Misc
1.8 to 3.6 V
VDDS
Global LDO
IOs
Digital LDO
VDD
VDDS2
CDEC
CBULK
IOs
CDEC
Micro LDO
VDDS3
CDEC
IOs
VDDS_DCDC
AON_VD
DCDC_SW
DC/DC Converter
No Correct
1.68 to 1.95 V
MCU_VD
VDDR
VDDR
CBULK
CDEC
CDEC
VDDR_RF
Oscillators
RF LDOs
CDEC/BULK
DCOUPL
~1.28 V
Figure 24. Global LDO Mode
To save cost and PCB area the DC/DC inductor can be removed and VDDR can be supplied from the
Global LDO at the cost of higher power consumption. In this mode a bulk capacitor on VDDR is still
required and should be placed close to the VDDR pin. The VDDS_DCDC-pin must be connected to VDDS
and the DCDC_SW should be left floating to avoid short circuiting VDDS if the DC/DC converter is
mistakenly enabled from software. The VDDS bulk capacitor does not need to be close to the
VDDS_DCDC pin and should rather be placed close to the VDDS pin.
32
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Power Supply Configuration
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The following software setup is required in the CCFG to disable the DC/DC converter and supply VDDR
from Global LDO:
#ifndef SET_CCFG_MODE_CONF_DCDC_RECHARGE
// #define SET_CCFG_MODE_CONF_DCDC_RECHARGE
powerdown
#define SET_CCFG_MODE_CONF_DCDC_RECHARGE
powerdown
#endif
#ifndef SET_CCFG_MODE_CONF_DCDC_ACTIVE
// #define SET_CCFG_MODE_CONF_DCDC_ACTIVE
#define SET_CCFG_MODE_CONF_DCDC_ACTIVE
#endif
9.4
0x0
// Use the DC/DC during recharge in
0x1
// Do not use the DC/DC during recharge in
0x0
0x1
// Use the DC/DC during active mode
// Do not use the DC/DC during active mode
External Regulator Mode
CDEC
VDDS
POR / BOD / Misc
1.68 to 1.95 V
VDDS
Global LDO
IOs
Digital LDO
VDD
CBULK
VDDS2
CDEC
IOs
Micro LDO
VDDS3
CDEC
IOs
VDDS_DCD
C
AON_VD
DCDC_SW
DC/DC Converter
MCU_VD
VDDR
CDEC
CDEC
VDDR_RF
Oscillators
RF LDOs
CDEC/BULK
DCOUPL
~1.28 V
Figure 25. External Regulator Mode
In external regulator mode, neither the Global LDO nor the DC/DC is active and both VDDS and VDDR
must be powered from the same rail. The regulators are disabled by connecting VDDS_DCDC to ground.
Note that the maximum voltage level on the external regulator is limited by VDDR and should not exceed
the absolute maximum rating defined in the device-specific data sheet. To achieve maximum output power
for the sub-1 GHz PA, the supply voltage should be set to 1.95 V.
NOTE: External Regulator Mode is only supported on CC26x0 devices.
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Board Bring-Up
10
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Board Bring-Up
Before starting to develop software or doing range testing, It is recommended to do conducted
measurements to verify that the board has the expected performance. Typically, the sensitivity, output
power, harmonics, and current consumption should be measured to verify the hardware design.
The required measurements depend on the type of board and application. If it is a design with 10 m range
requirement the checkout does not need to be as detailed as for a design with a range extender. For the
latter, and other designs that require high performance, having access to a spectrum analyzer and a
signal generator with the option to send RF packets is highly recommended.
Different measurement methods are discussed in the following sections. It is up to the reader to select the
methods applicable for their board.
10.1 Power On
When powering on the board for the first time, check that the voltages on the following pins are as
expected.
CC13xx and CC26xx
• VDDR = 1.68 V for CCFG_FORCE_VDDR_HH = 0
• VDDR = 1.95 V for CCFG_FORCE_VDDR_HH = 1
• DCOUPL = 1.27 V
Do NOT measure directly on the X24M_P and X24M_N nor X48M_P and X48M_N pins since this could
brick the device.
