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General Description
The MAX7044 crystal-referenced phase-locked-loop
(PLL) VHF/UHF transmitter is designed to transmit
OOK/ASK data in the 300MHz to 450MHz frequency
range. The MAX7044 supports data rates up to 100kbps,
and provides output power up to +13dBm into a 50
load while only drawing 7.7mA at 2.7V.
The crystal-based architecture of the MAX7044 elimi-
nates many of the common problems with SAW-based
transmitters by providing greater modulation depth,
faster frequency settling, higher tolerance of the trans-
mit frequency, and reduced temperature dependence.
The MAX7044 also features a low supply voltage of
+2.1V to +3.6V. These improvements enable better
overall receiver performance when using the MAX7044
together with a superheterodyne receiver such as the
MAX1470 or MAX1473.
A simple, single-input data interface and a buffered
clock-out signal at 1/16th the crystal frequency make
the MAX7044 compatible with almost any microcon-
troller or code-hopping generator.
The MAX7044 is available in an 8-pin SOT23 package
and is specified over the -40C to +125C automotive
temperature range.
Applications
Remote Keyless Entry (RKE)
Tire-Pressure Monitoring (TPM)
Security Systems
Garage Door Openers
RF Remote Controls
Wireless Game Consoles
Wireless Computer Peripherals
Wireless Sensors
Features
+2.1V to +3.6V Single-Supply Operation
OOK/ASK Transmit Data Format
Up to 100kbps Data Rate
+13dBm Output Power into 50 Load
Low 7.7mA (typ) Operating Supply Current*
Uses Small, Low-Cost Crystal
Small 3mm x 3mm 8-Pin SOT23 Package
Fast-On Oscillator: 250s Startup Time
* At 50% duty cycle (315MHz, 2.7V supply, +13dBm
output power)
MAX7044
300MHz to 450MHz High-Efficiency,
Crystal-Based +13dBm ASK Transmitter
________________________________________________________________
Maxim Integrated Products
1
DATA
CLKOUT
PAOUT
1
2
8
7
XTAL2
V
DD
GND
PAGND
XTAL1
SOT23
TOP VIEW
3
4
6
5
MAX7044
Pin Configuration
Ordering Information
MAX7044
1
XTAL1
ANTENNA
3.0V
3.0V
680pF
220pF
100nF
100nF
XTAL2
f
XTAL
8
2
GND
V
DD
7
3
PAGND
DATA INPUT
CLOCK
OUTPUT
(f
CLKOUT
=
f
XTAL
/16)
DATA
6
4
PAOUT CLKOUT
5
Typical Application Circuit
19-3221; Rev 0; 1/04
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.
EVALUATION KIT
AVAILABLE
PART
TEMP RANGE
PIN-
PACKAGE
TOP MARK
MAX7044AKA-T
-40C to +125C 8 SOT23-8
AEJW
MAX7044
300MHz to 450MHz High-Efficiency,
Crystal-Based +13dBm ASK Transmitter
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(Typical Application Circuit, all RF inputs and outputs are referenced to 50, V
DD
= +2.1V to +3.6V, T
A
= -40C to +125C, unless
otherwise noted. Typical values are at V
DD
= +2.7V, T
A
= +25C, unless otherwise noted.) (Note 1)
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.
V
DD
to GND ..........................................................-0.3V to +4.0V
All Other Pins to GND ................................-0.3V to (V
DD
+ 0.3V)
Continuous Power Dissipation (T
A
= +70C)
8-Pin SOT23 (derate 8.9mW/C above +70C)............714mW
Operating Temperature Range .........................-40C to +125C
Storage Temperature Range .............................-60C to +150C
Junction Temperature ......................................................+150C
Lead Temperature (soldering, 10s) .................................+300C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SYSTEM PERFORMANCE
Supply Voltage
V
DD
2.1
3.6
V
V
DATA
at 50% duty
cycle, (Notes 3, 4)
7.7
14.1
PA on (Note 5)
13.8
25.4
f
RF
= 315MHz
PA off (Note 6)
1.7
2.8
V
DATA
at 50% duty
cycle, (Notes 3, 4)
8.0
14.4
PA on (Note 5)
14.0
25.7
Supply Current
(Note 2)
I
DD
f
RF
= 433MHz
PA off (Note 6)
1.9
3.1
mA
T
A
< +25C
40
130
Standby Current
I
STDBY
V
DATA
< V
IL
for
more than WAIT
time (Notes 4, 7)
T
A
< +125C
550
2900
nA
Frequency Range (Note 4)
f
RF
300
450
MHz
Data Rate (Note 4)
0
100
kbps
Modulation Depth (Note 8)
ON to OFF P
OUT
ratio
90
dB
T
A
= +25
C, V
DD
=
+2.7V
9.6
12.5
15.4
T
A
= +125
C, V
DD
=
+2.1V
5.9
9.0
12.0
Output Power, PA On
(Notes 4, 5)
P
OUT
f
RF
= 300MHz to
450MHz
T
A
= -40
C, V
DD
=
+3.6V
13.1
15.8
18.5
dBm
Oscillator settled to within 50kHz
220
Turn-On Time (Note 8)
t
ON
Oscillator settled to within 5kHz
450
s
f
RF
= 315MHz
48
Transmit Efficiency with CW
(Notes 5, 10)
f
RF
= 433MHz
47
%
f
RF
= 315MHz
43
Transmit Efficiency with 50%
OOK (Notes 3, 10)
f
RF
= 433MHz
41
%
MAX7044
300MHz to 450MHz High-Efficiency,
Crystal-Based +13dBm ASK Transmitter
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(Typical Application Circuit, all RF inputs and outputs are referenced to 50, V
DD
= +2.1V to +3.6V, T
A
= -40C to +125C, unless
otherwise noted. Typical values are at V
DD
= +2.7V, T
A
= +25C, unless otherwise noted.) (Note 1)
Note 1: Supply current, output power, and efficiency are greatly dependent on board layout and PAOUT match.
