MAXIM MAX1471 Technical data

General Description

The MAX1471 low-power, CMOS, superheterodyne, RF
dual-channel receiver is designed to receive both ampli­tude-shift-keyed (ASK) and frequency-shift-keyed (FSK)
data without reconfiguring the device or introducing any
time delay normally associated with changing modula­tion schemes. The MAX1471 requires few external com­ponents to realize a complete wireless RF digital data
receiver for the 300MHz to 450MHz ISM bands.

The MAX1471 includes all the active components
required in a superheterodyne receiver including: a low­noise amplifier (LNA), an image-reject (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 voltage regulator. Differential peak-detecting
data demodulators are included for both the FSK and
ASK analog baseband data recovery. The MAX1471
includes a discontinuous receive (DRX) mode for low­power operation, which is configured through a serial
interface bus.

The MAX1471 is available in a 32-pin thin QFN package
and is specified over the automotive -40°C to +125°C
temperature range.

Applications

Automotive Remote Keyless Entry (RKE)

Tire Pressure Monitoring Systems

Garage Door Openers

Wireless Sensors

Wireless Keys

Security Systems

Medical Systems

Home Automation

Local Telemetry Systems

Features

o ASK and FSK Demodulated Data on Separate

Outputs

o Specified over Automotive -40°C to +125°C

Temperature Range

o Low Operating Supply Voltage Down to 2.4V

o On-Chip 3V Regulator for 5V Operation

o Low Operating Supply Current

7mA Continuous Receive Mode

1.1µA Deep-Sleep Mode

o Discontinuous Receive (DRX) Low-Power

Management

o Fast-On Startup Feature < 250µs

o Integrated PLL, VCO, and Loop Filter

o 45dB Integrated Image Rejection

o RF Input Sensitivity*

ASK: -114dBm
FSK: -108dBm

o Selectable IF BW with External Filter

o Programmable Through Serial User Interface

o RSSI Output and High Dynamic Range with AGC

MAX1471

315MHz/434MHz Low-Power, 3V/5V

ASK/FSK Superheterodyne Receiver

________________________________________________________________

Maxim Integrated Products

1

Pin Configuration

19-3272; Rev 4; 9/11

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

Ordering Information

+

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

/V denotes an automotive qualified part.

**

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX1471ATJ/V+ -40°C to +125°C 32 Thin QFN-EP**

TOP VIEW

HVIN

MIXIN-

SCLK

MIXOUT

DIO

AGND

CS

IFIN-

FDATA

25

DVDD

24

23

DGND

22

DFF

21

OPF+

20

DSF+

19

DSF-

PDMAXF

18

17

PDMINF

16

IFIN+

DSA-

DSA+

OPA+

DFA

XTAL2

XTAL1

AVDD

LNAIN

ADATA

PDMINA

PDMAXA

32+31 30 29 28 27 26

1

2

3

4

LNAOUT

MAX1471

MIXIN+

THIN QFN

5

6

7

8

9 101112131415

LNASRC

MAX1471

315MHz/434MHz Low-Power, 3V/5V
ASK/FSK Superheterodyne Receiver

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.

High-Voltage Supply, HVIN to DGND ......................-0.3V, +6.0V

Low-Voltage Supply, AVDD and DVDD to AGND ....-0.3V, +4.0V

SCLK, DIO, CS, ADATA,

FDATA ...................................(DGND - 0.3V) to (HVIN + 0.3V)

All Other Pins............................(AGND - 0.3V) to (AVDD + 0.3V)

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

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

, V

AVDD

= V

DVDD

= V

HVIN

= +2.4V to +3.6V, fRF= 300MHz to 450MHz, TA= -40°C to +125°C, unless other-

wise noted. Typical values are at V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434 MHz, TA= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

GENERAL CHARACTERISTICS

Supply Voltage (5V) HVIN

Supply Voltage (3V) V

Supply Current I

Startup Time t

DIGITAL OUTPUTS (DIO, ADATA, FDATA)

Output High Voltage V

Output Low Voltage V

DIGITAL INPUTS (CS, DIO, SCLK)

Input High Threshold V

Input Low Threshold V

DD

ON

DD

OH

OL

IH

IL

AVDD and DVDD unconnected from HVIN,
but connected together

HVIN, AVDD, and DVDD connected to
power supply

TA < +85°C

TA < +105°C
(Note 2)

