MAXIM MAX7031 Technical data

General Description

The MAX7031 crystal-based, fractional-N transceiver is
designed to transmit and receive FSK data at factory­preset carrier frequencies of 308MHz†, 315MHz, or

433.92MHz with data rates up to 33kbps (Manchester
encoded) or 66kbps (NRZ encoded). This device gen­erates a typical output power of +10dBm into a 50Ω
load, and exhibits typical sensitivity of -110dBm. The
MAX7031 features separate transmit and receive pins
(PAOUT and LNAIN) and provides an internal RF switch
that can be used to connect the transmit and receive
pins to a common antenna.

The MAX7031 transmit frequency is generated by a 16­bit, fractional-N, phase-locked loop (PLL), while the
receiver’s local oscillator (LO) is generated by an inte­ger-N PLL. This hybrid architecture eliminates the need
for separate transmit and receive crystal reference
oscillators because the fractional-N PLL is preset to be

10.7MHz above the receive LO. Retaining the fixed-N
PLL for the receiver avoids the higher current-drain
requirements of a fractional-N PLL and keeps the
receiver current drain as low as possible.

The fractional-N architecture of the MAX7031 transmit
PLL allows the transmit FSK signal to be preset for
exact frequency deviations, and completely eliminates
the problems associated with oscillator-pulling FSK sig­nal generation. All frequency-generation components
are integrated on-chip, and only a crystal, a 10.7MHz IF
filter, and a few discrete components are required to
implement a complete antenna/digital data solution.

The MAX7031 is available in a small, 5mm x 5mm, 32­pin, thin QFN package, and is specified to operate in
the automotive -40°C to +125°C temperature range.

†

Consult factory for availability.

Applications

2-Way Remote Keyless Entry

Security Systems

Home Automation

Remote Controls

Remote Sensing

Smoke Alarms

Garage-Door Openers

Local Telemetry Systems

Features

o +2.1V to +3.6V or +4.5V to +5.5V Single-Supply

Operation

o Single-Crystal Transceiver

o Factory-Preset Frequency (No Serial Interface

Required)

o FSK Modulation

o Factory-Preset FSK Frequency Deviation

o +10dBm Output Power into 50Ω Load

o Integrated TX/RX Switch

o Integrated Transmit and Receive PLL, VCO, and

Loop Filter

o > 45dB Image Rejection

o Typical RF Sensitivity*: -110dBm

o Selectable IF Bandwidth with External Filter

o RSSI Output with High Dynamic Range

o < 12.5mA Transmit-Mode Current

o < 6.7mA Receive-Mode Current

o < 800nA Shutdown Current

o Fast-On Startup Feature, < 250µs

o Small, 32-Pin, Thin QFN Package

MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz

FSK Transceiver with Fractional-N PLL

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-3707; Rev 3; 11/10

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.

*

0.2% BER, 4kbps Manchester-encoded data, 280kHz IF BW

+

Denotes a lead(Pb)-free/RoHs-compliant package.

**

EP = Exposed pad.
Note: The MAX7031 is available with factory-preset operating
frequencies. See the Selector Guide for complete part num­bers.

Pin Configuration, Selector Guide, Typical Application
Circuit, and Functional Diagram appear at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX7031_ATJ__+ -40°C to +125°C 32 Thin QFN-EP**

MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz

FSK Transceiver with Fractional-N PLL

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

HVIN to GND .........................................................-0.3V to +6.0V

PAVDD, AVDD, DVDD to GND..............................-0.3V to +4.0V

ENABLE, T/R, DATA, AGC0, AGC1,

AUTOCAL to GND ...............................-0.3V to (V

HVIN

+ 0.3)V

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

_VDD

+ 0.3)V

Continuous Power Dissipation (T

A

= +70°C)
32-Pin Thin QFN (derate 21.3mW/°C

above +70°C).............................................................1702mW

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

Storage Temperature Range .............................-65°C to +150°C

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

Soldering Temperature (reflow) .......................................+260°C

DC ELECTRICAL CHARACTERISTICS

(

Typical Application Circuit

, 50Ω system impedance, V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.1V to +3.6V, fRF= 308MHz, 315MHz, or

