Texas Instruments | AN086 -- Using CC2591 Front End with CC2530 and CC2531 (Rev. A) | Application notes | Texas Instruments AN086 -- Using CC2591 Front End with CC2530 and CC2531 (Rev. A) Application notes

Texas Instruments AN086 -- Using CC2591 Front End with CC2530 and CC2531 (Rev. A) Application notes
Application Note AN086
Using CC2591 Front End with CC2530/1
By Espen Slette and Michael Paszowski
Keywords
•
•
•
•
1
•
•
•
•
2.4 GHz IEEE 802.15.4 systems
ZigBee® systems
Range Extender
External PA
External LNA
CC2530
CC2531
CC2591
Introduction
The CC2530 is TI's second generation
ZigBee® / IEEE 802.15.4 RF System-onChip (SoC) for the 2.4 GHz unlicensed
ISM band. This chip enables industrial
grade applications by offering state-of-theart selectivity/co-existence, excellent link
budget, and low voltage operation. The
CC2531 is identical to the CC2530 with
the addition of an USB interface
CC2591 is a range extender for 2.4-GHz
RF transceivers, transmitters and SoC
products from Texas Instruments. CC2591
increases the link budget by providing a
Power Amplifier (PA) for higher output
power and a Low Noise Amplifier (LNA)
for improved receiver sensitivity. CC2591
further contains RF switches, RF
matching, and a balun for a seamless
interface with the CC2530. This allows for
simple design of high performance
wireless applications.
This application note describes how to
implement the CC2530 and the CC2591 in
the same design. It further describes the
expected
performance
from
this
combination as well as important factors to
consider with respect to the layout and
regulatory requirements. The combined
CC2530 and CC2591 solution is suitable
for systems targeting compliance with
FCC CFR47 Part 15.
The RF front end of CC2530 is the same
as the ones being used in CC2531. The
presented results in this application note
are therefore also valid for CC2531.
Texas Instruments ZigBee SW solution, ZStack (www.ti.com/z-stack), includes the
necessary SW changes for using the
CC2591. For details the reader is referred
to the “PA/LNA Service” chapter in the
“HAL Driver API.pdf” document included in
the Z-Stack documents folder.
Page 1 of 19
SWRA308A
Application Note AN086
Table of Contents
KEYWORDS.............................................................................................................................. 1
1
INTRODUCTION............................................................................................................. 1
2
ABBREVIATIONS........................................................................................................... 2
3
ABSOLUTE MAXIMUM RATINGS................................................................................. 3
4
ELECTRICAL SPECIFICATIONS .................................................................................. 3
4.1
OPERATING CONDITIONS ............................................................................................ 3
4.2
CURRENT CONSUMPTION ........................................................................................... 3
4.3
RECEIVE PARAMETERS .............................................................................................. 4
4.4
RECEIVED SIGNAL STRENGTH INDICATOR (RSSI) ........................................................ 4
4.5
TRANSMIT PARAMETERS ............................................................................................ 5
4.6
OUTPUT POWER PROGRAMMING ................................................................................ 5
4.7
TYPICAL PERFORMANCE CURVES ............................................................................... 6
4.8
IEEE - TRANSMIT POWER SPECTRAL DENSITY (PSD) MASK .......................................... 8
5
APPLICATION CIRCUIT ................................................................................................ 9
5.1
POWER DECOUPLING AND RF LOADING ...................................................................... 9
5.2
INPUT/ OUTPUT MATCHING AND FILTERING .................................................................. 9
5.3
BIAS RESISTOR ........................................................................................................ 10