TA < +125°C
(Note 2)

Time for final signal detection, does not
include baseband filter settling (Note 2)

I

I

= 250µA (Note 2)

SOURCE

= 250µA (Note 2) 0.15 V

SINK

4.5 5.0 5.5 V

2.4 3.0 3.6 V

Operating 7.0 8.4 mA

Polling duty cycle: 10%
duty cycle

DRX mode OFF current 5.0 14.2

Deep-sleep current 1.1 7.1

Operating 8.5 mA

Polling duty cycle: 10%
duty cycle

DRX mode OFF current 15.5

Deep-sleep current 13.4

Operating 8.6 mA

Polling duty cycle: 10%
duty cycle

DRX mode OFF current 44.1

Deep-sleep current 36.4

0.9 x

V

HVIN

705 855

200 250 µs

V

-

HVIN

0.15

.

865

900

0.1 x

V

HVIN

µA

µA

µA

V

V

V

MAX1471

315MHz/434MHz Low-Power, 3V/5V

ASK/FSK Superheterodyne Receiver

_______________________________________________________________________________________ 3

DC ELECTRICAL CHARACTERISTICS (continued)

(

Typical Application Circuit

, V

AVDD

= V

DVDD

= V

HVIN

= +2.4V to +3.6V, fRF= 300MHz to 450MHz, TA= -40°C to +125°C, unless other-

wise noted. Typical values are at V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434 MHz, TA= +25°C, unless otherwise noted.) (Note 1)

AC ELECTRICAL CHARACTERISTICS

(

Typical Application Circuit

, V

AVDD

= V

DVDD

= V

HVIN

= +2.4V to +3.6V, fRF= 300MHz to 450MHz, TA= -40°C to +125°C, unless other-

wise noted. Typical values are at V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434 MHz, TA= +25°C, unless otherwise noted.) (Note 1)

PARAMETER

CONDITIONS

UNITS

GENERAL CHARACTERISTICS

ASK

Receiver Sensitivity RF

IN

0.2% BER, 4kbps
Manchester Code, 280kHz
IF BW, 50Ω

FSK

dBm

Maximum Receiver Input Power
Level

RF

MAX

0

dBm

Receiver Input Frequency Range

f

RF

450

MHz

Receiver Image Rejection IR (Note 3) 45 dB

LNA/MIXER (Note 4)

LNA Input Impedance

Normalized to 50Ω

Voltage Conversion Gain (High­Gain Mode)

dB

Input-Referred 3rd-Order

Intercept Point (High-Gain Mode)

-38

dBm

Voltage Conversion Gain (Low­Gain Mode)

dB

Input-Referred 3rd-Order

Intercept Point (Low-Gain Mode)

-5

dBm

LO Signal Feedthrough to
Antenna

-90

dBm

Mixer Output Impedance

Ω

IF

Input Impedance Z

IN_IF

Ω

Operating Frequency f

IF

MHz

3dB Bandwidth 10

MHz

FM DEMODULATOR

Demodulator Gain G

FM

2.2

mV/kHz

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input-High Leakage Current I

Input-Low Leakage Current I

Input Capacitance C

VOLTAGE REGULATOR

Output Voltage V

REG

IH

IL

IN

(Note 2) -20 µA

(Note 2) 20 µA

(Note 2) 2.0 pF

V

HVIN

= 5.0V, I

= 7.0mA 3.0 V

LOAD

SYMBOL

Z

IN_LNA

MIN TYP MAX

-114

-108

300

fRF = 315MHz 1 - j4.7

fRF = 434MHz 1 - j3.4

47.5

12.2

Z

OUT_MIX

330

330

10.7

MAX1471

315MHz/434MHz Low-Power, 3V/5V
ASK/FSK Superheterodyne Receiver

4 _______________________________________________________________________________________

AC ELECTRICAL CHARACTERISTICS (continued)

(

Typical Application Circuit

, V

AVDD

= V

DVDD

= V

HVIN

= +2.4V to +3.6V, fRF= 300MHz to 450MHz, TA= -40°C to +125°C, unless other-

wise noted. Typical values are at V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434 MHz, TA= +25°C, unless otherwise noted.) (Note 1)

Note 1: Production tested at TA= +85°C. Guaranteed by design and characterization over entire temperature range.
Note 2: Guaranteed by design and characterization. Not production tested.
Note 3: The oscillator register (0x3) is set to the nearest integer result of f

XTAL

/ 100kHz (see the

Oscillator Frequency Register

section).

