AN89878 WUSB-NX Hardware Design Guidelines.pdf

AN89878
WUSB-NX Hardware Design Guidelines
Author: Sai Prashanth Chinnapalli
Associated Project: N/A
Associated Part Family: CYRF9935
Software Version: N/A
Related Application Notes: For a complete list of the application notes, click here.
AN89878 provides the hardware design guidelines for Cypress WUSB-NX (WirelessUSB™ NX) transceiver. It provides
details to create schematics and PCB layouts for a WUSB-NX application. This note also includes a checklist that you
can use to confirm design and layout guidelines.
Contents
Introduction
Introduction .......................................................................1
Typical WUSB-NX Hardware Design ................................ 2
MCU Interface ..............................................................2
2.4 GHz Wireless Capability .........................................2
Comparison of Cypress’s WUSB-LP, WUSB-NL, WUSBNX .....................................................................................3
Schematic Design .............................................................3
WUSB-NX Pinout .........................................................3
Power Supply ...............................................................3
2.4 GHz RF Design ......................................................6
Layout Design ...................................................................7
PCB Layer Stackup ......................................................7
WUSB-NX Device Package Dimensions ......................7
Power Supply ...............................................................7
Clock ............................................................................8
2.4 GHz RF Design ......................................................8
Antenna Recommendations ....................................... 10
PIFA Antenna Dimensions ......................................... 11
Schematics and Layout Review Checklist ....................... 11
Reference Documents..................................................... 12
Worldwide Sales and Design Support ............................. 14
WUSB-NX is a device from Cypress WirelessUSB™
product family. It is a fourth-generation, ultra-low power,
2.4-GHz RF transceiver with a maximum data rate of
2 Mbps. WUSB-NX (CYRF9935) includes a fully
integrated receiver, transmitter, frequency synthesizer,
and baseband engine.
www.cypress.com
WUSB-NX applications include the following:






Wireless mice
Wireless touch mice
Wireless keyboards
Wireless trackpads
Wireless keyboards with trackpads
RF remote controls
A reference schematic and gerber format are provided
along with this application note to illustrate the design of a
WUSB-NX module with serial peripheral interface (SPI).
The reference schematic for a mouse design is also
provided with this application note. This application note
starts with the schematic design guidelines followed by
layout design guidelines. Finally, a design checklist helps
validate the PCB design.
Document No. 001-89878 Rev. **
1
WUSB-NX Hardware Design Guidelines
Typical WUSB-NX Hardware Design
A WUSB-NX hardware design typically consists of a MCU that can control the WUSB-NX radio using SPI. General interfaces
2
(Buttons, LEDs, I C, Programming, etc.) can be added to the MCU depending on the application.
Figure 1 illustrates a typical WUSB-NX based hardware design using a Cypress enCoRe MCU.
Figure 1. A Typical WUSB-NX Based Design (Wireless Mouse)
The following sections briefly describe the subsystems
that make up the design. The Schematic Design section
provides detailed schematics and layout guidelines.
For more information about the capabilities of WUSB-NX,
refer to the WUSB-NX datasheet listed in the Reference
Documents section.
MCU Interface
WUSB-NX radio to go into receive mode directly without
modifying the registers.
2.4 GHz Wireless Capability
WUSB-NX is a RF transceiver that can transmit and
receive in the 2.4 GHz ISM band. An antenna, along with
a matching network, needs to be connected to WUSB-NX
to implement wireless functionality.
WUSB-NX interfaces to an external MCU (CY7C69356,
CY8C42XX, CY7C604XX) over SPI. It acts as an SPI
slave, driven by the SPI master on the MCU. Other
WUSB-NX digital signals (like RST_n, Mode) can be
interfaced to the GPIOs of the MCU. The RST_n pin can
be used to reset WUSB-NX radio by driving the pin low
from the MCU. The Mode pin can be used to enable the
www.cypress.com
Document No. 001-89878 Rev. **
2
WUSB-NX Hardware Design Guidelines
Comparison of Cypress’s WUSB-LP,
WUSB-NL, WUSB-NX
Table 1 lists the differences between WUSB-LP
(CYRF6936), WUSB-NL (CYRF8935), and WUSB-NX
(CYRF9935). WUSB-LP and WUSB-NL are previous
generation radios from Cypress.
Table 1. WUSB-LP, WUSB-NL, WUSB-NX
Parameter
WUSB-LP
WUSB-NL
WUSB-NX
Radio
2.4 GHz
with GFSK
or DSSS
modulation
2.4 GHz with
GSFK
modulation
2.4 GHz
with GSFK
modulation
Radio Tx Power
+4 dBm
+1 dBm
+4 dBm
Tx Current
Consumption at
0 dBm
26.2 mA
18.5 mA
12 mA
Rx current
consumption
21.2 mA
18 mA
15 mA
Max Receive
Sensitivity
–97 dBm
–87 dBm
–93 dBm
(125 Kbps)
(1 Mbps)
(250 Kbps)
1 Mbps/
250 Kbps
125 Kbps
1 Mbps
2 Mbps/
250 Kbps
Power Supply
The power supply consists of a power source such as AA
or AAA batteries and an optional DC-DC regulator.
Power Supply Design
WUSB-NX can operate in the voltage range of 1.9 V to
3.6 V. Cypress recommends that you use an external DCDC regulator for the following types of applications:


