19-3221; Rev 4; 2/11
300MHz to 450MHz High-Efficiency,
Crystal-Based +13dBm ASK Transmitter
MAX704
General Description
Features
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 50Ω
load while only drawing 7.7mA at 2.7V.
o +2.1V to +3.6V Single-Supply Operation
o OOK/ASK Transmit Data Format
o Up to 100kbps Data Rate
o +13dBm Output Power into 50Ω Load
o Low 7.7mA (typ) Operating Supply Current*
o Uses Small, Low-Cost Crystal
o Small 3mm x 3mm 8-Pin SOT23 Package
o Fast-On Oscillator: 250μs Startup Time
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.
* At 50% duty cycle (315MHz, 2.7V supply, +13dBm output
power)
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 -40°C to +125°C automotive
temperature range.
Ordering Information
PIN-
PART
TEMP RANGE
TOP MARK
PACKAGE
MAX7044AKA+T -40°C to +125°C 8 SOT23
Applications
Remote Keyless Entry (RKE)
Tire-Pressure Monitoring (TPM)
Security Systems
AEJW
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Garage Door Openers
RF Remote Controls
Wireless Game Consoles
Wireless Computer Peripherals
Wireless Sensors
Typical Application Circuit
Pin Configuration
TOP VIEW
f
XTAL
3.0V
3.0V
1
2
8
7
XTAL2
XTAL1
GND
+
XTAL1
GND
1
2
3
4
8
7
6
5
XTAL2
220pF
100nF
680pF
100nF
V
DD
V
DD
MAX7044
MAX7044
3
4
6
5
DATA INPUT
PAGND
PAOUT
DATA
ANTENNA
DATA
PAGND
CLOCK
CLKOUT
OUTPUT
CLKOUT
PAOUT
(f
=
CLKOUT
f
/16)
XTAL
SOT23
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.