MAX7042 Evaluation Kit
Evaluates: MAX7042
General Description
The MAX7042 evaluation kit (EV kit) allows for a detailed
evaluation of the MAX7042 superheterodyne receiver.
It enables testing of the device’s RF performance and
requires no additional support circuitry. The RF input
circuit is designed to work with a 50I source imped-
ance RF signal generator and has an SMA connector for
convenient connection to test equipment. The EV kit can
also directly interface to the user’s embedded design for
easy data decoding.
The MAX7042 EV kit comes in two versions, a 315MHz
version and a 433.92MHz version. The passive com-
ponents are optimized for these frequencies. These
components can be changed to work at 308MHz and
418MHz. In addition, the 4kbps Manchester received
data rate can be adjusted from 0kbps to 33kbps by
changing two more components.
For easy implementation into the customer’s design, the
MAX7042 EV kit also features a proven PCB layout that
can be duplicated easily for quicker time to market. The
EV kit Gerber files are available upon request.
S
Proven PCB Layout
S
Proven Components Parts List
S
Multiple Test Points Provided On Board
S
Available in 315MHz or 433.92MHz Optimized
Features
Versions
S
308MHz and 418MHz Operation Possible by
Changing Components
S
Fully Assembled and Tested
S
Can Operate as a Stand-Alone Receiver with the
Addition of an Antenna
Ordering Information
PART
MAX7042EVKIT-315+
MAX7042EVKIT-433+
TYPE
EV Kit
EV Kit
+Denotes
lead(Pb)-free and RoHS compliant.
Component List
DESIGNATION QTY
C1, C20, C21
3
DESCRIPTION
0.01FF
Q10%,
50V X7R ceramic
capacitors (0603)
Murata GRM188R71H103K
0.1FF
Q10%,
16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K
15pF
Q5%,
50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H150J
Not installed, ceramic capacitors
(0603)
100pF
Q5%,
50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H101J
315MHz:
1.2pF
Q0.1pF,
50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H1R2B
433.92MHz:
Not installed, ceramic capacitor
(0603)
DESIGNATION QTY
C11, C18
2
DESCRIPTION
220pF
Q10%,
50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H221K
1500pF
Q10%,
50V X7R ceramic
capacitor (0603)
Murata GRM188R71H152K
0.047FF
Q10%
50V X7R ceramic
capacitors (0603)
Murata GRM188R71H473K
470pF
Q5%
50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H471JA01
Black miniature test points
3-pin headers
Not installed, 3-pin headers
2-pin header
315MHz:
82nH
Q5%
inductor (0603)
Coilcraft 0603CS-82NXJLU
433.92MHz:
39nH
Q
5% inductor (0603)
Coilcraft 0603CS-39NXJLU
C2, C22
2
C12
1
C3, C4
C5, C6, C13,
C19
C7, C8, C9
2
C14, C15,
C16
3
0
C17
GND, TP8
JU1, JU4–JU11
JU2, JU3
JU12
1
2
9
0
1
3
C10
1
L1
1
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4963; Rev 0; 9/09
MAX7042 Evaluation Kit
Evaluates: MAX7042
Component List (continued)
DESIGNATION QTY
DESCRIPTION
315MHz:
3.9nH
Q5%
inductor (0603)
Coilcraft 0603CS-3N9XJLU
433.92MHz:
0I
Q5%
resistor (0603)
315MHz:
30nH
Q5%
inductor (0603)
Murata LQW18AN30NJ00
433.92MHz:
16nH
Q5%
inductor (0603)
Murata LQW18AN16NJ00
Not installed, resistors (0603)
100kI
Q5%
resistors
Not installed, SMA female vertical-
mount connectors
SMA female vertical-mount connector
Y2
—
—
1
9
1
DESIGNATION QTY
TP1–TP7, VDD
U1
8
1
DESCRIPTION
Red miniature test points
Low-power, FSK superheterodyne
receiver (32 TQFN-EP*)
Maxim MAX7042ATJ+
315MHz:
9.509375MHz crystal
Crystek 017034
433.92MHz:
13.2256MHz crystal
Crystek 017035
10.7MHz ceramic filter
TOKO #SK107M1N-AO-10
Shunts
PCB: MAX7042 EVALUATION KIT+
L2
1
Y1
1
L3
1
R1, R5
R2, R3, R4
REF_IN,
MIXOUT
RF_IN
0
3
0
1
*EP
= Exposed pad.