10.2 RF Test: SmartRF Studio
In order to use SmartRF Studio for testing, the board needs a connector that enables a debugger to be
connected directly to the RF chip:
• For the CC13xx and CC26xx, an XDS100v3, XDS110 or XDS200 should be used.
The required pins in cJTAG-mode are VDDS, GND, RESET, TCK and TMS.
1. Connect a debugger to the board. Open SmartRF Studio and verify that the device is visible in the list
of connected devices.
2. Place two good known boards with 2 m distance. In this context “good known boards“ are EM’s or
LaunchPads from TI. Use a predefined PHY setting in SmartRF Studio that is a closest match to the
PHY that will be used in the final product
3. Set one board to PacketRX and the other to PacketTX and transmit 100 packets. Confirm that the
packets are received and note the RSSI for the received packets.
4. Replace the board used in TX with the device under test (DUT). Repeat the test described in 3.
5. Replace the board used in RX with the DUT. Replace the board used in TX with a good known board.
Repeat the test described in 3.
6. If possible, the measurements should be done with a good known antenna first and then repeated with
the antenna that is going to be used in the final design later. A poorly tuned antenna could cause a
significant loss in sensitivity/output power.
7. If the results are satisfactory, change the settings from the predefined setting to the RF settings
planned to be used in the final product. Repeat the tests described in 3 to 5 with the wanted RF
settings.
If the RSSI deviates from the reference, the schematic and layout should be reviewed. Note that if the
network between the RF ports and the antenna on the customer board is different from the TI evaluation
board, the losses due to SAW filters and switches must be to be taken into consideration.
10.3 RF Test: Conducted Measurements
For high performance designs it is highly recommended to perform conducted measurements to verify the
performance before setting up an RF link.
34
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Board Bring-Up
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10.3.1
Sensitivity
1. Disconnect the antenna and perform conducted measurements at the SMA connector or solder a semi
rigid coax cable at the 50 Ω point.
2. Configure the board under test and use the PacketRX option in SmartRF Studio similar to the test
described in Section 10.2. In PacketRX mode, you can set an expected packet count.
3. Preferred: Use a signal generator that is capable of transmitting data packets. Remember to set up the
sync word and CRC correctly.
4. If a signal generator is not available, use an EM/LaunchPad as a transmitter. Use coax cables and
attenuation between the EM/LauncPad SMA connector and the 50 Ω point on the custom board.
NOTE: It is difficult to get an accurate number using this method since the exact values of output
power and attenuation are normally not known. Some energy will also travel over the air from
the EM to the DUT. In addition, background noise could impact the results. To get more
accurate results, the receiver should be placed in a shielded box.
5. SmartRF Studio will calculate the packet error rate (PER) and bit error rate (BER).
If the wanted RF settings are different from the predefined setting, PER vs level should be run in addition.
The input power level should be increased in 1- 2 dB steps from the sensitivity limit to around 0 dBm. For
each power level, transmit at least 100 packets and record the PER. If the AGC settings are not optimal it
is common that the PER for some of the steps will be above 0 (residual PER) and if that is the case the
AGC settings have to be reviewed.
If the conducted sensitivity is poor:
• Are the settings the same as the recommended values from SmartRF Studio? If the sensitivity is good
when using SmartRF Studio and not with the settings used for the project the settings have to be
reviewed.
• What is the frequency difference between the DUT and the signal source? Frequency offset can be
measured by transmitting an un-modulated continuous wave
• Is the schematic, including all component values, in accordance with the reference design?
• Is the layout in accordance with the reference design?
10.3.2
Output Power
1. Disconnect the antenna and perform conducted measurements at the SMA connector or solder a semirigid coax cable at the 50 Ω point.
2. Preferred: Use a spectrum analyzer (SA). Use 1 MHz RBW for measuring output power.
3. If an SA is not available use an EM or Launchpad with a SMA connection point. Use coax cables and
attenuation between the EM/LaunchPad SMA connector and the 50 Ω point on the custom board. Use
SmartRF Studio and set the EM/Launchpad in continuous RX and read the RSSI. Note that the RSSI
has a given tolerance so the measurement will not be as accurate as the preferred method.
