MAXIM MAX7044 Technical data

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 50Ω
load while only drawing 7.7mA at 2.7V.

The crystal-based architecture of the MAX7044 elimi­nates many of the common problems with SAW-based
transmitters by providing greater modulation depth,
faster frequency settling, higher tolerance of the trans­mit 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 microcon­troller 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.

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 50Ω Load

♦ Low 7.7mA (typ) Operating Supply Current*

♦ Uses Small, Low-Cost Crystal

♦ Small 3mm x 3mm 8-Pin SOT23 Package

♦ Fast-On Oscillator: 250µs 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

CLKOUTPAOUT

1

2

87XTAL2

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-

TOP MARK

MAX7044AKA-T

AEJW

查询MAX7044供应商

PACKAGE

-40°C to +125°C 8 SOT23-8

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 50Ω, VDD= +2.1V to +3.6V, TA= -40°C to +125°C, unless
otherwise noted. Typical values are at V

DD

= +2.7V, TA= +25°C, 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.

VDDto GND ..........................................................-0.3V to +4.0V

All Other Pins to GND ................................-0.3V to (V

DD

+ 0.3V)

Continuous Power Dissipation (T

A

= +70°C)

8-Pin SOT23 (derate 8.9mW/°C above +70°C)............714mW

Operating Temperature Range .........................-40°C to +125°C

Storage Temperature Range .............................-60°C to +150°C

Junction Temperature......................................................+150°C

Lead Temperature (soldering, 10s) .................................+300°C

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

PA on (Note 5)

fRF = 315MHz

PA off (Note 6) 1.7 2.8
V

DATA

at 50% duty

cycle, (Notes 3, 4)

8.0

PA on (Note 5)

Supply Current
(Note 2)

I

DD

fRF = 433MHz

PA off (Note 6) 1.9 3.1

mA

TA < +25°C 40 130

Standby Current I

STDBY

V

DATA

< VIL for
more than WAIT
time (Notes 4, 7)

T

A

< +125°C

nA

Frequency Range (Note 4) f

RF

450

MHz

Data Rate (Note 4) 0 100

kbps

Modulation Depth (Note 8) ON to OFF P

OUT

ratio 90 dB

TA = +25°C, VDD =
+2.7V

9.6

TA = +125°C, VDD =
+2.1V

5.9 9.0

Output Power, PA On
(Notes 4, 5)

P

OUT

fRF = 300MHz to
450MHz

T

A

= -40°C, VDD =

+3.6V

dBm

Oscillator settled to within 50kHz

Turn-On Time (Note 8) t

ON

Oscillator settled to within 5kHz

µs

fRF = 315MHz 48

Transmit Efficiency with CW
(Notes 5, 10)

f

RF

= 433MHz 47

%

fRF = 315MHz 43

Transmit Efficiency with 50%
OOK (Notes 3, 10)

f

RF

= 433MHz 41

%

14.1

13.8 25.4

14.4

300

13.1 15.8 18.5

14.0 25.7

550 2900

12.5 15.4

12.0

220
450

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 50Ω, VDD= +2.1V to +3.6V, TA= -40°C to +125°C, unless
otherwise noted. Typical values are at V

DD

= +2.7V, TA= +25°C, 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

= +25°C with fRF= 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

= VCC/2 + 100mV.

Note 6: PA output is turned off in test mode by V

DATA

= VCC/2 – 100mV.

Note 7: Wait time: t

WAIT

= (216x 32) / fRF.

Note 8: Generally limited by PC board layout.
Note 9: V

DATA

= VILto V

DATA

= VIHafter V

DATA

= VILfor WAIT time: t

WAIT

= (216 x 32) / fRF.

Note 10: V

DATA

= VIH. Efficiency = P

OUT

/(V

DD

x IDD).

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

PHASE-LOCKED LOOP (PLL)

VCO Gain

MHz/V

f

OFFSET

= 100kHz -80

fRF = 315MHz

f

OFFSET

= 1MHz -90

f

OFFSET

= 100kHz -77

Phase Noise

f

RF

= 433MHz

f

OFFSET

= 1MHz -87

dBc/Hz

fRF = 315MHz -50

Maximum Carrier Harmonics

f

RF

= 433MHz -50

dBc

fRF = 315MHz -74

Reference Spur

f

RF

= 433MHz -80

dBc

Loop Bandwidth 1.6

MHz

Crystal Frequency f

XTAL

MHz

Frequency Pulling by V

DD

3

ppm/V

Maximum Crystal Inductance 50 µH
Crystal Load Capacitance 3pF

DATA INPUT

Data Input High V

IH

V

DD

­V

Data Input Low V

IL

V

Maximum Input Current 10 µA
Pulldown Current 10 µA

CLKOUT OUTPUT

Output Voltage Low V

OL

I

SINK

= 650µA (Note 4)

V

Output Voltage High V

OH

I

SOURCE

= 350µA (Note 4)

V

DD

­V

Load Capacitance C

LOAD

(Note 4) 10 pF

CLKOUT Frequency

16

Hz

330

fRF/32

0.25

0.25

0.25

0.25

f

XTAL

/