Applications powered by a single AA or AAA battery
Applications with parts that require a constant supply
voltage, such as mouse optical sensors
Figure 3 shows a reference power supply design for
WUSB-NX using an external DC-DC regulator
SC120ULTRT. VREG of the regulator shall be connected
to the VIN of the WUSB-NX to power the radio.
Figure 3. Reference Power Supply Design Schematic
VREG
1
L2
4.7uH
SW4
2
VBAT
3
U3
LX
GND1
2
1
3
SPDT
BATTERY
BT1
BATTERY
BT2
IN
FB
EN
6
Low ESR
C15
5 22uF
C16
0.10uF
4
7
Data Rate
OUT
TPAD
SC120ULTRT
Low ESR
+
C17
22uF
Schematic Design
This section gives details about WUSB-NX support
circuitry.
DC-DC Regulator Part Selection Criteria
The DC-DC regulator part must meet the following criteria:
WUSB-NX Pinout


WUSB-NX is available in a 24-pin QFN (4×4 mm).
Figure 2 shows the pinout.
GND

1
18
VIN
RST_n
2
17
GND
Test1
3
16
GND
Test2
4
15
ANT2
VDD_LDO
5
14
ANT1
GND
6
13
VDD_PA
www.cypress.com
7
8
9
10
11
12
VIN
XIN
GND
GND
VIN
CYRF9935
XOUT
MIS O
The output noise of the regulator is less than 50 mV
pk-pk.
Reference DC-DC Regulator Parts
Two recommended regulators are shown in Table 2.
19
SPI_nSS
MODE
MOSI
22
20
SCK
23
21
IRQ
24
Figure 2. 24-Pin QFN WUSB-NX Pinout
The output voltage range is 1.9 V to 3.6 V.
SC120ULTRT: Semtech SC120ULTRT is a highefficiency, low-noise, synchronous step-up DC-DC
converter that provides boosted voltage levels in
handheld applications. The input voltage can vary from
0.7 V to 4.5 V to provide an output voltage of 3.3 V for
the system. This regulator can be used for single AA or
AAA battery applications.

