Rainbow Electronics MAX7042 User Manual

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 low­noise amplifier (LNA), an image-rejection (IR) mixer, a
fully integrated phase-locked loop (PLL), local oscillator
(LO), 10.7MHz IF limiting amplifier with received-signal­strength 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.

Applications

Remote Keyless Entry

Tire-Pressure Monitoring

Home and Office Lighting Control

Remote Sensing

Smoke Alarms

Home Automation

Local Telemetry Systems

Security Systems

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

308MHz/315MHz/418MHz/433.92MHz

Low-Power, FSK Superheterodyne Receiver

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

19-3704; Rev 0; 5/05

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.

*EP = Exposed pad.

Typical Application Circuit appears at end of data sheet.

PART

MAX7042ATJ

TEMP

RANGE

-40°C to

+125°C

PIN-PACKAGE PKG CODE

32 Thin QFN-EP* 13255-3

TOP VIEW

24 23 22 21 20 19 18

N.C.

25

26

EN

27

FSEL1

FSEL2

28

29

HV

IN

30

DATA

LNASEL

31

32

N.C.

1234567

DVDDDGND

N.C.

N.C.

OP+

DF

MAX7042

N.C.

RSSI

THIN QFN

XTAL2

DS+

XTAL1

DS-

PDMAX

DD

AV

PDMIN

17

16

15

14

13

12

11

10

8

LNAIN

IFIN+

IFIN-

AGND

MIXOUT

MIXIN-

MIXIN+

LNAOUT

9

LNASRC

MAX7042

308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(Typical Application Circuit, 50Ω system impedance, AVDD= DVDD= HVIN= +2.4V to +3.6V, fRF= 308, 315, 418, and 433.92MHz;
T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at AVDD= DVDD= HVIN= +3.0V, fRF= 433.92MHz,

P

RFIN

≤ -80dBm, TA= +25°C, unless otherwise noted.)

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.

HVINto AGND or DGND .......................................-0.3V to +6.0V

AVDD, DVDDto 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

Supply Voltage (3V) V

Supply Voltage (5V) HV

Supply Current I

Shutdown Current (3V) I

Startup Time t

DIGITAL I/O

Input High Threshold V

Input Low Threshold V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

HVIN, AVDD, and DVDD connected

DD

to power supply

HVIN connected to power supply,
AV

IN

DD

SHDN

SHDN

ON

IH

IL

and DVDD unconnected from

DD

, but connected together

HV

IN

315M H z ( 3V )

315M H z ( 5V )

434M H z ( 3V )

434M H z ( 5V )

All digital
inputs low

All digital
inputs low

Time from EN = high to final signal
detection; does not include
baseband filter or data­slicer reference settling

2.4 3.0 3.6 V

4.5 5.0 5.5 V

Operating, 1x I

Operating, 2x I

Operating, 1x I

Operating, 2x I

Operating, 1x I

Operating, 2x I

Operating, 1x I

Operating, 2x I

TA = +25°C 0.02

TA = +85°C 0.1

T

= +125°C 0.85 6

A

TA = +25°C 0.6

TA = +85°C 1.4Shutdown Current (5V) I

= +125°C 4 7

T

A

LNA

LNA

LNA

LNA

LNA

LNA

LNA

LNA

0.9 x HV

6.2

6.8

6.4

7.0

6.4 8.7

7.0 8.6

6.6 8.4

7.2 9.2

250 µs

IN

0.1 x HV

IN

mA

µA

µA

V

V

MAX7042

308MHz/315MHz/418MHz/433.92MHz

Low-Power, FSK Superheterodyne Receiver

_______________________________________________________________________________________ 3

DC ELECTRICAL CHARACTERISTICS (continued)

(Typical Application Circuit, 50Ω system impedance, AVDD= DVDD= HVIN= +2.4V to +3.6V, fRF= 308, 315, 418, and 433.92MHz;
T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at AVDD= DVDD= HVIN= +3.0V, fRF= 433.92MHz,

P

RFIN

≤ -80dBm, TA= +25°C, unless otherwise noted.)

AC ELECTRICAL CHARACTERISTICS

(Typical Application Circuit, 50Ω system impedance, AVDD= DVDD= HVIN= +2.4V to +3.6V, fRF= 308, 315, 418, and 433.92MHz;
T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at AVDD= DVDD= HVIN= +3.0V, fRF= 433.92MHz,

P

RFIN

≤ -80dBm, TA= +25°C, unless otherwise noted.)