5.4
ANTENNA CONSIDERATIONS ..................................................................................... 10
6
PCB LAYOUT CONSIDERATIONS ............................................................................. 11
6.1
CC2530 – CC2591 STABILITY ................................................................................. 11
6.2
THE GAIN OF THE CC2591....................................................................................... 12
7
REGULATORY REQUIREMENTS ............................................................................... 13
7.1
DUTY CYCLING WHEN COMPLYING WITH FCC............................................................ 14
7.2
COMPLIANCE OF FCC PART 15.247 WHEN USING THE CC2530 WITH THE CC2591 .... 14
8
CONTROLLING THE CC2591 ..................................................................................... 17
9
REFERENCES.............................................................................................................. 19
10
GENERAL INFORMATION .......................................................................................... 19
10.1
DOCUMENT HISTORY................................................................................................ 19
2
Abbreviations
SoC
DSSS
EIRP
EM
EVM
ISM
FCC
FHSS
LNA
PA
PCB
PSD
RF
RSSI
RX
TX
VSWR
System-on-Chip
Direct Sequence Spread Spectrum
Equivalent Isotropically Radiated Power
Evaluation Module
Error Vector Magnitude
Industrial, Scientific, Medical
Federal Communications Commission
Frequency Hopping Spread Spectrum
Low Noise Amplifier
Power Amplifier
Printed Circuit Board
Power Spectral Density
Radio Frequency
Receive Signal Strength Indicator
Receive, Receive Mode
Transmit, Transmit Mode
Voltage Standing Wave Ratio
Page 2 of 19
SWRA308A
Application Note AN086
3
Absolute Maximum Ratings
The absolute maximum ratings and operating conditions listed in the CC2530 datasheet [1]
and the CC2591 datasheet [4] must be followed at all times. Stress exceeding one or more of
these limiting values may cause permanent damage to any of the devices.
4
Electrical Specifications
Note that these characteristics are only valid when using the recommended register settings
presented in Section 4.6 and in Chapter 8, and the CC2530 - CC2591EM reference design.
4.1
Operating Conditions
Parameter
Operating Frequency
Operating Supply Voltage
Operating Temperature
Min
2405
2.0
-40
Max
2483.5
3.6
85
Unit
MHz
V
°C
Table 4.1 Operating Conditions
4.2
Current Consumption
TC = 25°C, VDD = 3.0 V, f = 2440 MHz if nothing else is stated. All parameters are measured
on the CC2530 - CC2591EM reference design [11] with a 50 Ω load.
Parameter
Receive Current
Transmit Current
Power Down Current
Condition
Wait for sync, -90 dBm input level
Wait for sync, -50 dBm input level
TXPOWER = 0xE5
TXPOWER = 0xD5
TXPOWER = 0xC5
TXPOWER = 0xB5
TXPOWER = 0xA5
TXPOWER = 0x95
TXPOWER = 0x85
TXPOWER = 0x75
TXPOWER = 0x65
PM2
Typical
27
24
166
149
138
127
115
100
94
86
79
1
Unit
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
uA
Table 4.2 Current Consumption
Page 3 of 19
SWRA308A
Application Note AN086
4.3
Receive Parameters
TC = 25°C, VDD = 3.0 V, f = 2440 MHz if nothing else is stated. All parameters are measured
on the CC2530 - CC2591EM reference design with a 50 Ω load.
Parameter
Receive Sensitivity HGM
Receive Sensitivity LGM
Saturation
Condition
1 % PER, IEEE 802.15.4 [6] requires -85 dBm
1 % PER, IEEE 802.15.4 [6] requires -85 dBm
IEEE 802.15.4 [6] requires -20 dBm
Typical
-98.8
-90.4
10
Unit
dBm
dBm
dBm
35
49
56
dB
dB
dB
Wanted signal 3 dB above the sensitivity level,
IEEE 802.15.4 modulated interferer at IEEE 802.15.4 channels
Interferer Rejection
±5 MHz from wanted signal, IEEE 802.15.4 [6] requires 0 dB
±10 MHz from wanted signal, IEEE 802.15.4 [6] requires 30 dB
±20 MHz from wanted signal. Wanted signal at -82dBm
Table 4.3 Receive Parameters
4.4
Received Signal Strength Indicator (RSSI)
Due to in the external LNA and the offset in CC2530 the RSSI readouts from CC2530 CC2591 is different from RSSI offset values for a standalone CC2530 design. The offset
values are shown in Table 4.4.