Component Suppliers
SUPPLIER
Coilcraft, Inc.
Crystek Corporation
Murata Electronics North America, Inc.
TOKO America, Inc.
PHONE
847-639-6400
800-237-3061
770-436-1300
847-297-0070
www.crystek.com
www.murata-northamerica.com
www.tokoam.com
WEBSITE
www.coilcraft.com
Note:
Indicate that you are using the MAX7042 when contacting these component suppliers.
Quick Start
•
•
•
MAX7042 EV kit
1)
2)
Required Equipment
Verify that the jumpers are in their default position,
as shown in Table 1.
Connect a DC supply set to 3.3V (through an amme-
ter, if desired) to the VDD and GND terminals on the
EV kit. Do not turn on the power supply.
Connect the RF signal generator to the RF_IN SMA
connector. Do not turn on the generator output.
Set the generator for an output carrier frequency
of 315MHz (or 433.92MHz) at a power level of
-100dBm. Set the modulation of the generator to
provide a FSK signal with ±50kHz frequency devia-
tion modulated with a 4kHz square wave.
Connect the oscilloscope to test point TP6 (DS+ or
data slicer positive input). Set the oscilloscope to
AC-coupling and set the vertical scale to approxi-
mately 100mV/div.
Regulated power supply capable of providing 3.3V
RF signal generator capable of delivering -120dBm
to 0dBm output power at the operating frequency, in
addition to frequency modulation (FM) capabilities
(Agilent E4420B or equivalent)
Optional ammeter for measuring supply current
Oscilloscope
3)
•
•
The MAX7042 EV kit is fully assembled and test-
ed. Follow the steps below to verify board operation.
Caution: Do not turn on the DC power supply or RF
signal generator until all connections are completed.
2
Procedure
4)
Maxim Integrated
MAX7042 Evaluation Kit
Evaluates: MAX7042
5)
Turn on the DC supply. The supply current should
read approximately 7.2mA for an EV kit that is set for
maximum sensitivity (JU4 pins 1-2 connected). To
draw slightly less current, with slightly less sensitiv-
ity, connect JU4 pins 2-3.
Remove the shunt from JU7 momentarily and restore
it to the 1-2 position. JU7 is the enable input and
toggling it once ensures that the FSK demodulator
is calibrated and operational.
Activate the RF generator’s output with modulation
and observe TP6 on the scope. Use the RF gen-
erator’s LF OUTPUT (modulation output) to trigger
the oscilloscope. The scope should show a 200mV
to 250mV peak-to-peak, lowpass-filtered square
wave. If the RF power is turned off, the scope trace
shows a noise voltage with high-amplitude and
high-frequency characteristics. These are the clicks
that characterize the response of an FM demodula-
tor to noise. To estimate the sensitivity, reduce the
RF power to a level where the square wave on the
scope is noisy but recognizable. This power level
should be below -107dBm. In some cases, the sen-
sitivity can be improved by removing the ammeter.
8)
Move the scope probe to TP3 (DATA), change the
coupling on the scope back to DC, and set the verti-
cal scale to 1V/div or 2V/div. A 4kHz square wave
going from ground to VDD (3.3V in this case) should
be seen. As the RF power is increased, this square
wave becomes cleaner. Another way to estimate
sensitivity from this test point is to reduce the RF
power until the square wave becomes extremely
asymmetric (duty cycle not 50%) and contains short-
data transitions (glitches) in the middle of a data
interval. This power level should be below -107dBm,
similar to the level seen in the previous step.
6)
7)
Layout Issues
A properly designed PCB is essential for any RF/micro-
wave circuit. Keep high-frequency input and output lines
as short as possible to minimize losses and radiation. At
high frequencies, trace lengths that are on the order of
λ/10
or longer can act as antennas.
Table 1. Jumper Table
JUMPER
JU1
JU2
JU3
JU4
SHUNT
POSITION
1-2*
2-3
—
—
1-2*
2-3
1-2
JU5
2-3
DESCRIPTION
Connects AVDD to VDD3
Connects AVDD to TP1
Not populated, leave open
Not populated, leave open
Selects high sensitivity
Selects normal sensitivity
Connects FSEL2 to VDD
(default for 433.92MHz); see
Table 2.
Connects FSEL2 to GND
(default for 315MHz); see
Table 2.