Input High Pulldown Current I

Input Low-Leakage Current I

Output High Voltage V

Output Low Voltage V

VOLTAGE REGULATOR

Output Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

HVIN = +3.6V 8 15

IH

HVIN = +5.5V 20 40

HVIN = +3.6V <1 1

IL

HVIN = +5.5V <1 1

OHISOURCE

I

OL

REG

= 500µA HVIN - 0.4 V

= 500µA 0.4 V

SINK

2.5 3.0 3.5 V

µA

µA

Maximum Input Level 0 dBm

Sensitivity (Note 1)

Receiver Image Rejection 45 dB

LNA/MIXER

Input Impedance (Note 2) Z

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

Voltage Conversion Gain

IF LIMITING AMPLIFIER

Input Impedance Z

-3dB Bandwidth 10 MHz

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

P

IIP3

11

1dB

MIX

11

315MHz
setting

434MHz
setting

Normalized to
50Ω

1x I

315MHz -47

LNA

2x I

315MHz -52

LNA

1x I

315MHz -37

LNA

2x I

315MHz -42

LNA

330Ω IF filter
load
(Notes 2, 3)

Operating, 1x I

Operating, 2x I

Operating, 1x I

Operating, 2x I

2x I

LNA

2x I

LNA

1x I

LNA

2x I

LNA

1x I

LNA

2x I

LNA

LNA

LNA

LNA

LNA

315MHz 0.94 - j3.2

433.92MHz 0.94 - j2.1

315MHz 52

315MHz 57

433.92MHz 47

433.92MHz 52

-107

-110

-106

-109

-80 dBm

330 Ω

330 Ω

dBm

dBm

dBm

dB

MAX7042

308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver

4 _______________________________________________________________________________________

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 con­nected 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.

AC ELECTRICAL CHARACTERISTICS (continued)

(Typical Application Circuit, 50Ω system impedance, AVDD= DVDD= HVIN= +2.4V to +3.6V, fRF= 308, 315, 418, and 433.92MHz;
T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at AVDD= DVDD= HVIN= +3.0V, fRF= 433.92MHz,

P

RFIN

≤ -80dBm, TA= +25°C, unless otherwise noted.)

Typical Operating Characteristics

(Typical Application Circuit, VDD= 3.0V, fRF= 433.92MHz, IF BW = 280kHz, data rate = 4kbps Manchester encoded, frequency
deviation = ±50kHz, BER = 0.2%, T

A

= +25°C, unless otherwise noted.)

Operating Frequency f

RSSI Slope 10 16 21 mV/dB

FSK DEMODULATOR

Conversion Gain 1.1 2.1 3.0 mV/kHz

ANALOG BASEBAND

M axi m um P eak- D etector Band w i d th 50 kHz

Maximum Data-Filter Bandwidth BW

Maximum Data-Slicer Bandwidth BW

Maximum Data Rate

CRYSTAL OSCILLATOR

Crystal Frequency f

Crystal Load Capacitance 4.5 pF

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IF

DF

DS

10.7 MHz

50 kHz

100 kHz

Manchester coded 33

NRZ 66

XTAL

(fRF - 10.7)

/ 32

kHz

MHz

SUPPLY CURRENT vs. SUPPLY VOLTAGE

7.2

7.0

6.8

6.6

6.4

6.2

6.0

SUPPLY CURRENT (mA)

5.8

5.6

5.4

+85°C

2.4 3.02.7 3.3 3.6
SUPPLY VOLTAGE (V)

(1x I

+125°C

-40°C

LNA

)

+25°C

SUPPLY CURRENT vs. SUPPLY VOLTAGE

(2x I

8.0

7.8

MAX7042 toc01

7.6

7.4

7.2

7.0

6.8

6.6

SUPPLY CURRENT (mA)

6.4

6.2

6.0

+85°C

2.4 3.02.7 3.3 3.6
SUPPLY VOLTAGE (V)

+125°C

LNA

+25°C

)

-40°C

7.0

6.8

MAX7042 toc02

6.6

6.4

6.2

SUPPLY CURRENT (mA)

6.0

5.8

5.6

SUPPLY CURRENT vs. RF FREQUENCY

)

(1x I

LNA

+125°C

+85°C

+25°C

-40°C

300 350 375325 400 425 450

RF FREQUENCY (MHz)

MAX7042 toc03

MAX7042

308MHz/315MHz/418MHz/433.92MHz

Low-Power, FSK Superheterodyne Receiver

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(Typical Application Circuit, VDD= 3.0V, fRF= 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

7.5

7.3

7.1

6.9

6.7

SUPPLY CURRENT (mA)

6.5

6.3

6.1
300 350 375325 400 425 450

RF FREQUENCY (MHz)

(2x I

+125°C

+85°C

+25°C

-40°C

LNA

)

BIT-ERROR RATE vs. AVERAGE INPUT POWER

)