CC2530-CC2591EM LNA mode
High Gain Mode
Low Gain Mode
RSSI offset1
79
67
Table 4.4 RSSI Compensation
1
Real RSSI = Register value – RSSI offset
Page 4 of 19
SWRA308A
Application Note AN086
4.5
Transmit Parameters
TC = 25°C, VDD = 3.0 V, f = 2440 MHz if nothing else is stated. All parameters are measured
on the CC2530 - CC2591EM reference design with a 50 Ω load. Radiated measurements are
done with the kit antenna.
Parameter
Radiated Emission
with TXPOWER = 0xE5
Complies with
FCC 15.247. See
Chapter 7 for more
details about regulatory
requirements and
compliance
Condition
Typical
Unit
Conducted 2·RF (FCC restricted band)
Conducted 3·RF (FCC restricted band)
-46.2
-46.5
dBm
dBm
Radiated 2·RF (FCC restricted band)
-42.2
dBm
IEEE 802.15.4 [6] requires max. 35%
Measured as defined by IEEE 802.15.4 [6]
Max Error Vector
Magnitude (EVM)
TXPOWER = 0xE5, f = IEEE 802.15.4 channels
TXPOWER = 0xD5, f = IEEE 802.15.4 channels
TXPOWER = 0xC5 f = IEEE 802.15.4 channels
TXPOWER = 0xB5 f = IEEE 802.15.4 channels
TXPOWER = 0xA5, f = IEEE 802.15.4 channels
TXPOWER = 0x95, f = IEEE 802.15.4 channels
TXPOWER = 0x85, f = IEEE 802.15.4 channels
TXPOWER = 0x75, f = IEEE 802.15.4 channels
TXPOWER = 0x65, f = IEEE 802.15.4 channels
13
6
4
3
3
3
3
3
2
%
%
%
%
%
%
%
%
%
Table 4.5 Transmit Parameters
4.6
Output Power Programming
The RF output power of the CC2530 - CC2591EM is controlled by the 7-bit value in the
CC2530 TXPOWER register. Table 4.6 shows the typical output power and current
consumption for the recommended power settings. The results are given for TC = 25°C, VDD
= 3.0 V and f = 2440 MHz, and are measured on the CC2530 - CC2591EM reference design
with a 50 Ω load. For recommendations for the remaining CC2530 registers, see Chapter 8 or
use the settings given by SmartRF Studio.
TXPOWER
0xE5
0xD5
0xC5
0xB5
0xA5
0x95
0x85
0x75
0x65
Power [dBm]
20
19
18
17
16
14.5
13
11.5
10
Current [mA]
166
149
138
127
115
100
94
86
79
Table 4.6 Power Table
Note that the recommended power settings given in Table 4.6 are a subset of all the possible
TXPOWER register settings. However, using other settings than those recommended might
Page 5 of 19
SWRA308A
Application Note AN086
result in suboptimal performance in areas like current consumption, EVM, and spurious
emission.
4.7
Typical Performance Curves
TC = 25°C, VDD = 3.0 V, f = 2440 MHz if nothing else is stated. All parameters are measured
on the CC2530 - CC2591EM reference design with a 50 Ω load.
3.6V
3V
2V
Output power (dBm)
22
21
20
19
18
17
16
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
IEEE 802.15.4 channel
Figure 4.1 Output Power vs. Frequency and Power Supply Voltage, TXPOWER = 0xE5
Output power (dBm)
25
20
15
0xE5
0xC5
0xA5
0x85
0x65
10
5
0
-5
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
Temperature (°C)
Figure 4.2 Output Power vs. Temperature
Page 6 of 19
SWRA308A
Application Note AN086
Sensitivity (dBm)
-90
-94
-98
-102
Avg 3.6V
Avg 3V
Avg 2V
-106
-110
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
IEEE 802.15.4 channel
Figure 4.3 Sensitivity vs. Frequency and Power Supply Voltage
Sensitivity (dBm)
-90
-94
-98
-102
3.6V
3V
2V
-106
-110
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
Temperature (°C)
Figure 4.4 Sensitivity vs. Temperature and Power Supply Voltage
70
Selectivity (dB)
60
50
40
30
20
10
Wanted signal at:
-82 dBm
0
-10
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
IEEE 802.15.4 channel offset
Figure 4.5 Selectivity Operating at Channel 18 (2440 MHz)
Page 7 of 19
SWRA308A
RSSI readout
Application Note AN086
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-100
CC2530-CC2591EM High Gain Mode
CC2530-CC2591EM Low Gain Mode
CC2530EM
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Input power (dBm)
Figure 4.6 RSSI Readout vs. Input Power
4.8
IEEE - Transmit power spectral density (PSD) mask
The IEEE standard 802.15.4 [8] requires the transmitted spectral power to be less than the
limits specified in Table 4.7.