LT1763CS8-3.3: The Linear Technology LT1763 is a
low-noise, low-dropout regulator (LDO) capable of
supplying 500 mA of output current with a dropout
voltage of 300 mV. The maximum current that the
WUSB-NX radio consumes is 12 mA during the transmit
stage. This regulator can drive much higher current than
required current. LT1763 parts are available in an 8-pin
package. Because these parts can support input voltages
of 3.7 V to 20 V, they can be used in designs where an
Document No. 001-89878 Rev. **
3
WUSB-NX Hardware Design Guidelines
AC-DC adapter or lithium-ion batteries are used as a
power source. This regulator cannot be used for single
AA or AAA battery applications.
Table 2: Reference DC-DC Regulator Parts
C r ys t a l R e q u i r e m e n t s
WUSB-NX requires an external crystal. Figure 5 shows
the reference schematic for the clock circuit.
Regulator Part
Number and Type
Manufacturer
VBAT
(V)
VREG
(V)
SC120ULTRT
Step-Up
0.7–3.8
3.3
(Semtech
Corporation)
DC-DC
Regulator
Recommended
for single AA or
AAA battery
applications like
wireless mouse
and keyboard
LT1763CS83.3
LDO
Regulator
3.7–20
3.3
Recommended
for 9-V battery
applications like
radio controlled
hobby vehicle
and toys
Remark
U2
(Linear
Technology)
P o w e r S u p p l y C o n n e c t i vi t y
Three VIN pins of the WUSB-NX are the power input
sources for the radio. VIN supports the operating voltage
that can vary from 1.9 V to 3.6 V. Each VIN pin should be
derived from the common supply and separately
decoupled. WUSB-NX has a built-in LDO providing a
constant output of 1.8 V (VDD_OUT), which powers the
internal blocks of the radio. This pin needs to be
decoupled with the capacitor (C4) and should not to be
used to power external circuitry. The capacitor is required
to reduce the power noise. VDD_PA pin provides power to
the antenna from the internal regulator of the device.
VREG of the DC-DC regulator is connected to VIN of the
WUSB-NX.
MISO
RST_N
Test1
Test2
VDD_LDO
GND
VIN
GND
GND
ANT2
ANT1
VDD_PA
18
17
16
15
14
13
7
8
9
10
11
12
VIN
XOUT
XIN
GND
GND
VIN
1
2
3
4
5
6
IRQ
SCK
MOSI
MODE
SPI_SS
GND
WUSB-NX
24
23
22
21
20
19
Figure 5. Clock Circuit Design
Rf
1M
Y1
C1
36pF
16MHz
C2
12pF
The crystal must meet the following criteria:


Fundamental mode, parallel resonant 16.000 MHz
Frequency tolerance of ±60 ppm. This tolerance must
be calculated by using the RSS (root square sum)
approach involving the following four types of errors
represented in parts per million:

Base, or initial
temperature (Ippm)
Figure 4 shows the connectivity among the VIN,
VDD_LDO, and VDD_PA pins.

Figure 4. WUSB-NX Power Supply Connectivity
Drift due to temperature changes within the
o
o
operating temperature range of 0 C to 70 C
(Tppm)


Drift attributed to aging (Appm)
U2
24
23
22
21
20
19
VIN
1
2
3
4
5
6
MISO
RST_N
Test1
Test2
VDD_LDO
GND
C1
22pF
VIN
GND
GND
ANT2
ANT1
VDD_PA
C2
2.2nF
18
17
16
15
14
13
measured
at
room
Uncertainty caused by load capacitance error
(Lppm)
Apply the following formula to calculate the total frequency
tolerance using the RSS approach:
Equation 1:
VIN
XOUT
XIN
GND
GND
VIN
1.8V
IRQ
SCK
MOSI
MODE
SPI_SS
GND
WUSB-NX
error,
7
8
9
10
11
12
C4
1uF
VIN
C6
22pF
L3
3.9nH
VIN
C7
1uF
www.cypress.com
C8
22pF
C9
C10
2.2nF 22pF