Note 4: Input impedance is measured at the LNAIN pin. Note that the impedance at 315MHz includes the 15nH inductive degeneration

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 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.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

ANALOG BASEBAND

Maximum Data Filter Bandwidth BW

Maximum Data Slicer Bandwidth BW

Maximum Peak Detector
Bandwidth

Maximum Data Rate

CRYSTAL OSCILLATOR

Crystal Frequency f

Frequency Pulling by V

Crystal Load Capacitance 3pF

DIGITAL INTERFACE TIMING (see Figure 8)

Minimum SCLK Setup to Falling
Edge of CS

Minimum CS Falling Edge to
SCLK Rising-Edge Setup Time

Minimum CS Idle Time t
Minimum CS Period t

Maximum SCLK Falling Edge to
Data Valid Delay

Minimum Data Valid to SCLK
Rising-Edge Setup Time

Minimum Data Valid to SCLK
Rising-Edge Hold Time

Minimum SCLK High Pulse Width t

Minimum SCLK Low Pulse Width t
Minimum CS Rising Edge to

SCLK Rising-Edge Hold Time

Maximum CS Falling Edge to
Output Enable Time

Maximum CS Rising Edge to
Output Disable Time

DD

BW

XTAL

t

SC

t

CSS

CSI

CS

t

DO

t

DS

t

DH

CH

CL

t

CSH

t

DV

t

TR

DF

DS

PD

Manchester coded 33

Nonreturn to zero (NRZ) 66

50 kHz

100 kHz

50 kHz

kbps

9.04 13.728 MHz

3 ppm/V

30 ns

30 ns

125 ns

2.125 µs

80 ns

30 ns

30 ns

100 ns

100 ns

30 ns

25 ns

25 ns

MAX1471

315MHz/434MHz Low-Power, 3V/5V

ASK/FSK Superheterodyne Receiver

_______________________________________________________________________________________

5

1

)

)

0

)

)

MAX1471 t 06

(°C)

0

0

Typical Operating Characteristics

(

Typical Application Circuit

, V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434MHz, TA= +25°C, unless otherwise noted.)

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

8.0

+105°C

7.6

7.2

6.8

SUPPLY CURRENT (mA)

6.4

6.0

2.4 2.7 3.0 3.3 3.6

+85°C

-40°C

SUPPLY VOLTAGE (V)

BIT-ERROR RATE

vs. AVERAGE INPUT POWER (ASK DATA

100

280kHz IF BW

10

fRF = 434MHz

+125°C

+25°C

MAX1471 toc01

SUPPLY CURRENT

vs. RF FREQUENCY

8.0

7.8

7.6

7.4

7.2

7.0

6.8

6.6

SUPPLY CURRENT (mA)

6.4

6.2

6.0
300 325 375350 400 425 450

+105°C

+125°C

+25°C

-40°C

RF FREQUENCY (MHz)

BIT-ERROR RATE

vs. AVERAGE INPUT POWER (FSK DATA

100

280kHz IF BW
FREQUENCY DEVIATION = ±50kHz

10

fRF = 434MHz

DEEP-SLEEP CURRENT

vs. TEMPERATURE

TEMPERATURE (°C)

SENSITIVITY

vs. TEMPERATURE (ASK DATA)

280kHz IF BW

0.2% BER

+85°C

MAX1471 toc02

12

10

8

6

4

DEEP-SLEEP CURRENT (µA)

2

0

-40 10-15 35 60 85 110

-102

-105

-108

MAX1471 toc03

1

0.2% BER

BIT-ERROR RATE (%)

0.1

0.01

-123 -121 -119 -117 -115 -113

fRF = 315MHz

AVERAGE INPUT POWER (dBm

SENSITIVITY

vs. TEMPERATURE (FSK DATA)