433.92MHz, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.7V,

T

A

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage (3V Mode) V

Supply Voltage (5V Mode) V

Supply Current I

Voltage Regulator V

DIGITAL I/O

Input-High Threshold V

Input-Low Threshold V

Pulldown Sink Current

Output Low Voltage V

Output High Voltage V

DD

HVIN

HVIN, PAVDD, AVDD, and DVDD
connected to power supply

PAVDD, AVDD, and DVDD unconnected
from HVIN, but connected together

Transmit mode
(Note 2)

TA < +85°C,
typ at +25°C

DD

(Note 3)

TA < +125°C,
typ at +125°C
(Note 2)

REG

V

HVIN

(Note 2)

IH

(Note 2)

IL

AGC0-1, AUTOCAL, ENABLE, T/R, DATA
(V

OL

OH

I

SINK

I

SOURCE

fRF = 315MHz 11.6 19.1

f

= 434MHz 12.4 20.4

RF

Receiver 315MHz 6.4 8.4

Receiver 434MHz 6.7 8.7

Deep-sleep (3V mode) 0.8 8.8

Deep-sleep (5V mode) 2.4 10.9

Receiver 315MHz 6.8 8.7

Receiver 434MHz 7.0 8.8

Deep-sleep (3V mode) 8.0 34.2

Deep-sleep (5V mode) 14.9 39.3

HVIN

= 5V, I

= 5.5V)

= 15mA 3.0 V

LOAD

= 500µA 0.15 V

= 500µA

2.1 2.7 3.6 V

4.5 5.0 5.5 V

0.9 x

V

HVIN

0.1 x

V

HVIN

20 µA

V

HVIN

- 0.26

mA

µA

mA

µA

V

V

V

MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz

FSK Transceiver with Fractional-N PLL

_______________________________________________________________________________________ 3

AC ELECTRICAL CHARACTERISTICS

(

Typical Application Circuit

, 50Ω system impedance, V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.1V to +3.6V, fRF= 308MHz, 315MHz. or

433.92MHz, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.7V,

T

A

= +25°C, unless otherwise noted.) (Note 1)

GENERAL CHARACTERISTICS

Frequency Range 308/315/433.92 MHz
Maximum Input Level P

Transmit Efficiency (Note 5)

Power-On Time t

RECEIVER

Sensitivity

Image Rejection 46 dB

POWER AMPLIFIER

Output Power P

Maximum Carrier Harmonics With output matching network -40 dBc

Reference Spur -50 dBc

PHASE-LOCKED LOOP

Transmit VCO Gain K

Transmit PLL Phase Noise

Receive VCO Gain 340 MHz/V

Receive PLL Phase Noise

Loop Bandwidth

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

RFIN

fRF = 315MHz 32

f

RF

ENABLE or T/R transition low to high,
transmitter frequency settled to within
50kHz of the desired carrier

ENABLE or T/R transition low to high,

ON

OUT

VCO

transmitter frequency settled to within 5kHz
of the desired carrier

ENABLE transition low to high, or T/R
transition high to low, receiver startup time
(Note 4)

0.2% BER, 4kbps
Manchester data rate,
280kHz IF BW, FSK
±50kHz deviation

TA = +25°C (Note 3) 4.6 10.0 15.5

TA = +125°C, V
V

TA = -40°C, V
V

10kHz offset, 200kHz loop BW -68

1MHz offset, 200kHz loop BW -98

10kHz offset, 500kHz loop BW -80

1MHz offset, 500kHz loop BW -90

Transmit PLL 200

Receive PLL 500

= 434MHz 30

= +2.1V (Note 2)

HVIN

= +3.6V (Note 3)