Frequency
|f – fc| > 3.5 MHz
Relative limit
-20 dB
Absolute limit
-30 dBm
Table 4.7 Transmit PSD limits
Conducted spectral power (dBm)
The results below are given for TC = 25°C, VDD = 3.0 V and f = 2440 MHz, and are measured
on the CC2530 - CC2591EM reference design with a 50 Ω load.
40
30
20
10
0
-10
-20
-30
-40
-50
-60
2432.5
IEEE absolute
limit
Channel 18
2435
2437.5
2440
2442.5
2445
2447.5
Frequency (MHz)
Figure 4.7 Conducted power spectral density, TXPOWER = 0xE5
Page 8 of 19
SWRA308A
Application Note AN086
5
Application Circuit
TL131
AVDD_LNA
TL101
AVDD_PA2
AVDD_PA1
BIAS
AVDD_BIAS
TL11
Only a few external components are required for the CC2530 - CC2591 reference design. A
typical application circuit is shown below in Figure 5.1. Note that the application circuit figure
does not show how the board layout should be done. The board layout will greatly influence
the RF performance of the CC2530 - CC2591EM. TI provides a compact CC2530 CC2591EM reference design that it is highly recommended to follow. The layout, stack-up
and schematic for the CC2591 need to be copied exactly to obtain good performance. Note
that the reference design also includes bill of materials with manufacturers and part numbers.
Figure 5.1 Application Circuit for the CC2530 with CC2591
5.1
Power Decoupling and RF Loading
Proper power supply decoupling must be used for optimum performance. In Figure 5.1, only
the decoupling components for the CC2591 are shown. This is because, in addition to
decoupling, the parallel capacitors C11, C101, and C131 together with, L101, L102, TL11,
TL101 and TL131 also work as RF loads. These therefore ensure the optimal performance
from the CC2591. C161 decouples the AVDD_BIAS power.
The placement and size of the decoupling components, the power supply filtering and the
PCB transmission lines are very important to achieve the best performance. Details about the
importance of copying the CC2530 - CC2591EM reference design exactly and potential
consequences of changes are explained in chapter 6.
5.2
Input/ Output Matching and Filtering
The RF input/output of CC2530 is high impedance and differential. The CC2591 includes a
balun and a matching network in addition to the PA, LNA and RF switches which makes the
interface to the CC2530 seamless. Only a few components between the CC2530 and
CC2591 necessary for RF matching. For situation with extreme mismatch (VSWR 6:1 till 12:1
out-of-band as shown in Figure 6.2) it is recommended to include all the components as
shown in Figure 5.1.
Page 9 of 19
SWRA308A
Application Note AN086
Note that the PCB transmission lines that connect the two devices also are part of the RF
matching. It is therefore important to copy the distance between the devices, the transmission
lines and the stack-up of the PCB according to the reference design to ensure optimum
performance.
The network between the CC2591 and the antenna (L111, C112, C111 C113 and L112)
matches the CC2591 to a 50 Ω load and provides filtering to pass regulatory demands. C111
also works as a DC-block.
5.3
Bias resistor
R151 is a bias resistor. The bias resistor is used to set an accurate bias current for internal
use in the CC2591.
5.4
Antenna Considerations
The TI reference design contains two antenna options. As default, the SMA connector is
connected to the output of CC2591 through a 0 Ω resistor. This resistor can be soldered off
and rotated 90° clockwise in order to connect to the PCB antenna, which is a planar inverted
F antenna (PIFA). Note that all testing and characterization has been done using the SMA
connector. The PCB antenna has only been functionally tested by establishing a link between
two EMs. Please refer to the antenna selection guide [6] and the Inverted F antenna design
note [7] for further details on the antenna solutions.
