19-3704; Rev 1; 3/07
308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver
General Description
The MAX7042 fully integrated, low-power, CMOS
superheterodyne RF receiver is designed to receive
frequency-shift-keyed (FSK) data at rates up to 66kbps
nonreturn-to-zero (NRZ) (33kbps Manchester). The
MAX7042 requires only a few external components to
realize a complete wireless RF receiver at 308, 315,
418, and 433.92MHz.
The MAX7042 includes all the active components
required in a superheterodyne receiver including a low-
noise amplifier (LNA), an image-rejection (IR) mixer, a
fully integrated phase-locked loop (PLL), local oscillator
(LO), 10.7MHz IF limiting amplifier with received-signal-
strength indicator (RSSI), low-noise FM demodulator,
and a 3V regulator. Differential peak-detecting data
demodulators are included for baseband data recovery.
The MAX7042 is available in a 32-pin thin QFN and
is specified over the automotive -40°C to +125°C
temperature range.
Features
♦
+2.4V to +3.6V or +4.5V to +5.5V Single-Supply
Operation
♦
Four User-Selectable Carrier Frequencies
308, 315, 418, and 433.92MHz
♦
-110dBm RF Input Sensitivity at 315MHz
♦
-109dBm RF Input Sensitivity at 433.92MHz
♦
Fast Startup (< 250µs)
♦
Small 32-Pin Thin QFN Package
♦
Low Operating Supply Current
6.2mA Continuous
20nA Power-Down
♦
Integrated PLL, VCO, and Loop Filter
♦
45dB Integrated Image Rejection
♦
Selectable IF BW with External Filter
♦
Positive and Negative Peak Detectors
♦
RSSI Output
MAX7042
Ordering Information
PART
MAX7042ATJ+
MAX7042AAX+**
TEMP RANGE PIN-PACKAGE
-40°C TO
+125°C
-40°C TO
+125°C
32 Thin QFN-EP*
36 SSOP
PKG
CODE
T3255-3
A36-2
Applications
Remote Keyless Entry
Tire-Pressure Monitoring
Home and Office Lighting Control
Remote Sensing
Smoke Alarms
Home Automation
Local Telemetry Systems
Security Systems
+Denotes
a lead-free package.
*EP
= Exposed paddle.
**Future
product—contact factory for availability.
Pin Configuration
PDMAX
DGND
DV
DD
OP+
DS+
TOP VIEW
24
N.C.
EN
FSEL1
FSEL2
HV
IN
DATA
LNASEL
N.C.
23
22
21
20
19
DS-
DF
18
17
16
15
14
13
IFIN+
IFIN-
AGND
MIXOUT
MIXIN-
MIXIN+
LNAOUT
LNASRC
25
26
27
28
29
30
31
32
+
1
N.C.
MAX7042
PDMIN
12
11
10
9
2
N.C.
3
N.C.
4
RSSI
5
XTAL2
6
XTAL1
7
AV
DD
8
LNAIN
Typical Application Circuit appears at end of data sheet.
THIN QFN
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver
MAX7042
ABSOLUTE MAXIMUM RATINGS
HVIN to AGND or DGND .......................................-0.3V to +6.0V
AVDD, DVDD to AGND or DGND..........................-0.3V to +4.0V
FSEL1, FSEL2, LNASEL,
EN, DATA...............................(DGND - 0.3V) to (HVIN + 0.3V)
All Other Pins............................(AGND - 0.3V) to (AVDD + 0.3V)
Continuous Power Dissipation (TA = +70°C)
32-Pin Thin QFN (derate 34.5mW/°C above +70°C)....2759mW
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Maximum RF Input Power ................................................+0dBm
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(Typical
Application Circuit,
50Ω system impedance, AV
DD
= DV
DD
= HV
IN
= +2.4V to +3.6V, f
RF
= 308, 315, 418, and 433.92MHz;
T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at AV
DD
= DV
DD
= HV
IN
= +3.0V, f
RF
= 433.92MHz,
P
RFIN
≤
-80dBm, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Supply Voltage (3V)
SYMBOL
V
DD
CONDITIONS
HV
IN
, AV
DD
, and DV
DD
connected
to power supply
HV
IN
connected to power supply,
AV
DD
and DV
DD
unconnected from
HV
IN
, but connected together
315MHz (3V)
315MHz (5V)
Supply Current
I
DD
434MHz (3V)
434MHz (5V)
All digital
inputs low
Operating, 1x I
LNA
Operating, 2x I
LNA
Operating, 1x I
LNA
Operating, 2x I
LNA
Operating, 1x I