10.4 Software Bring-Up
For CC13xx:
Basic examples for RF and other drivers can be found under TI Drivers under software -> Examples ->
Development Tools -> <Development board in question> at http://dev.ti.com/tirex/#/. Before starting to
write own software it is recommended to run the RF examples that are closest to the wanted application
unmodified and verify that they work. Then, if required, change the RF settings to the wanted data rate,
and so forth.
For CC26xx and Bluetooth Low Energy:
For more information, see Initial Board Bring Up on recommended software images to run initially.
Basic examples for RF and other drivers can be found under TI Drivers under software -> Examples ->
Development Tools -> <Development board in question> at http://dev.ti.com/tirex/#/.
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35
Board Bring-Up
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10.5 Hardware Troubleshooting
This section covers some of the common causes for poor performance.
10.5.1
No Link: RF Settings
To get a link between two RF chips the two RF chips have to operate on the same frequency and with the
same RF settings. This means that the two have to use the same data rate, deviation and modulation
format. A common mistake is that the sync word has been set differently on the two devices, they have to
be equal.
10.5.2
No Link: Frequency Offset
For narrow band systems a too large frequency offset between the TX and RX devices could result in no
link or a very poor link.
The minimum required RX bandwidth to ensure reception is given by:
RX BW = Signal Bandwidth + 4*ppm Crystal * RF Frequency of Operation
(3)
For FSK the signal bandwidth can be approximated as data rate + 2*frequency deviation (Carson’s rule).
For CC13x0: For low data rates, the bit repetition patch CC13x0 Low Data Rate Operation should be
used. If this patch is not used, the frequency offset tolerance could be under 10 ppm, which could cause
loss of link with a normal crystal tolerance.
10.5.3
Poor Link: Antenna
An antenna needs a matching network in order to tune and reduce the mismatch losses of the antenna. If
the antenna is not tuned, energy will be lost both in TX and RX and the link budget will be lower. For more
details, see Section 5.
10.5.4
Bluetooth Low Energy: Device Does Advertising But Can Not Connect
If using the 32 kHz crystal oscillator as RTC source:
• Incorrect load capacitors for the 32.768 kHz crystal – causes frequency offset
• 32 kHz crystal does not start up (incorrect load capacitors, crystal missing, soldering issues) – the
device defaults to run the RTC from the 48 MHz RC oscillator at 31.25 kHz. For more information, see
the PRCM chapter in the CC13x0, CC26x0 SimpleLink™ Wireless MCU Technical Reference Manual
and the C13x2, CC26x2 SimpleLink™ Wireless MCU Technical Reference Manual.
If using the 32 kHz RC oscillator as RTC source:
• Calibration is not configured correctly. For more information, see the Bluetooth Low Energy Stack
User's Guide that is provided with the SDK.
Incorrect RTC frequency will lead to the device missing the connection events and thus breaking the link
with the central device.
To debug this problem, the 32 kHz clock can be output on an I/O pin and measured with a frequency
counter. For more information on how to do this, see the I/O chapter in the CC13x0, CC26x0 SimpleLink™
Wireless MCU Technical Reference Manual and the C13x2, CC26x2 SimpleLink™ Wireless MCU
Technical Reference Manual. By outputting the clock on a pin, you will always measure the _selected_
RTC clock source, as well as be able to measure without affecting the clock source (which probing the
crystal for example will do).
If using a 32.768 kHz crystal make sure the crystal part is within the requirements outlined in the devicespecific CC13xx/CC26xx data sheets. Also make sure that the load capacitors are dimensioned properly
as shown in Section 6.3.
Verify that the BLE-Stack has been configured with the correct Sleep Clock Accuracy. The default setting
is 40 ppm and can be adjusted with the HCI_EXT_SetSCACmd API, see hci.h or the TI Vendor Specific
API Guide included in the SDK.
36
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References
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10.5.5
Poor Sensitivity: DCDC Layout
It is highly recommended to follow the reference design when it comes to the components connected to
the DCDC_SW pin. The shunt capacitor following the series inductor from the DCDC_SW pin has to have
a short return path to chip ground from the ground pad (see Section 4.6). A poor DCDC layout could
cause more than 5 dB loss in sensitivity. To check if the sensitivity is limited by the DCDC, turn off the
DCDC in the CCFG.c file.