HVIN

PAVDD

PAVDD

= V

315MHz -110

434MHz -107

= V

AVDD

= V

AVDD

= V

DVDD

DVDD

=

=

3.9 6.7

0 dBm

200

350

250

13.1 15.8

340 MHz/V

dBc/Hz

dBc/Hz

%

µs

dBm

dBm

kHz

MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz

FSK Transceiver with Fractional-N PLL

4 _______________________________________________________________________________________

AC ELECTRICAL CHARACTERISTICS (continued)

(

Typical Application Circuit

, 50Ω system impedance, V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.1V to +3.6V, fRF= 308MHz, 315MHz. or

433.92MHz, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.7V,

T

A

= +25°C, unless otherwise noted.) (Note 1)

Reference Frequency Input Level 0.5 V

LOW-NOISE AMPLIFIER/MIXER (Note 7)

LNA Input Impedance Z

Voltage-Conversion Gain

Input-Referred 3rd-Order
Intercept Point

Mixer Output Impedance 330 Ω

LO Signal Feedthrough to
Antenna

RSSI

Input Impedance 330 Ω

Operating Frequency f

3dB Bandwidth 10 MHz

Gain 15 mV/dB

FSK DEMODULATOR

Conversion Gain 2.0 mV/kHz

ANALOG BASEBAND

Maximum Data Filter Bandwidth 50 kHz

Maximum Data Slicer Bandwidth 100 kHz

Maximum Peak Detector
Bandwidth

Maximum Data Rate

CRYSTAL OSCILLATOR

Crystal Frequency f

Frequency Pulling by V

Crystal Load Capacitance (Note 6) 4.5 pF

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

INLNA

IIP3

IF

XTAL

DD

Normalized to 50Ω

High-gain state

Low-gain state

High-gain state -42

Low-gain state -6

Manchester coded 33

Nonreturn to zero (NRZ) 66

fRF = 315MHz 1 - j4.7

= 434MHz 1 - j3.3

f

RF

fRF = 315MHz 50

= 434MHz 45

f

RF

fRF = 315MHz 13

= 434MHz 9

f

RF

-100 dBm

10.7 MHz

50 kHz

(fRF - 10.7)

/ 24

2 ppm/V

P-P

dB

dBm

kbps

MHz

MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz

FSK Transceiver with Fractional-N PLL

_______________________________________________________________________________________ 5

AC ELECTRICAL CHARACTERISTICS (continued)

(

Typical Application Circuit

, 50Ω system impedance, V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.1V to +3.6V, fRF= 308MHz, 315MHz. or

433.92MHz, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V

PAV

DD

= V

AV

DD

= V

DV

DD

= V

HV

IN

= +2.7V,

T

A

= +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: 100% tested at T

A

= +125°C. Guaranteed by design and characterization over temperature.

Note 3: Guaranteed by design and characterization. Not production tested.
Note 4: Time for final signal detection; does not include baseband filter settling.
Note 5: Efficiency = P

OUT

/(VDDx IDD).

Note 6: Dependent on PCB trace capacitance.
Note 7: Input impedance is measured at the LNAIN pin. Note that the impedance at 315MHz includes the 12nH inductive degenera-

tion from the LNA source to ground. The impedance at 434MHz includes a 10nH inductive degeneration connected from the
LNA source to ground. The equivalent input circuit is 50Ω in series with ~2.2pF. The voltage conversion is measured with
the LNA input-matching inductor, the degeneration inductor, and the LNA/mixer tank in place, and does not include the IF
filter insertion loss.

Typical Operating Characteristics

(

Typical Operating Circuit

, V

PAVDD

= V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 433.92MHz, IF BW = 280kHz. 4kbps Manchester

encoded, 0.2% BER deviation = ±50kHz, TA= +25°C, unless otherwise noted.)