36-pF and 12-pF capacitances are preferred on each
of the nodes of crystal (C1 and C2 respectively in
Figure 5).
C11
2.2nF
Document No. 001-89878 Rev. **
4
WUSB-NX Hardware Design Guidelines
R e f e r e n c e C r ys t a l P a r t s
Table 3 shows a list of recommended crystals.
Figure 6. Crystal Circuit
Table 3. Recommended Crystals
MPN
Manufacturer
Stability
Load Cap.
AT-16.000MAGE-T
TXC Corp
30 ppm
12 pF
TSX-3225
16.0000MF09ZAC3
EPSON
10 ppm
12 pF
XIN
XOUT
Calculating Load Capacitance Values
Load capacitors play a critical role in providing an accurate
clock source to WUSB-NX, which determines RF signal
accuracy. These capacitors must be chosen carefully
based on the load capacitance value of the crystal. This
section explains the procedure to choose the correct load
capacitor values.
Figure 6 illustrates the crystal circuit. To provide the most
accurate clock source, crystal manufacturers specify the
optimum load capacitance for the circuit. The two
capacitors (C1 and C2) determine the load capacitance,
and the net load capacitance is calculated using the
following equation:
Equation2:
Cs is the stray capacitance of the PCB, whose typical
value is 2.5 pF. Hence, the values of C1 and C2 must be
chosen in such a way that they match the crystal’s
specification. For example, if 10 pF is the load capacitance
of the crystal, then the tuning capacitor value would be 15
pF for both C1 and C2. The stray capacitance of the board
is assumed to be 2.5 pF which is good assumption. In
general, the smaller the value of series resistor R1 (Figure
6), the faster the oscillator will start. R1 must be large
enough to avoid overdriving the crystal; yet small enough
to provide enough current to start oscillation quickly (an
R1 that’s too large could cause the oscillator to fail to
start). R1 can in some cases be zero (shorted), especially
with high-frequency crystals. Rf (Figure 6) is known as
feedback resistance, is used to bias the input of the
inverting amplifier. By pulling the input of the amplifier
toward the voltage at the output, an unstable condition is
created, stimulating oscillation. It can also be observed
that feedback resistance affects the loop gain of the
amplifier, which is augmented as the value for the
feedback resistance is increased. In general, lowerfrequency crystals require higher values for Rf because
their impedance is normally higher than that of highfrequency crystals. Rf for the WUSB-NX radio is 1 MΩ and
R1 is 0 Ω.
www.cypress.com
MCU and RF Connectivity
The external MCU interfaces with WUSB-NX over SPI.
When using the enCoRe V (CY7C60456) MCU, the
following connections are to be made:

Connect MOSI (Pin22) of WUSB-NX to Pin17 of
enCoRe V

Connect MISO (Pin1) of WUSB-NX to Pin13 of
enCoRe V

Connect SCK (Pin23) of WUSB-NX to Pin16 of
enCoRe V

SPI_SS can be connected to any GPIO (for example
Pin12)