Note 2: Production tested at T
A
= +25C with f
RF
= 300MHz and 450MHz. Guaranteed by design and characterization over tem-
perature and frequency.
Note 3: 50% duty cycle at 10kbps with Manchester coding.
Note 4: Guaranteed by design and characterization, not production tested.
Note 5: PA output is turned on in test mode by V
DATA
= V
CC
/2 + 100mV.
Note 6: PA output is turned off in test mode by V
DATA
= V
CC
/2 100mV.
Note 7: Wait time: t
WAIT
= (2
16
x 32) / f
RF
.
Note 8: Generally limited by PC board layout.
Note 9: V
DATA
= V
IL
to V
DATA
= V
IH
after V
DATA
= V
IL
for WAIT time: t
WAIT
= (216 x 32) / f
RF
.
Note 10: V
DATA
= V
IH
. Efficiency = P
OUT
/(V
DD
x I
DD
).
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PHASE-LOCKED LOOP (PLL)
VCO Gain
330
MHz/V
f
OFFSET
= 100kHz
-80
f
RF
= 315MHz
f
OFFSET
= 1MHz
-90
f
OFFSET
= 100kHz
-77
Phase Noise
f
RF
= 433MHz
f
OFFSET
= 1MHz
-87
dBc/Hz
f
RF
= 315MHz
-50
Maximum Carrier Harmonics
f
RF
= 433MHz
-50
dBc
f
RF
= 315MHz
-74
Reference Spur
f
RF
= 433MHz
-80
dBc
Loop Bandwidth
1.6
MHz
Crystal Frequency
f
XTAL
f
RF
/32
MHz
Frequency Pulling by V
DD
3
ppm/V
Maximum Crystal Inductance
50
H
Crystal Load Capacitance
3
pF
DATA INPUT
Data Input High
V
IH
V
DD
-
0.25
V
Data Input Low
V
IL
0.25
V
Maximum Input Current
10
A
Pulldown Current
10
A
CLKOUT OUTPUT
Output Voltage Low
V
OL
I
SINK
= 650A (Note 4)
0.25
V
Output Voltage High
V
OH
I
SOURCE
= 350A (Note 4)
V
DD
-
0.25
V
Load Capacitance
C
LOAD
(Note 4)
10
pF
CLKOUT Frequency
f
XTAL
/
16
Hz
MAX7044
300MHz to 450MHz High-Efficiency,
Crystal-Based +13dBm ASK Transmitter
4
_______________________________________________________________________________________
Typical Operating Characteristics
(Typical Application Circuit, V
DD
= +2.7V, T
A
= +25C, unless otherwise noted.) (Note 1)
7
9
11
13
15
17
19
21
23
2.1
2.4
2.7
3.0
3.3
3.6
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX7044 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
f
RF
= 315MHz
PA ON
T
A
= -40C
T
A
= +25C
T
A
= +85C
T
A
= +125C
5
6
7
8
9
10
11
12
13
2.1
2.4
2.7
3.0
3.3
3.6
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX7044 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +25C
f
RF
= 315MHz
PA 50% DUTY CYCLE AT 10kHz
T
A
= -40C
T
A
= +85C
T
A
= +125C
8
12
10
16
14
20
18
22
2.1
2.7
2.4
3.0
3.3
3.6
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX7044 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +25C
f
RF
= 433MHz
PA ON
T
A
= -40C
T
A
= +85C
T
A
= +125C
6
7
8
9
10
11
12
13
14
2.1
2.4
2.7
3.0
3.3
3.6
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX7044 toc04
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +25C
f
RF
= 433MHz
PA 50% DUTY CYCLE AT 10kHz
T
A
= -40C
T
A
= +85C
T
A
= +125C
8
10
14
12