10.5.6
•
•
•
•
•
11
High Sleep Power Consumption
Note that the chip is not going into the lowest power modes when a debugger is connected
Software: Use the pinStandby or pinShutdown examples in the relevant SDK
When measuring current draw on a Launchpad, remove all jumpers.
Ensure that every IC on the board is powered down.
If the application is configured to use the 32 kHz crystal (set in CCFG.c), check that this is connected
and that the oscillator is running.
References
•
•
•
•
•
•
•
•
•
•
•
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•
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TXLine Transmission Line Calculator
Texas Instruments: Antenna Selection Quick Guide
Texas Instruments: Antenna Selection Guide
CC-Antenna-DK2
Texas Instruments: CC-Antenna-DK2 and Antenna Measurements Summary
Texas Instruments: CC13x0 Low Data Rate Operation
Texas Instruments: Monopole PCB Antenna with Single or Dual Band Option
Texas Instruments: LAUNCHXL-CC1310 Design Files
Texas Instruments: SimpleLink Sub-1 GHz CC1312R Wireless (MCU) LaunchPad Dev Kit
868MHz/915MHz App
Texas Instruments: 2.4-GHz Inverted F Antenna
Texas Instruments: LAUNCHXL-CC2640R2 Design Files
Texas Instruments: CC26x2R LaunchPad Design Files
Texas Instruments: Miniature Helical PCB Antenna for 868 MHz or 915/920 MHz
Texas Instruments: LAUNCHXL-CC1350 Design Files
Texas Instruments: Monopole PCB Antenna with Single or Dual Band Option
Texas Instruments: 2.4-GHz Inverted F Antenna
Texas Instruments: CC1352R LaunchPad Design Files
Texas Instruments: LAUNCHXL-CC1352P-2 Design Files
Texas Instruments: LAUNCHXL-CC1352P-4 Design Files
Texas Instruments: CC1350STK Design Files
Texas Instruments: CC1125 BoosterPack™ for 868/915 MHz BOOSTXL-CC1125
Texas Instruments: Matched Integrated Passive Component for 868 / 915 MHz operation with the
CC112x, CC117x & CC12xx high performance radio series
Texas Instruments: Johanson Technology, Inc. Highly temperature-stable Impedance Matched RF
Front End Differential Balun-Band Pass Filter Integrated Ceramic Component
Texas Instruments: CC1310 Integrated Passive Component for 779-928 MHz
Texas Instruments: Matched Filter Balun for CC1352 and CC1352P
Texas Instruments: Anaren 0404 (BD2425N50200A00) balun optimized for Texas Instruments CC2420
Transceiver
Texas Instruments: Anaren 0404 (BD2425N50200A00) balun optimized for Texas Instruments CC2430
Transceiver
SWRA640C – December 2018 – Revised September 2019 CC13xx/CC26xx Hardware Configuration and PCB Design Considerations
Submit Documentation Feedback
Copyright © 2018–2019, Texas Instruments Incorporated
37
References
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www.ti.com
Texas Instruments: Johanson Balun for the CC26xx Device Family
Texas Instruments: CC13x0, CC26x0 SimpleLink™ Wireless MCU Technical Reference Manual
Texas Instruments: C13x2, CC26x2 SimpleLink™ Wireless MCU Technical Reference Manual
CC13xx/CC26xx Hardware Configuration and PCB Design Considerations SWRA640C – December 2018 – Revised September 2019
Submit Documentation Feedback
Copyright © 2018–2019, Texas Instruments Incorporated
Revision History
www.ti.com
Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from B Revision (July 2019) to C Revision ..................................................................................................... Page
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Updates were made in Table 1. ......................................................................................................... 6
Updates were made in Section 2.1. .................................................................................................... 7
Updates were made in Section 7 ...................................................................................................... 29
SWRA640C – December 2018 – Revised September 2019
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Copyright © 2018–2019, Texas Instruments Incorporated
Revision History
39
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