(2x I

100

10

LNA

fRF = 433.92MHz

DEEP-SLEEP CURRENT vs. TEMPERATURE

1000

MAX7042 toc04

800

600

400

DEEP-SLEEP CURRENT (nA)

200

0

-40

TEMPERATURE (°C)

SENSITIVITY vs. TEMPERATURE

(1x I

-103

-104

MAX7042 toc07

-105

VCC = +3.6V

VCC = +3.0V

VCC = +2.4V

)

LNA

BIT-ERROR RATE vs. AVERAGE INPUT POWER

)

(1x I

100

MAX7042 toc05

11085603510-15

10

1

0.2% BER

BIT-ERROR RATE

0.1

0.01

-114 -104

fRF = 315MHz

-112
AVERAGE INPUT POWER (dBm)

LNA

fRF = 433.92MHz

-108-110

-106

SENSITIVITY vs. TEMPERATURE

)

(2x I

LNA

MAX7042 toc08

-106

-107

-108

MAX7042 toc06

MAX7042 toc09

1

0.2% BER

BIT-ERROR RATE

0.1

fRF = 315MHz

0.01

-115

-117 -107
AVERAGE INPUT POWER (dBm)

-109-113 -111

SENSITIVITY

vs. FREQUENCY DEVIATION

-100

-102

-104

-106

SENSITIVITY (dBm)

-108

-110

-112
1100

FREQUENCY DEVIATION IS
MEASURED FROM 0 TO PEAK

10

FREQUENCY DEVIATION (kHz)

MAX7042 toc10

-106

fRF = 433.92MHz

SENSITIVITY (dBm)

-107

-108
fRF = 315MHz

-109

vs. IF INPUT POWER

1.8

1.5

1.2

0.9

RSSI (V)

0.6

0.3

0

-90 -50 -30-70 -10 10

TEMPERATURE (°C)

RSSI AND DELTA

RSSI

RF INPUT POWER (dBm)

DELTA

11085603510-15-40

MAX7042 toc11

-109

SENSITIVITY (dBm)

-110

-111

-112

3

2

1

0

-1

-2

-3

2.0

1.6

1.2

DELTA (%)

0.8

0.4

FSK DEMODULATION OUTPUT (V)

0

10.3 10.5 10.610.4 10.810.7 10.9 11.0

fRF = 433.92MHz

fRF = 315MHz

11085603510-15-40

TEMPERATURE (°C)

FSK DEMODULATOR OUTPUT

vs. IF FREQUENCY

MAX7042 toc12

IF FREQUENCY (MHz)

MAX7042

308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Typical Application Circuit, VDD= 3.0V, fRF= 433.92MHz, IF BW = 280kHz, data rate = 4kbps Manchester encoded, frequency
deviation = ±50kHz, BER = 0.2%, T

A

= +25°C, unless otherwise noted.)

SYSTEM GAIN vs. IF FREQUENCY

(1x I

50

40

30

20

SYSTEM GAIN (dB)

10

0

45dB IMAGE

UPPER SIDEBAND

REJECTION

)

LNA

FROM RFIN

TO MIXOUT

= 433.92MHz

f

RF

LOWER SIDEBAND

MAX7042 toc13

SYSTEM GAIN (dB)

SYSTEM GAIN vs. IF FREQUENCY

60

50

40

30

20

10

0

45dB IMAGE

REJECTION

(2x I

LNA

UPPER SIDEBAND

)

FROM RFIN

TO MIXOUT

= 433.92MHz

f

RF

LOWER SIDEBAND

60

50

MAX7042 toc14

40

30

20

IMAGE REJECTION (dB)

10

IMAGE REJECTION vs. TEMPERATURE

(1x I

LNA

fRF = 433.92MHz

fRF = 315MHz

)

MAX7042 toc15

-10
030

IF FREQUENCY (MHz)

252015105

-10
030

IF FREQUENCY (MHz)

IMAGE REJECTION vs. TEMPERATURE

)

(2x I

60

fRF = 433.92MHz

50

fRF = 315MHz

40

30

20

IMAGE REJECTION (dB)

10

0

LNA

MAX7042 toc16

11085603510-15-40

TEMPERATURE (°C)

S11 vs. RF FREQUENCY

0

-4

252015105

NORMALIZED IF GAIN

vs. IF FREQUENCY

0

-3

-6

-9

-12

NORMALIZED IF GAIN (dB)

-15

-18
1

IF FREQUENCY (MHz)

MAX7042 toc18

0

TEMPERATURE (°C)

MAX7042 toc17

10

100

11085603510-15-40

-8

S11 (dB)

433.92MHz

-12

-16
100 1000

RF FREQUENCY (MHz)

850700550400250