-102
280kHz IF BW

0.2% BER
FREQUENCY DEVIATION = ±50kHz

-104

-106

-108

SENSITIVITY (dBm)

-110

-112

-40 10-15 35 60 85 110

fRF = 434MHz

fRF = 315MHz

-1

1

BIT-ERROR RATE

0.2% BER

0.1

0.01

-115 -110-113 -108 -1

fRF = 315MHz

AVERAGE INPUT POWER (dBm

SENSITIVITY vs. FREQUENCY

DEVIATION (FSK DATA)

-98
280kHz IF BW

0.2% BER

-100

-102

-104

-106

SENSITIVITY (dBm)

-108

-110

-112
1101

-111

-114

SENSITIVITY (dBm)

-117

-120

-40 10-15 35 60 85 110

fRF = 434MHz

fRF = 315MHz

TEMPERATURE

RSSI vs. RF INPUT POWER

1.6
AGC HYSTERESIS: 3dB

1.4

HIGH-GAIN MODE

1.2

1.0

0.8

RSSI (V)

0.6

0.4

0.2

LOW-GAIN MODE

0

-130 -90 -70-110

-50

AGC SWITCH
POINT

-30 -10 1

MAX1471

315MHz/434MHz Low-Power, 3V/5V
ASK/FSK Superheterodyne Receiver

6 _______________________________________________________________________________________

B

Typical Operating Characteristics (continued)

(

Typical Application Circuit

, V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434MHz, TA= +25°C, unless otherwise noted.)

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 -50-70 -30 -10 10
RF INPUT POWER (dBm)

IMAGE REJECTION

vs. TEMPERATURE

48

46

44

42

IMAGE REJECTION (dB)

40

38

-40 10-15 35 60 85 110

fRF = 434MHz

DELTA

MAX1471 toc10

RSSI

fRF = 315MHz

°

3.5

2.5

1.5

0.5

-0.5

-1.5

-2.5

-3.5

MAX1471 toc13

FSK DEMODULATOR OUTPUT

vs. IF FREQUENCY

2.0

1.6

1.2

DELTA (%)

0.8

0.4

FSK DEMODULATOR OUTPUT (V)

0

10.4 10.5 10.710.6 10.8 10.9 11.0
IF FREQUENCY (MHz)

NORMALIZED IF GAIN

vs. IF FREQUENCY

5

0

-5

-10

NORMALIZED IF GAIN (dBm)

-15

-20
1 10 100

IF FREQUENCY (MHz)

SYSTEM VOLTAGE GAIN

vs. IF FREQUENCY

60

50

MAX1471 toc11

40

30

20

SYSTEM GAIN (dB)

10

0

-10
010155 202530

45dB IMAGE
REJECTION

IF FREQUENCY (MHz)

UPPER SIDEBAND

LOWER SIDEBAND

S11 LOG-MAGNITUDE PLOT WITH

MATCHING NETWORK OF RFIN (434MHz)

10dB/

MAX1471 toc14

div

0dB

434MHz

-16.4dB

START: 50MHz STOP: 1GHz

FROM RFIN
TO MIXOUT

= 434MHz

f

RF

MAX1471 toc12

MAX1471 toc15

0d

S11 SMITH CHART OF RFIN (434MHz)

500MHz

MAX1471 toc16

200MHz

MAX1471

315MHz/434MHz Low-Power, 3V/5V

ASK/FSK Superheterodyne Receiver

_______________________________________________________________________________________

7

Typical Operating Characteristics (continued)

(

Typical Application Circuit

, V

AVDD

= V

DVDD

= V

HVIN

= +3.0V, fRF= 434MHz, TA= +25°C, unless otherwise noted.)