LNA
Operating, 2x I
LNA
Operating, 1x I
LNA
Operating, 2x I
LNA
T
A
= +25°C
T
A
= +85°C
T
A
= +125°C
Shutdown Current (5V)
I
SHDN
All digital
inputs low
T
A
= +25°C
T
A
= +85°C
T
A
= +125°C
Time from EN = high to final signal
detection; does not include
baseband filter or data-
slicer reference settling
MIN
2.4
TYP
3.0
MAX
3.6
UNITS
V
Supply Voltage (5V)
HV
IN
4.5
5.0
6.2
6.8
6.4
7.0
6.4
7.0
6.6
7.2
0.02
0.1
0.85
0.6
1.4
4
5.5
V
8.7
8.6
8.4
9.2
mA
Shutdown Current (3V)
I
SHDN
µA
6
µA
7
Startup Time
t
ON
250
µs
DIGITAL I/O
Input High Threshold
Input Low Threshold
V
IH
V
IL
0.9 x HV
IN
0.1 x HV
IN
V
V
2
_______________________________________________________________________________________
308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver
DC ELECTRICAL CHARACTERISTICS (continued)
(Typical
Application Circuit,
50Ω system impedance, AV
DD
= DV
DD
= HV
IN
= +2.4V to +3.6V, f
RF
= 308, 315, 418, and 433.92MHz;
T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at AV
DD
= DV
DD
= HV
IN
= +3.0V, f
RF
= 433.92MHz,
P
RFIN
≤
-80dBm, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Input High Pulldown Current
Input Low-Leakage Current
Output High Voltage
Output Low Voltage
VOLTAGE REGULATOR
Output Voltage
V
REG
2.5
3.0
3.5
V
SYMBOL
I
IH
I
IL
V
OH
V
OL
CONDITIONS
HV
IN
= +3.6V
HV
IN
= +5.5V
HV
IN
= +3.6V
HV
IN
= +5.5V
I
SOURCE
= 500µA
I
SINK
= 500µA
MIN
TYP
8
20
<1
<1
HV
IN
- 0.4
0.4
MAX
15
40
1
1
UNITS
µA
µA
V
V
MAX7042
AC ELECTRICAL CHARACTERISTICS
(Typical
Application Circuit,
50Ω system impedance, AV
DD
= DV
DD
= HV
IN
= +2.4V to +3.6V, f
RF
= 308, 315, 418, and 433.92MHz;
T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at AV
DD
= DV
DD
= HV
IN
= +3.0V, f
RF
= 433.92MHz,
P
RFIN
≤
-80dBm, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Maximum Input Level
315MHz
setting
Sensitivity (Note 1)
434MHz
setting
Receiver Image Rejection
LNA/MIXER
Input Impedance (Note 2)
1dB Input Compression Point
(Notes 2, 3)
Input-Referred 3rd-Order Intercept
Point (Notes 2, 3)
LO Signal Feedthrough to
Antenna
Mixer Output Impedance
Zout
MIX
1x I
LNA
315MHz
Voltage Conversion Gain
330Ω IF filter
load
(Notes 2, 3)
2x I
LNA
315MHz
1x I
LNA
433.92MHz
2x I
LNA
433.92MHz
IF LIMITING AMPLIFIER
Input Impedance
-3dB Bandwidth
Z
11
330
10
Ω
MHz
Z
11
P
1dB
IIP3
Normalized to 2x I
LNA
315MHz
50Ω
2x I
LNA
433.92MHz
1x I
LNA
315MHz
2x I
LNA
315MHz
1x I
LNA
315MHz
2x I
LNA
315MHz
0.94 - j3.2
0.94 - j2.1
-47
-52
-37
-42
-80
330
52
57
47
52
dB
dBm
dBm
dBm
Ω
Operating, 1x I
LNA
Operating, 2x I
LNA
Operating, 1x I
LNA
Operating, 2x I
LNA
SYMBOL
CONDITIONS
MIN
TYP
0
-107
-110
-106
-109
45
dB
dBm
MAX
UNITS
dBm
_______________________________________________________________________________________
3
308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver
MAX7042
AC ELECTRICAL CHARACTERISTICS (continued)
(Typical
Application Circuit,
50Ω system impedance, AV
DD
= DV
DD
= HV
IN
= +2.4V to +3.6V, f
RF
= 308, 315, 418, and 433.92MHz;
T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at AV
DD
= DV
DD
= HV
IN
= +3.0V, f
RF
= 433.92MHz,
P
RFIN
≤
-80dBm, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Operating Frequency
RSSI Slope
FSK DEMODULATOR
Conversion Gain
ANALOG BASEBAND
Maximum Peak-Detector Bandwidth
Maximum Data-Filter Bandwidth
Maximum Data-Slicer Bandwidth
Maximum Data Rate
CRYSTAL OSCILLATOR
Crystal Frequency
Crystal Load Capacitance
f
XTAL
(f
RF
- 10.7)
/ 32
4.5
MHz
pF
BW
DF
BW
DS
Manchester coded
NRZ
50
50
100
33
66
kHz
kHz
kHz
kHz
1.1
2.1
3.0
mV/kHz
SYMBOL
f
IF
10
CONDITIONS
MIN
TYP
10.7
16
21
MAX
UNITS
MHz
mV/dB
Note 1:
0.2% BER, 4kbps, Manchester coded, 280kHz IF BW, ±50kHz frequency deviation.