Page 10 of 19
SWRA308A
Application Note AN086
6
PCB Layout Considerations
The Texas Instruments reference design uses a 1.6 mm (0.062”) 4-layer PCB solution. Note
that the different layers have different thickness; it is important to follow the recommendation
given in the CC2530 - CC2591EM reference design [11] to ensure optimum performance.
The top layer is used for components and signal routing, and the open areas are filled with
metallization connected to ground using several vias. The areas under the two chips are used
for grounding and must be well connected to the ground plane with multiple vias. Footprint
recommendation for the CC2591 is given in the CC2591 datasheet [4].
Layer two is a complete ground plane and is not used for any routing. This is done to ensure
short return current paths. The low impedance of the ground plane prevents any unwanted
signal coupling between any of the nodes that are decoupled to it. A dedicated ground plane
is also needed to improve stability (see Section 6.1). Layer three is a power plane. The
power plane ensures low impedance traces at radio frequencies and prevents unwanted
radiation from power traces. Layer four is used for routing, and as for layer one, open areas
are filled with metallization connected to ground using several vias.
Important Notice
Changes in the PCB stack-up, component value, vendors, sizes or placements can cause
significant effects on the performance of the combined CC2530 and CC2591 solution. Any
change can cause higher current consumption, oscillations of the CC2591, unwanted
spurious emissions and generally degraded performance. It is strongly advised that the
reference design [3] is followed as closely as possible in order to obtain the best
performance.
6.1
CC2530 – CC2591 Stability
When a common, center ground-pin/paddle is used, all inductance seen between this ground
paddle and the ground plane will give rise to feedback. This feedback might give rise to
oscillations. There is no general rule that tells exactly how much inductance that exists
between the ground paddle and the ground plane – it depends on the chip design. Still, a
general rule of thumb is that chances of oscillations increase when the RF currents increase.
The stability issue is the main reason for using a 4-layer PCB with a ground-plane close to
the top layer of the CC2530 - CC2591EM reference design [11].
It is generally accepted that an antenna is useful only within the bandwidth at which the
VSWR is 2:1 or lower, with 1.5:1 often cited as the maximum acceptable VSWR. The CC2530
- CC2591EM reference design [11] has been tested with two different matching conditions.
One with a 50Ω connection and another that have a mismatch of VSWR 2:1 within the
operating frequency band and the mismatch out of the operating area is between 6:1 and
12:1, see Figure 6.2. The stable regions of the CC2530-CC2591EM is shown in Figure 6.1
where the register setting in the figure show the maximum acceptable power setting and the
mismatch region where the CC2530-CC2591EM is stable.
Figure 6.1 Stability vs. temperature
Page 11 of 19
SWRA308A
VSWR
Application Note AN086
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
50 Ω
Mismatch out-of-band
0.5
1
1.5
2
2.5
3
3.5
4
Frequency (GHz)
Figure 6.2 VSWR
6.2
The Gain of the CC2591
Changing the layout or the stack-up of the reference design [11] affects the gain of the
CC2591. This is because the gain of the CC2591 can be viewed as a function of both the onchip capacitance and impedance and the external impedance contributions. Internal on-chip
routing and capacitance, bond wires (often several in parallel), the PCB transmission lines,
the thermal relieves on the decoupling capacitors’ ground nodes, capacitance and parasitic of
the decoupling capacitors, the inductance of the vias to the ground plane and the soldering of
the chip will therefore contribute to the actual performance of the CC2591. A simplified model
of all of these contributions is shown in Figure 6.3.
Due to all the contributors to the CC2591 performance, several observations can be made on
how changing layout and PCB stack-up affects the amplifier:
•
•
•
Misplacing the decoupling capacitor or using an arbitrary capacitor will change
the inductance, and hence move the resonance frequency of the amplifier, i.e.
the frequency with maximum gain.
Bad soldering of the ground paddle can reduce the gain significantly.
Too few or too long vias will reduce the gain significantly. This is why a
checkered pattern of vias/ solder paste and a 4-layer PCB with the ground plane
close to the top layer has been chosen for the CC2530 - CC2591EM reference
design.