Connect MODE to any GPIO pin. The WUSB-NX
Mode pin can be used in the firmware for a smart
receive mechanism.
Figure 7 shows the connectivity between the enCoRe V
MCU and WUSB-NX blocks. It’s a good idea to add test
points on the interface signal lines (SPI, Mode, IRQ,
RST_n) to help debugging during firmware development.
For other MCUs, refer to the respective MCU datasheet
for their SPI port I/Os.
Document No. 001-89878 Rev. **
5
WUSB-NX Hardware Design Guidelines
21
41
Figure 7. MCU and RF Connectivity
1
NC5
NC6
P2_0
P2_1
P2_2
P2_3
P2_4
P2_5
P2_6
P2_7
NC1
22
17
23
16
24
13
25
12
33
5
34
4
35
3
36
2
U2
SPI_MOSI
WUSB-NX
SPI_CLK
1
2
3
4
5
6
WUSB-NX_IRQ
24
23
22
21
20
19
P1_0
P1_1
P1_2
P1_3
P1_4
P1_5
P1_6
P1_7
RX_ENABLE
IRQ
SCK
MOSI
MODE
SPI_SS
GND
20
19
XRES
37
48
38
46
39
45
40
44
MISO
RST_N
Test1
Test2
VDD_LDO
GND
VIN
GND
GND
ANT2
ANT1
VDD_PA
18
17
16
15
14
13
VIN
XOUT
XIN
GND
GND
VIN
26
P0_0
P0_1
P0_2
P0_3
P0_4
P0_5
P0_6
P0_7
SPI_MISO
7
8
9
10
11
12
VDD1
VDD2
U4
RST_n
SPI_SS
NC0
NC2
NC3
NC4
CY 7C60456-48LTXC
P4_0
P4_1
P4_2
P4_3
27
11
28
10
29
9
30
8
31
7
32
6
18
47
VSS1
VSS2
43
42
14
15
P3_0
P3_1
P3_2
P3_3
P3_4
P3_5
P3_6
P3_7
2.4 GHz RF Design
Figure 8. WUSB-NX RF Design Overview
This section explains the radio interface to the antenna.
2 . 4 G H z R F D e s i g n O ve r vi e w
WUSB-NX is a RF transceiver that can provide up to
2 Mbps data throughput. It supports a differential RF
input/out using ANT1 and ANT2 pins. These pins must be
connected to a matching network to provide 50-
impedance matching for WUSB-NX and the antenna as
shown in Figure 8.
www.cypress.com
50 Ohm
Antenna
WUSB NX
Document No. 001-89878 Rev. **
MATCHING
NETWORK
6
WUSB-NX Hardware Design Guidelines
Impedance-Matching Circuit Design
Two capacitors and three inductors form the matching
network, which matches the impedances between
WUSB-NX and the antenna. The values shown in Table 4
must not be modified. When you select these components,
choose parts that have a low power loss. The chosen
parts should exhibit a minimum Q of approximately 20 or
better, at 2.4 GHz. Table 4 provides recommended part
numbers for the matching network.
Layout Design
Table 4. Matching Network Passives
Figure 10 illustrate the layer stackup for a two-layer design
Type
MPN
Manufacturer
Values
Inductor
(L1)
LQG18HN3N9S00D
Emerson
Network
3.9 nH
The following sections discuss the layout guidelines for
creating WUSB-NX based hardware designs.
PCB Layer Stackup
WUSB-NX based hardware can be designed on a twolayer PCB design. Follow these guidelines to attain
optimum RF performance.
Figure 10. Two-Layer Stackup
Silk Screen
Layer1(Sensors, Ground, Antenna)
Inductor
(L3)
LQG18HN3N9S00D
Emerson
Network
3.9 nH
Inductor
(L2)
LQG18HN5N6S00D
Murata
Electronics
5.6 nH
Resistor
(R10)
ERJ-3EKF2002V
Panasonic
Electronic
20 k
Capacitor
(C5)
CC0603CRNPO9BN
1R0
Yageo
1 pF
Capacitor
(C3)
C1608C0G1H050C0
80AA
TDK
Corporation
5 pF
PCB
Layer2(Components, Routing)
FR4-based PCB designs perform well with board
thicknesses ranging from 0.020 inches (0.5 mm) to
0.063 inches (1.6 mm).
WUSB-NX Device Package Dimensions
The 24-pin device is available in a QFN package. Table 5
lists the package size and recommended pad size:
Table 5. WUSB-NX Package Details
The differential antenna input/output (ANT2) pin should
have a resistance to ground of 51 Ω ± 20 percent to match
its 50 Ω impedance which is set by the matching network.
In addition, the ANT1 pin requires a DC path to ground. A
resistor of 20 kΩ ± 20 percent to ground must be placed
on the antenna-side end of the matching network, as
shown in Figure 9, if the selected antenna does not have a
return path to ground.
24 Pin QFN
Package Size
4 mm × 4 mm
Recommended
Pad Size
0.25 mm
Power Supply
Figure 9. Matching Network Design
MISO
RST_N
Test1
Test2
VDD_LDO
GND
VIN
GND
GND
ANT2
ANT1
VDD_PA
18
17
16
15
14
13
4
3
2
1
C3
L1
VIN
XOUT
XIN
GND
GND
VIN
1
2
3
4
5
6
IRQ
SCK
MOSI
MODE
SPI_SS
GND
WUSB-NX
24
23
22
21
20
19
Power Supply Design
U2
3.9nH
5pF
C5
7
8
9
10
11
12
L2
5.6nH
R10
20k

Place decoupling capacitors as close as possible to
WUSB-NX.

Do not gang the decoupling capacitors. Instead,
connect them individually to the corresponding power
terminals.
1pF
WIGGLE
ANT1
L3
3.9nH
C11
22pF
www.cypress.com
C15
2.2nF
Document No. 001-89878 Rev. **
7
WUSB-NX Hardware Design Guidelines
Figure 12. Antenna Matching Network
Clock

Do not route any trace beneath the crystal pads or
traces connecting the crystal and other components to
XIN and XOUT. The layer beneath the crystal pads
and these traces must have solid ground, as shown in
Figure 11.

Place the crystal as close as possible to WUSB-NX.
Figure 11. Crystal Layout Design
2.4 GHz RF Design

WUSB-NX supports different types of antenna
designs. Refer to the Antenna Recommendations
section for the list of antenna designs. This application
note also provides the PIFA Antenna Dimensions.
Select an antenna design that suits your application.
The guidelines provided in this document are based
on the PIFA antenna, but they also apply to other
antenna too.