16
18
2.1
2.7
2.4
3.0
3.3
3.6
OUTPUT POWER
vs. SUPPLY VOLTAGE
MAX7044 toc05
SUPPLY VOLTAGE (V)
OUTPUT POWER (dBm)
f
RF
= 315MHz
PA ON
T
A
= +25C
T
A
= -40C
T
A
= +85C
T
A
= +125C
8
10
14
12
16
18
2.1
2.7
2.4
3.0
3.3
3.6
OUTPUT POWER
vs. SUPPLY VOLTAGE
MAX7044 toc06
SUPPLY VOLTAGE (V)
OUTPUT POWER (dBm)
f
RF
= 433MHz
PA ON
T
A
= +25C
T
A
= -40C
T
A
= +85C
T
A
= +125C
-80
-78
-74
-76
-72
-70
2.1
2.7
2.4
3.0
3.3
3.6
REFERENCE SPUR MAGNITUDE
vs. SUPPLY VOLTAGE
MAX7044 toc07
SUPPLY VOLTAGE (V)
REFERENCE SPUR MAGNITUDE (dBc)
REFERENCE SPUR = f
RF
f
XTAL
f
RF
= 433MHz
f
RF
= 315MHz
-3
-1
-2
1
0
2
3
2.1
2.7
2.4
3.0
3.3
3.6
FREQUENCY STABILITY
vs. SUPPLY VOLTAGE
MAX7044 toc08
SUPPLY VOLTAGE (V)
FREQUENCY STABILITY (ppm)
f
RF
= 433MHz
f
RF
= 315MHz
30
35
40
45
50
55
60
65
70
2.1
2.4
2.7
3.0
3.3
3.6
TRANSMIT POWER EFFICIENCY
vs. SUPPLY VOLTAGE
MAX7044 toc09
SUPPLY VOLTAGE (V)
TRANSMIT POWER EFFICIENCY (%)
f
RF
= 315MHz
PA ON
T
A
= -40C
T
A
= +85C
T
A
= +125C
T
A
= +25C
MAX7044
300MHz to 450MHz High-Efficiency,
Crystal-Based +13dBm ASK Transmitter
_______________________________________________________________________________________
5
20
25
30
35
40
45
50
55
60
2.1
2.4
2.7
3.0
3.3
3.6
TRANSMIT POWER EFFICIENCY
vs. SUPPLY VOLTAGE
MAX7044 toc10
SUPPLY VOLTAGE (V)
TRANSMIT POWER EFFICIENCY (%)
f
RF
= 315MHz
PA 50% DUTY CYCLE AT 10kHz
T
A
= -40C
T
A
= +85C
T
A
= +125C
T
A
= +25C
30
35
40
45
50
55
60
65
70
2.1
2.4
2.7
3.0
3.3
3.6
TRANSMIT POWER EFFICIENCY
vs. SUPPLY VOLTAGE
MAX7044 toc11
SUPPLY VOLTAGE (V)
TRANSMIT POWER EFFICIENCY (%)
f
RF
= 433MHz
PA ON
T
A
= -40C
T
A
= +85C
T
A
= +125C
T
A
= +25C
15
25
20
40
35
30
55
50
45
60
2.1
2.7
2.4
3.0
3.3
3.6
TRANSMIT POWER EFFICIENCY
vs. SUPPLY VOLTAGE
MAX7044 toc12
SUPPLY VOLTAGE (V)
TRANSMIT POWER EFFICIENCY (%)
f
RF
= 433MHz
PA 50% DUTY CYCLE AT 10kHz
T
A
= +25C
T
A
= -40C
T
A
= +85C
T
A
= +125C
-140
-110
-120
-130
-100
-90
-80
-70
-60
-50
-40
0.01
1
0.1
10
100
1k
10k
PHASE NOISE vs. OFFSET FREQUENCY
MAX7044 toc13
OFFSET FREQUENCY (Hz)
PHASE NOISE (dBc/Hz)
2
4
6
8
10
12
14
16
18
0
1
10
100
1000
10,000
SUPPLY CURRENT AND OUTPUT POWER
vs. EXTERNAL RESISTOR
MAX7044 toc14
EXTERNAL RESISTOR ()
SUPPLY CURRENT (mA)
-16
-12
-8
-4
0
4
8
12
16
POWER
CURRENT
f
RF
= 315MHz
PA ON
OUTPUT POWER (dBm)
0
6
3
12
9
15
18
-10
-2
2
-6
6
10
14
SUPPLY CURRENT vs. OUTPUT POWER
MAX7044 toc15
OUTPUT POWER (dBm)
SUPPLY CURRENT (mA)
f
RF
= 315MHz
PA ON
50% DUTY CYCLE
50kHz/div
FREQUENCY SETTLING TIME
MAX7044 toc16
AM DEMODULATION OF PA OUTPUT
DATA RATE = 100kHz
MAX7044 toc17
OUTPUT SPECTRUM
MAX7044 toc18
Typical Operating Characteristics (continued)
(Typical Application Circuit, V
DD
= +2.7V, T
A
= +25C, unless otherwise noted.) (Note 1)
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