Page 12 of 19
SWRA308A
Application Note AN086
TLINE
Bondwire
V_out
V_in
Bondwire(s),
soldering,
gnd vias
Figure 6.3 Simplified Model of the Impedance Contributors in the CC2591 Design
7
Regulatory Requirements
In the United States, the Federal Communications Commission (FCC) is responsible for the
regulation of all RF devices. CFR 47, Part 15, regulates RF products intended for unlicensed
operation. A product intended for unlicensed operation has to be subject to compliance
testing. If the product is approved, the FCC will issue an identification number.
The specific frequency bands used for unlicensed radio equipment for the 2.4 GHz band are
regulated by section 15.247 and 15.249. General rules for certification measurements are
found in section 15.35. Restricted bands and general limits for spurious emissions are found
in sections 15.205 and 15.209.
The CC2530 - CC2591EM reference design [11] has been tested for compliance with FCC
Part 15.247. While it is not a formal certification, it does give a good representation of
emissions with respect to compliance requirements. The FCC Part 15.247 compliance is
generally a tougher requirement than ETSI compliance (EN 300 328) due to the restricted
bands of operation. There are however requirements with regards to ETSI compliance (EN
300 328) that prevents operation at maximum output power. The clause 4.3.2.2 Maximum
Power Spectral Density requirement of EN 300 328 requires maximum +10 dBm/ 1 MHz. The
output power must therefore be reduced to approximately +12 dBm in order to get CE
approval. The final output power level will depend on the antenna used.
The CC2590 is a pin and function compatible device that is optimized for operation in
systems designed to be ETSI compliant
FCC Part 15.247 limits the output power to 1 W or +30 dBm when Direct Sequence Spread
Spectrum (DSSS) modulation or Frequency Hopping Spread Spectrum (FHSS) with at least
75 hop channels is used. The spectral density of digital modulation systems (not including
FHSS) shall not exceed 8 dBm/ 3 kHz. The minimum 6 dB bandwidth of such systems is 500
kHz. Since the CC2530 is an IEEE 802.15.4 compliant transceiver, it uses DSSS modulation.
The +30 dBm limit therefore apply for the CC2530 with the CC2591 combination.
Page 13 of 19
SWRA308A
Application Note AN086
When complying with Part 15.247, in any 100 kHz bandwidth outside the operating band, the
power level shall be at least 20 dB below the level in the 100 kHz bandwidth with the highest
power level in the operating band. Attenuation below limits given in 15.209 is not required.
Emission that fall within restricted bands (15.205) must meet general limits given in 15.209.
This is summarized in Table 7.1 below. More details about the 2.4 GHz FCC regulations are
found in application note AN032 [9].
Standard
Relevant Frequency
Radiated
Power
(EIRP)
2400 – 2483.5 MHz
FCC 15.247
Restricted bands
defined by 15.205,
including the 2nd, 3rd
and 5th harmonics
All frequencies not
covered in above cells
Conducted
Power
Comment
+30 dBm
Maximum
6 dBi antenna
gain
-41.2 dBm
-20 dBc
Table 7.1 Summarized FCC 15.247 Regulations for the 2.4 GHz Band
7.1
Duty Cycling when Complying with FCC
For frequencies above 1 GHz, the field strength limits are based on average limits. When
using an averaging detector, a minimum bandwidth of 1 MHz shall be employed and the
measurement time shall not exceed 100 ms.
Due to the averaging detector, pulsed transmissions are allowed higher peak fundamental,
harmonic, and spurious power. This is a benefit for duty-cycled transmissions. The relaxation
factor is 20 log (TX on-time/100 ms) [dB]. A 50 % duty cycle will therefore allow for 6 dB
higher peak emission than without duty cycling. Notice however that, even when an
averaging detector is called for, there is still a limit on emissions measured using a peak
detector function with a limit 20 dB above the average limit.