Connects FSEL1 to VDD; see
Table 2
Connects FSEL1 to GND; see
Table 2
JUMPER
JU7
JU8
JU9
SHUNT
POSITION
1-2*
2-3
1-2*
2-3
1-2*
2-3
1-2*
JU10
2-3
1-2
JU11
2-3
Open*
JU12
*Default
position.
1-2*
Open
DESCRIPTION
Turns on the MAX7042
Puts the MAX7042 in shutdown
Connects HVIN to VDD
Connects HVIN to TP4
Connects DVDD to VDD3
Connects DVDD to TP5
No peak-detector operation
Use peak detector for faster
receiver startup
Mixer output to MIXOUT
External IF input
Normal operation, leave open
Connects VDD to +3.3V supply
Connects VDD to +5V supply
1-2*
JU6
2-3
Maxim Integrated
3
MAX7042 Evaluation Kit
Evaluates: MAX7042
Both parasitic inductance and capacitance are influ-
ential on circuit layouts and are best avoided by using
short trace lengths. Generally, a 10-mil wide PCB trace,
0.0625in above a ground plane, with FR4 dielectric has
approximately 19nH/in of inductance and approximately
1pF/in of capacitance. In the LNA output/mixer input tank
circuit, the proximity to the MAX7042 IC has a strong
influence on the effective component values.
To reduce the parasitic inductance, use a solid ground
or power plane below the signal traces. Also, use low-
inductance connections to ground on all GND pins, and
place decoupling capacitors close to all VDD connec-
tions.
The MAX7042 EV kit PCB can serve as a reference
design for laying out a board using the MAX7042.
There is a MIXOUT location on the board that can be
populated with a board-mounted SMA connector to
monitor the IF output or to inject an IF signal into the
IFIN+ pin. Remove the ceramic filter (Y2) for such a
measurement and include R1 (270I) and C13 (0.01µF)
to match the 330I mixer output with the 50I spectrum
analyzer. Connect pins 1-2 of jumper JU11 to see the IF
output on the spectrum analyzer. Connect pins 2-3 of
jumper JU11 to inject an IF signal into the IFIN+ pin from
an external source.
For applications where the correct frequency crystal is
not available, it is possible to directly inject an external
frequency through the REF_IN SMA connector. Connect
the SMA to a function generator. The addition of C5 and
C6 (use 0.01µF capacitors), plus the removal of C3 and
C4 are necessary. The recommended amplitude of the
function generator is 500mV
P-P
.
Additional test points and I/O connectors are provided
to monitor the various baseband signals and for external
connections. See Tables 3 and 4 for a description.
REF_IN External Frequency Input
Detailed Description of Hardware
The MAX7042 can operate from 3.3V or 5V supplies. For
5V operation, remove jumper JU12 before connecting
the supply to VDD. AVDD is the output of an internal
regulator when VDD = 5V. AVDD and DVDD are con-
nected on the EV kit through VDD3. For 3.3V operation,
connect JU12.
The 10.7MHz IF can be monitored with an oscilloscope
or a spectrum analyzer. To monitor the IF output with an
oscilloscope, connect the scope probe to pin 3 of JU11.
Increase the RF signal generator power to approximately
-70dBm and set the scope amplitude to 20mV or 50mV
per division. Set the time per division on the horizontal
trace to 100ns. The scope trace shows the waveform at
the output of the external ceramic IF filter.
To monitor the IF output on a spectrum analyzer, use the
high-impedance probe attachment from the spectrum
analyzer, if one is available, and connect it to pin 3 of
JU11.
Power Supply
Test Points and I/O Connections
Table 3. Test Points
TEST POINT
1
2
3
4
5
6
7
DESCRIPTION
AVDD
RSSI
FSK data out
HVIN
DVDD
Positive input to data slicer
Negative input to data slicer
IF Input/Output
Table 4. I/O Connectors
TEST POINT
RF_IN
REF_IN
MIXOUT
GND
VDD
DESCRIPTION
RF input
External reference frequency input
IF input/output
Ground
Supply input
Table 2. Frequency Selection Table
FSEL2 (JU5)
0
0
1
1
FSEL1 (JU6)
0
1
0
1
FREQUENCY (MHz)
308
315
418
433.92
Note:
1 = 1-2 position; 0 = 2-3 position.
4
Maxim Integrated
MAX7042 Evaluation Kit
Evaluates: MAX7042
Figure 1. MAX7042 EV Kit Schematic
Maxim Integrated
5
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