Note 2:
Input impedance is measured at the LNAIN pin 2x I
LNA
. Note that the impedance at 315MHz includes the 3.9nH inductive
degeneration from the LNA source to ground. The impedance at 433.92MHz includes a 0nH inductive degeneration con-
nected from the LNA source to ground. The equivalent input circuit is 47Ω in series with 3.2pF at 315MHz and 47Ω in series
with 3.5pF at 433.92MHz.
Note 3:
The voltage conversion gain is measured with the LNA input matching inductor, the degeneration inductor, and the
LNA/mixer resonator in place, and does not include the IF filter insertion loss.
Typical Operating Characteristics
(Typical
Application Circuit,
V
DD
= 3.0V, f
RF
= 433.92MHz, IF BW = 280kHz, data rate = 4kbps Manchester encoded, frequency
deviation = ±50kHz, BER = 0.2%, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(1x I
LNA
)
MAX7042 toc01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(2x I
LNA
)
MAX7042 toc02
SUPPLY CURRENT vs. RF FREQUENCY
(1x I
LNA
)
MAX7042 toc03
7.2
7.0
SUPPLY CURRENT (mA)
6.8
6.6
6.4
6.2
6.0
5.8
5.6
5.4
2.4
2.7
3.0
3.3
-40°C
+25°C
+85°C
+125°C
8.0
7.8
7.6
SUPPLY CURRENT (mA)
7.4
7.2
7.0
6.8
6.6
6.4
6.2
6.0
-40°C
2.4
2.7
3.0
3.3
+25°C
+85°C
+125°C
7.0
6.8
SUPPLY CURRENT (mA)
6.6
6.4
6.2
6.0
5.8
5.6
-40°C
+125°C
+85°C
+25°C
3.6
3.6
300
325
350
375
400
425
450
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
RF FREQUENCY (MHz)
4
_______________________________________________________________________________________
308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver
MAX7042
Typical Operating Characteristics (continued)
(Typical
Application Circuit,
V
DD
= 3.0V, f
RF
= 433.92MHz, IF BW = 280kHz, data rate = 4kbps Manchester encoded, frequency
deviation = ±50kHz, BER = 0.2%, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. RF FREQUENCY
(2x I
LNA
)
+125°C
+85°C
+25°C
MAX7042 toc04
DEEP-SLEEP CURRENT vs. TEMPERATURE
MAX7042 toc05
BIT-ERROR RATE vs. AVERAGE INPUT POWER
(1x I
LNA
)
MAX7042 toc06
7.5
7.3
SUPPLY CURRENT (mA)
7.1
6.9
6.7
6.5
6.3
6.1
300
325
350
375
400
425
-40°C
1000
100
f
RF
= 433.92MHz
10
BIT-ERROR RATE
DEEP-SLEEP CURRENT (nA)
800
600
V
CC
= +3.6V
400
V
CC
= +3.0V
V
CC
= +2.4V
1
0.2% BER
0.1
f
RF
= 315MHz
0.01
200
0
450
-40
-15
10
35
60
85
110
RF FREQUENCY (MHz)
TEMPERATURE (°C)
-114
-112
-110
-108
-106
-104
AVERAGE INPUT POWER (dBm)
BIT-ERROR RATE vs. AVERAGE INPUT POWER
(2x I
LNA
)
MAX7042 toc07
SENSITIVITY vs. TEMPERATURE
(1x I
LNA
)
MAX7042 toc08
SENSITIVITY vs. TEMPERATURE
(2x I
LNA
)
MAX7042 toc09
100
f
RF
= 433.92MHz
10
-103
-104
SENSITIVITY (dBm)
-105
-106
f
RF
= 433.92MHz
-107
-108
-109
-106
-107
SENSITIVITY (dBm)
-108
-109
f
RF
= 433.92MHz
-110
-111
-112
BIT-ERROR RATE
1
0.2% BER
0.1
f
RF
= 315MHz
0.01
-117
-115
-113
-111
-109
-107
AVERAGE INPUT POWER (dBm)
f
RF
= 315MHz
-40
-15
10
35
60
85
110
f
RF
= 315MHz
-40
-15
10
35
60
85
110
TEMPERATURE (°C)
TEMPERATURE (°C)
SENSITIVITY
vs. FREQUENCY DEVIATION
FREQUENCY DEVIATION IS
MEASURED FROM 0 TO PEAK
MAX7042 toc10
RSSI AND DELTA
vs. IF INPUT POWER
1.8
1.5
1.2
RSSI (V)
0.9
0.6
DELTA
0.3
0
RSSI
MAX7042 toc11
FSK DEMODULATOR OUTPUT
vs. IF FREQUENCY
MAX7042 toc12
-100
-102
SENSITIVITY (dBm)
-104
-106
-108
-110
-112
1
3
FSK DEMODULATION OUTPUT (V)
2
1
DELTA (%)
0
-1
-2
-3
2.0
1.6
1.2
0.8
0.4
0
10.3
10.4
10.5
10.6
10.7
10.8
10.9
11.0
IF FREQUENCY (MHz)
10
FREQUENCY DEVIATION (kHz)
100
-90
-70
-50
-30
-10
10
RF INPUT POWER (dBm)
_______________________________________________________________________________________
5
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