SUPPLY CURRENT vs. SUPPLY VOLTAGE

MAX7031 toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

3.33.02.72.4

6.2

6.4

6.6

6.8

7.0

7.2

7.4

6.0

2.1 3.6

+85°C

+125°C

+25°C

-40°C

SUPPLY CURRENT vs. RF FREQUENCY

FSK MODE

MAX7030 toc02

RF FREQUENCY (MHz)

SUPPLY CURRENT (mA)

425400325 350 375

6.5

6.6

6.7

6.8

6.9

7.0

6.4
300 450

+85°C

+125°C

+25°C

-40°C

DEEP-SLEEP CURRENT vs. TEMPERATURE

MAX7031 toc03

TEMPERATURE (°C)

DEEP-SLEEP CURRENT (µA)

1108535 60-10-15

2

4

6

8

10

12

14

16

18

0

-40

VCC = +3.6V

VCC = +3.0V

VCC = +2.1V

RECEIVER

MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz

FSK Transceiver with Fractional-N PLL

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(

Typical Operating Circuit

, V

PAVDD

= V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 433.92MHz, IF BW = 280kHz. 4kbps Manchester

encoded, 0.2% BER deviation = ±50kHz, T

A

= +25°C, unless otherwise noted.)

RECEIVER

BIT-ERROR RATE

vs. AVERAGE INPUT POWER

100

280kHz IF BW

10

1

BIT-ERROR RATE (%)

0.2% BER

0.1

fRF = 315MHz

0.01

-116 -104
AVERAGE INPUT POWER (dBm)

-108 -106-110-112-114

fRF = 434MHz

MAX7031 toc04

-100

-102

-104

-106

SENSITIVITY (dBm)

-108

-110

-112

SENSITIVITY vs. TEMPERATURE

280kHz IF BW

0.2% BER

-40
TEMPERATURE (°C)

fRF = 434MHz

fRF = 315MHz

SENSITIVITY vs. FREQUENCY DEVIATION

-94

MAX7031 toc05

11085603510-15

-96

-98

-100

-102

SENSITIVITY (dBm)

-104

-106

-108
1 100

FREQUENCY DEVIATION (kHz)

10

280kHz IF BW

0.2% BER

MAX7031 toc06

1.8

1.6

1.4

HIGH-GAIN MODE

1.2

1.0

RSSI (V)

0.8

0.6

0.4

0.2
AGC HYSTERESIS: 3dB

0

-130 10
RF INPUT POWER (dBm)

AGC SWITCH
POINT

LOW-GAIN MODE

MAX7031 toc07

-10-30-70 -50-90-110

SYSTEM GAIN vs. IF FREQUENCY

50

RSSI vs. RF INPUT POWER

40

30

20

10

SYSTEM GAIN (dBm)

0

-10

-20

45dB IMAGE

REJECTION

030

IF FREQUENCY (MHz)

UPPER SIDEBAND

FROM RFIN

TO MIXOUT

= 434MHz

f

RF

LOWER SIDEBAND

252015105

MAX7031 toc10

RSSI AND DELTA vs. IF INPUT POWER

2.1

1.8

1.5

1.2

RSSI (V)

0.9

0.6

0.3

0

-90 10

IMAGE REJECTION vs. TEMPERATURE

48

46

44

IMAGE REJECTION (dB)

42

-40

RSSI

IF INPUT POWER (dBm)

fRF = 315MHz

TEMPERATURE (°C)

MAX7031 toc08

DELTA

-10-30-50-70

fRF = 434MHz

11085603510-15

3.5

2.5

1.5

0.5

-0.5

-1.5

-2.5

-3.5

MAX7031 toc11

1.6

1.2

0.8

DELTA (%)

0.4

FSK DEMODULATOR OUTPUT (V)

0

10.4 11.0

NORMALIZED IF GAIN vs. IF FREQUENCY

0

-4

-8

-12

NORMALIZED IF GAIN (dB)

-16

-20
1 100

FSK DEMODULATOR OUTPUT

vs. IF FREQUENCY

MAX7031 toc09

10.910.810.710.610.5

IF FREQUENCY (MHz)

MAX7031 toc12

10

IF FREQUENCY (MHz)