Pin Description

INPUT IMPEDANCE vs. INDUCTIVE

DEGENERATION

90

fRF = 315MHz

80

L1 = 0nH

70

60

IMAGINARY IMPEDANCE

50

40

30

REAL IMPEDANCE (Ω)

20

10

0

REAL IMPEDANCE

1 100

INDUCTIVE DEGENERATION (nH)

10

PHASE NOISE vs. OFFSET FREQUENCY

-50
fRF = 315MHz

-60

-70

-80

-90

PHASE NOISE (dBc/Hz)

-100

MAX1471 toc17

-125

-150

-175

-200

-225

-250

-275

-300

-325

-350

MAX1471 toc19

INPUT IMPEDANCE vs. INDUCTIVE

90

DEGENERATION

fRF = 434MHz

80

L1 = 0nH

70

60

50

40

30

IMAGINARY IMPEDANCE (Ω)

REAL IMPEDANCE (Ω)

20

10

IMAGINARY
IMPEDANCE

REAL IMPEDANCE

0

1 100

INDUCTIVE DEGENERATION (nH)

10

MAX1471 toc18

-125

-150

-175

-200

-225

-250

-275

-300

-325

-350

IMAGINARY IMPEDANCE (Ω)

PHASE NOISE vs. OFFSET FREQUENCY

-50
fRF = 434MHz

-60

-70

-80

-90

PHASE NOISE (dBc/Hz)

-100

MAX1471 toc20

-110

-120
100 1k 1M 10M

10k 100k

OFFSET FREQUENCY (Hz)

-110

-120
100 1k 1M 10M

10k 100k

OFFSET FREQUENCY (Hz)

PIN NAME FUNCTION

1 DSA- Inverting Data Slicer Input for ASK Data

2 DSA+ Noninverting Data Slicer Input for ASK Data

3 OPA+ Noninverting Op-Amp Input for the ASK Sallen-Key Data Filter

4 DFA Data-Filter Feedback Node. Input for the feedback of the ASK Sallen-Key data filter.

5 XTAL2 2nd Crystal Input

MAX1471

315MHz/434MHz Low-Power, 3V/5V
ASK/FSK Superheterodyne Receiver

8 _______________________________________________________________________________________

Pin Description (continued)

PIN NAME FUNCTION

6 XTAL1 1st Crystal Input

7 AVDD

8 LNAIN Low-Noise Amplifier Input

9 LNASRC

10 LNAOUT Low-Noise Amplifier Output. Connect to mixer through an LC tank filter.

11 MIXIN+ Differential Mixer Input. Must be AC-coupled to driving input.

12 MIXIN- Differential Mixer Input. Bypass to AGND with a capacitor.
13 MIXOUT 330Ω Mixer Output. Connect to the input of the 10.7MHz IF filter.

14 AGND Analog Ground
15 IFIN- Differential 330Ω IF Limiter Amplifier Input. Bypass to AGND with a capacitor.
16 IFIN+ Differential 330Ω IF Limiter Amplifier Input. Connect to output of the 10.7MHz IF filter.

17 PDMINF

18 PDMAXF

19 DSF- Inverting Data Slicer Input for FSK Data

20 DSF+ Noninverting Data Slicer Input for FSK Data

21 OPF+ Noninverting Op-Amp Input for the FSK Sallen-Key Data Filter

22 DFF Data-Filter Feedback Node. Input for the feedback of the FSK Sallen-Key data filter.

23 DGND Digital Ground

24 DVDD

25 FDATA Digital Baseband FSK Demodulator Data Output
26 CS Active-Low Chip-Select Input

27 DIO Serial Data Input/Output

28 SCLK Serial Interface Clock Input

29 HVIN High-Voltage Supply Input. For 3V operation, connect HVIN to AVDD and DVDD.

30 ADATA Digital Baseband ASK Demod Data Output

31 PDMINA

32 PDMAXA

— EP Exposed Pad. Connect to ground.

Analog Power-Supply Voltage for RF Sections. AVDD is connected to an on-chip +3.0V low-dropout
regulator. Decouple to AGND with a 0.1µF capacitor.

Low-Noise Amplifier Source for External Inductive Degeneration. Connect an inductor to AGND to set
LNA input impedance.

Minimum-Level Peak Detector for FSK Data. Connect to ground if peak detector is not used. See the
Peak Detectors section.

Maximum-Level Peak Detector for FSK Data. Connect to ground if peak detector is not used. See the
Peak Detectors section.

Digital Power-Supply Voltage for Digital Sections. Connect to AVDD. Decouple to DGND with a 10nF
capacitor.

Minimum-Level Peak Detector for ASK Output. Connect to ground if peak detector is not used. See the
Peak Detectors section.

Maximum-Level Peak Detector for ASK Output. Connect to ground if peak detector is not used. See the
Peak Detectors section.