Place the antenna matching network passives as
shown in Figure 12.

Use vias to implement ground stitching between the
top and bottom layers underneath the WUSB-NX
EPAD.
www.cypress.com

Maximize ground in the complete design. Ensure that
all grounds in the system are tied together.

Ensure that the layer beneath the WUSB-NX EPAD is
solid ground and that it is extended out to the antenna
feed line, as shown in Figure 13. Note that the ground
regions are colored in blue.

Ensure that the top layer on which WUSB-NX is
mounted has a solid ground pad that aligns with the
WUSB-NX EPAD and this pad is soldered to the
EPAD. In addition, connect the ground pad on the top
layer to the ground pad located on the layer beneath
using thermal vias.
Figure 13. Ground Below EPAD and Antenna Feed Line
Document No. 001-89878 Rev. **
8
WUSB-NX Hardware Design Guidelines

Do not route any I/Os near the ANT1 and ANT2
parallel to the ANT1 and ANT2 lines.


Connect all grounds on the hardware together.
Isolate the antenna from other layers, and do not add
any signal traces or ground to any of the layers
beneath the antenna, as shown in Figure 14.
Figure 14. Isolation of Antenna

During PCB manufacturing, do not place metal
content such as a PCB vendor logo, Pb-free symbol,
or manufacturing lot number under the antenna,
because any metal under the antenna can affect the
RF radio range. Ensure that this is mentioned
explicitly in the fabrication notes of layout design files.
www.cypress.com
Document No. 001-89878 Rev. **
9
WUSB-NX Hardware Design Guidelines
Antenna Recommendations
The antenna is usually the most important factor in achieving a successful RF performance. A rigorous antenna tutorial is
beyond the scope of this application note, but here are some simple antenna recommendations that you can apply to
WUSB-NX based applications.
You can use virtually any type of good-quality 50-, 2.4 GHz antenna with WUSB-NX. Table 6 lists several available choices.
Table 6. Antenna Choices
Antenna
Type
Picture or Drawing
Wiggle
antenna
Custom
printed-trace
antenna
This is a specialized antenna,
customized to each application.
Chip antenna
PCB
Size(mm)
Applications
used
Description/Notes
10 X 10 X 0.1
Wireless
keyboard,
Wireless mouse,
Wireless remote
controls, Wireless
dongles
Described in the Cypress application note
AN48610 – Design and Layout Guidelines for
Matching
Network
and
Antenna
for
WirelessUSB™ LP Family
Wireless
keyboard,
Wireless mouse,
Wireless remote
controls, Wireless
dongles
Cost: Almost free when added to the existing
PCB
Wearable devices,
sensor tags,
Wireless dongles
Easy to use.
Depends
the design
on
3.2 × 1.6 × 1.3
Model 2450AT18B100E,
Johanson Technology, Inc.
Cost: Almost free when added to the existing
PCB
Read the datasheet and follow all the
manufacturer instructions. The manufacturer’s
specifications for mounting and layout must be
exactly followed
Cost: Can be expensive
PIFA
22 × 7 × 0.1
1/2 wave
end-fed
dipole
Length : 109.3
Diameter:10
Wireless
keyboard,
Wireless mouse,
Wireless remote
controls
The printed inverted F-antenna (PIFA)
Radio controlled
hobby vehicle and
toys
Delivers “textbook” 0-dBm performance
Cost: Almost free when added to the existing
PCB
Offers easy removal and replacement
Accommodates EMC compliance and end
applications
Requires RF connect on the board
Cost: Relatively expensive
Illustrated:
Pulse.
www.cypress.com
Model W1010,
by
Document No. 001-89878 Rev. **
10
WUSB-NX Hardware Design Guidelines
PIFA Antenna Dimensions
Figure 15 shows the detailed dimensions of the PIFA antenna for use in WUSB-NX designs.
Figure 15. PIFA Antenna Dimensions
Schematics and Layout Review Checklist
Table 7 is a checklist for all the important guidelines. Provide an answer to each checklist item to find out the extent to which
your hardware design meets these guidelines. The answer “Yes” is considered as you are meeting the design requirement.
Table 7. Schematics and Layout Review Checklist
Answer
S.No
Checklist Item
1
Are all three VIN pins connected together to the same source?
2
Is connectivity between the MCU and WUSB-NX blocks established over SPI?
3
Are test points added on the SPI lines connecting the MCU and WUSB-NX blocks?
4
Does the power supply design ensure that battery leakage does not occur under a low battery condition?
5
Is the antenna laid out exactly according to the dimensions?
6
Is it ensured that there is no ground/trace running below the PIFA antenna?
7
Is adequate solid ground added below the ANT1, ANT2 pins and antenna feed line?
8
Are decoupling capacitors placed close to the power pins?
9
Is solid ground added below the crystal pads?
10
Are all the grounds connected together?
11
Are the mounting pads laid out according to spec (0.25 mm) for the 24-pin QFN package)?
www.cypress.com
(Yes/No)
Document No. 001-89878 Rev. **
11
WUSB-NX Hardware Design Guidelines
Answer
S.No
Checklist Item
12
Are the grounds on each layer interconnected using as many vias as possible?
13
Is the Vin Ripple less than 50 mV peak-to-peak?
14
Are there any signal metal deposits near the Antenna?
(Yes/No)
Reference Documents
For more information, refer to the following documentation available at www.cypress.com:






AN48610 – Design and Layout Guidelines for Matching Network and Antenna for WirelessUSB™ LP Family
AN4004 - Interference Mitigation Challenges and Solutions in the 2.4 to 2.5 GHz ISM Band
AN5033 - WirelessUSB Dual Antenna Design Layout Guidelines
AN64285- WirelessUSB NL Low Power Radio Recommended Usage and PCB Layout
WUSB-NX Datasheet
Impedance Matching
www.cypress.com
Document No. 001-89878 Rev. **
12
WUSB-NX Hardware Design Guidelines
Document History
Document Title: WUSB-NX Hardware Design Guidelines – AN89878
Document Number: 001-89878
Revision
ECN
Orig. of
Change
Submission
Date
**
4370191
CSAI
05/05/2014
www.cypress.com
Description of Change
New Application Note
Document No. 001-89878 Rev. **
13
WUSB-NX Hardware Design Guidelines
Worldwide Sales and Design Support
Cypress maintains a worldwide network of offices, solution centers, manufacturer’s representatives, and distributors. To find
the office closest to you, visit us at Cypress Locations.
PSoC® Solutions
Products
Automotive
cypress.com/go/automotive
psoc.cypress.com/solutions
Clocks & Buffers
cypress.com/go/clocks
PSoC 1 | PSoC 3 | PSoC 5LP
Interface
cypress.com/go/interface
Lighting & Power Control
cypress.com/go/powerpsoc
cypress.com/go/plc
Memory
cypress.com/go/memory
PSoC
cypress.com/go/psoc
Touch Sensing
cypress.com/go/touch
USB Controllers
cypress.com/go/usb
Wireless/RF
cypress.com/go/wireless
Cypress Developer Community
Community | Forums | Blogs | Video | Training
Technical Support
cypress.com/go/support
PSoC is a registered trademark and WirelessUSB is a trademark of Cypress Semiconductor Corp. All other trademarks or registered trademarks
referenced herein are the property of their respective owners.
Cypress Semiconductor
198 Champion Court
San Jose, CA 95134-1709
Phone
Fax
Website
: 408-943-2600
: 408-943-4730
: www.cypress.com
© Cypress Semiconductor Corporation, 2014. The information contained herein is subject to change without notice. Cypress Semiconductor
Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any
license under patent or other rights. Cypress products are not warranted nor intended to be used for medical, life support, life saving, critical control or
safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as
critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The
inclusion of Cypress products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies
Cypress against all charges.
This Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide
patent protection (United States and foreign), United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a
personal, non-exclusive, non-transferable license to copy, use, modify, create derivative works of, and compile the Cypress Source Code and derivative
works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in conjunction with a Cypress
integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source
Code except as specified above is prohibited without the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT
NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the
right to make changes without further notice to the materials described herein. Cypress does not assume any liability arising out of the application or
use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in life-support systems where a
malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems
application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
www.cypress.com
Document No. 001-89878 Rev. **
14