7.2
Compliance of FCC Part 15.247 when using the CC2530 with the CC2591
When using CC2530 with the CC2591, duty cycling or back-off is only needed for highest
IEEE 802.15.4 channel (channel 26) to comply with FCC at maximum recommended output
power (TXPOWER = 0xE5). Table 7.2 below shows the duty cycling or back-off needed to
comply with the FCC Part 15.247 limits at typical conditions (TC = 25°C, VDD = 3.0 V,
TXPOWER = 0xE5). ZigBee and IEEE 802.15.4 systems are however typically low duty cycle
systems. Note that the numbers in Table 7.2 are based on conducted emission
measurements from the CC2530 - CC2591EM reference design [11]. The real required duty
cycling or back-off may be different for applications with different antennas, plastic covers, or
other factors that amplify/ attenuate the radiated power.
Figure 7.1 below shows the level of the conducted spurious emission and margins to the FCC
Part 15.247 limits for the IEEE 802.15.4 channels under typical conditions (TC = 25°C, VDD =
3.0 V) when transmitting at maximum recommended power (TXPOWER = 0xE5) using the
CC2530 - CC2591EM [11]. Figure 7.2 and Figure 7.3 show the margins versus the FCC
15.247 for the lowest frequency channels at the lower band edge and for the upper frequency
channels at the upper band edge respectively. At the band edge the FCC allows for a Markerdelta method measurement [10] to determine the amount of back off or duty cycle needed to
comply with the FCC Part 15.247. With Marker-delta method the field strength of the in-band
fundamental frequency is subtracted from the difference between the highest fundamental
emission level measured with a lower reference bandwidth and the emission level at the band
edge, as shown in Figure 7.3.
Page 14 of 19
SWRA308A
Application Note AN086
Frequency [MHz]
2405
2410
2415
2420
2425
2430
2435
2440
2445
2450
2455
2460
2465
2470
2475
2480
Back-Off [dB]
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
9.3
Duty Cycle
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
34%
Table 7.2 Duty-Cycle or Back-Off Requirement for FCC Part 15.247 Compliance under
Typical Conditions
Spurious emissions (FCC, RBW=1MHz, VBW=10Hz)
40
Conducted Spectral Power (dBm)
30
20
10
Channel 11
0
Channel 12
-10
Channel 18
-20
Channel 25
-30
Channel 26
FCC limit
-40
-50
-60
-70
2200
2250
2300
2350
2400
2450
2500
2550
2600
2650
2700
Frequency (MHz)
Figure 7.1 Conducted Spurious Emission vs. FCC Part 15.247 Limit
(TXPOWER = 0xE5, RBW = 1 MHz, VBW = 10 Hz)
Page 15 of 19
SWRA308A
Application Note AN086
Spurious emissions (FCC, RBW=1MHz, VBW=10Hz)
Conducted Spectral Power (dBm)
40
30
20
10
0
Channel 11
-10
Channel 12
FCC limit
-20
-30
-40
-50
-60
2385
2390
2395
2400
2405
2410
2415
2420
2425
Frequency (MHz)
Figure 7.2 Conducted Spurious Emission, Lower Band Edge
(TXPOWER = 0xE5, RBW = 1 MHz, VBW = 10 Hz)
Spurious emissions (FCC, RBW=1MHz, VBW=10Hz)
Conducted Spectral Power (dBm)
40
30
Channel 25
20
Channel 26
10
Channel 26 (RBW 100kHz)
FCC limit
0
-10
-20
-30
-40
-50
-60
-70
2460
2465
2470
2475
2480
2485
2490
2495
2500
Frequency (MHz)
Figure 7.3 Conducted Spurious Emission, Upper Band Edge
(TXPOWER = 0xE5, RBW = 1 MHz (100 kHz), VBW = 10 Hz)
Page 16 of 19
SWRA308A
Application Note AN086
8
Controlling the CC2591
There are four digital control pins (PAEN, EN, HGM, and RXTX) on the CC2591 controls the
state the chip is in. Table 8.1 below shows the control logic when connecting the CC2591 to a
CC2530 device.
PAEN
0
0
0
1
1
EN
0
1
1
0
1
RXTX
NC
NC
NC
NC
NC
HGM
X
0
1
X
X
Mode of Operation
Power Down
RX LGM
RX HGM
TX
Not allowed
Table 8.1 Control Logic for Connecting the CC2591 to a CC2530 Device
The CC2530 – CC2591EM reference design from TI uses three of the CC2530 GPIO pins on
the CC2530 to control the CC2591. The I/O pins used is shown in Figure 8.1.
CC2530
CC2591
P1_1
P1_4
PA_EN
EN
P0_7
HGM
Figure 8.1 CC2530-CC2591 Interconnect
For details how to configure the software to use the control signal and how to change I/O pins
to control the CC2591, please see [5].
When using the configuration used in the CC2530 – CC2591EM reference design, the
registers listed in Table 8.2 need to be changed from the recommended CC2530 settings to
control the CC2591 and give optimum performance. The new recommended values are listed
in Table 8.2.
CC2530 REGISTER
AGCCTRL1
FSCAL12
RFC_OBS_CTRL0
RFC_OBS_CTRL1
TXPOWER
OBSSEL1
OBSSEL4
P0DIR
ADDRESS
0x61B2
0x61AE
0x61EB
0x61EC
0x6190
0x6244
0x6247
0xFD
RECCOMMENED VALUE
0x15
0x00
0x68
0x6A
See Table 4.6
0xFB
0xFC
0x80
Table 8.2 New Recommended Register Settings for the CC2530 - CC2591 combination
2
AGCCTRL1 and FSCAL1 do not need to be changed in order to control the CC2591, but
are listed for completeness as they need to be updated from their default value. For more
information see CC253x User Guide [4].
Page 17 of 19
SWRA308A
Application Note AN086
All the recommended register CC2530 settings when including the CC2591 are automatically
implemented in SmartRF Studio when checking the Range Extender box. SmartRF Studio is
available on the TI website www.ti.com.
Page 18 of 19
SWRA308A
Application Note AN086
9
References
[1]
CC2530 Datasheet (SWRS081a.pdf)
[2]
CC2531 Datasheet (http://www.ti.com/lit/gpn/cc2531)
[3]
CC253x User Guide (SWRU191.pdf)
[4]
CC2591 Datasheet (SWRS070a.pdf)
[5]
TIMAC and Z-Stack Modifications for using CC2591 RF Front End with CC2530
(swra290.pdf)
[6]
AN058 Antenna Selection Guide (SWRA161.pdf)
[7]
DN007 2.4 GHz Inverted F Antenna (SWRU120B.pdf)
[8]
IEEE std. 802.15.4 – 2006: Wireless Medium Access Control (MAC) and Physical Layer
(PHY) specification for Low Rate Wireless Personal Area Networks (LR-WPANs)
(http://standards.ieee.org/getieee802/download/802.15.4-2006)
[9]
AN032 SRD Regulations for License-free Transceiver Operation in the 2.4 GHz Band
(SWRA060.pdf)
[10]
DA 00-705
(http://www.fcc.gov/Bureaus/Engineering_Technology/Public_Notices/2000/da000705.doc
)
[11]
CC2530 – CC2591EM Reference Design (SWRC171.zip)
10 General Information
10.1 Document History
Revision
SWRA308
SWRA308a
Date
2009.12.09
2009.12.18
Description/Changes
Initial release.
Updated reference list with CC2530-CC2591 reference design
Page 19 of 19
SWRA308A
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products
Amplifiers
Data Converters
DLP® Products
DSP
Clocks and Timers
Interface
Logic
Power Mgmt
Microcontrollers
RFID
RF/IF and ZigBee® Solutions
amplifier.ti.com
dataconverter.ti.com
www.dlp.com
dsp.ti.com
www.ti.com/clocks
interface.ti.com
logic.ti.com
power.ti.com
microcontroller.ti.com
www.ti-rfid.com
www.ti.com/lprf
Applications
Audio
Automotive
Broadband
Digital Control
Medical
Military
Optical Networking
Security
Telephony
Video & Imaging
Wireless
www.ti.com/audio
www.ti.com/automotive
www.ti.com/broadband
www.ti.com/digitalcontrol
www.ti.com/medical
www.ti.com/military
www.ti.com/opticalnetwork
www.ti.com/security
www.ti.com/telephony
www.ti.com/video
www.ti.com/wireless
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2009, Texas Instruments Incorporated
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising