MAXIM MAX2745 Technical data

General Description

The MAX2745 complete single-chip global positioning
system (GPS) RF front-end downconverter utilizes many
innovative and leading-edge RF CMOS design tech­niques. This high-performance, state-of-the-art device
consumes extremely low power and eliminates the
need for costly SAW and bulky discrete IF filters. The
MAX2745 incorporates a fully integrated low-noise
amplifier (LNA) and mixer, IF section, digital sampler,
and local oscillator synthesizer. The MAX2745 also pro­vides a voltage supply for an external LNA. In addition,
the MAX2745 features a voltage booster, which can
extend the power-supply voltage to as low as 1.6V.

The MAX2745 supports both 3rd overtone crystal
designs in 32MHz and fundamental frequency crystal
designs in 16MHz, as well as a TCXO implementation.
In addition, the MAX2745 incorporates an on-chip tem­perature sensor and crystal oscillator with trimmed
capacitors, resulting in a very accurate frequency and
additional system cost savings.

The MAX2745 is available in a space-saving 48-pin
TQFP package and is specified for the extended (-40°C
to +85°C) temperature range. The power consumption
of this device is as low as 41mW at 2.4V.

Applications

In-Vehicle Navigation Systems (IVNSs)

Location-Based Services (PDAs and
Accessories)

Telematics (Vehicle/Asset Tracking and
Inventory Management)

Recreational Handheld/Walkie Talkies

Geographical Information Systems (GISs)

Emergency Roadside Assistance

Emergency Response Systems

Digital Cameras/Camcorders

Consumer Electronics

Features

♦ Complete Single-Chip GPS Radio for 16.368MHz

and 32.736MHz Floorplans

♦ Single-Ended or Differential Outputs at 4.092MHz

♦ Low 3.5dB Typical Noise Figure

♦ No External IF SAW or Discrete Filters Required

♦ On-Chip Temperature Sensor

♦ 2.4V to 3.6V Operational Supply Voltage Range

♦ Power Consumption as Low as 41mW at 2.4V

♦ Wide -40°C to +85°C Operational Temperature

Range

MAX2745

Single-Chip Global Positioning System

Receiver Front-End

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3425; Rev 0; 10/04

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-PACKAGE

MAX2745ECM -40°C to +85°C 48 TQFP-EP*

*EP = Exposed paddle.

Block Diagram/

Pin Configuration

VCXO

BIAS

LNA/MIXER

PFD

DIVIDER

CHG

PUMP

VCO

TEMPERATURE

SENSOR

VSPORT

BANDPASS FILTER

FILTER AUTOMATIC TUNING

AGC

QUANTIZER

VOLTAGE
BOOSTER

48

XTALIN

11

V

DD

12

AGC_FIL

25

V

DD

10

IEXT_LNA

7

RFIN

9

V

DD

47

XTALOUT

2

CBIAS

4

30

GND

27

V

DD

20

CKOUT

19

VDD_VB

1

RBIAS

3

V

DD

V

DD

5

GND

13

V

DD

14

GND

15

XTAL_SSEL

16

XTAL_CSEL

17

BST_CTRL

18

TEST_EN

21

DOUT

23

VB_CS-

24

V

OUT

22

VB_CS+

28

VOUT-

29

VOUT+

31

SCLK

32

V

DD

33

COE

34

CFS

35

ODS

36

BPF_CTRL

37

SDATA

38

V

TO

39

V

DD

40

VTUNE

41

GND

42

CP_OUT

43

V

DD

44

GND

46

V

DD

6

GND

8

GND

GND

26

45

SHDN

MAX2745

Typical Operating Circuit appears at end of data sheet

MAX2745

Single-Chip Global Positioning System
Receiver Front-End

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(MAX2745 EV kit, VDD= +2.4V to +3.6V, SHDN = GND, TA= -40°C to +85°C. Typical values are at VDD= +3.0V and 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.

VDDto GND...........................................................-0.3V to +3.7V

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

DD

+ 0.3V)

RF LNA Input Power .......................................................+10dBm

Continuous Power Dissipation (T

A

= +70°C)

48-Pin TQFP-EP (derate 12.5mW/°C above +70°C) ............1W

Operating Temperature Range ...........................-40°C to +85°C

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

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

Soldering Temperature (10s) ...........................................+300°C

PARAMETER CONDITIONS

MIN

TYP

MAX

UNITS

Supply Voltage

3.6 V

VDD = +3.0V, TA = +25°C (Note 1)

27 mA

Supply Current

Shutdown mode 11 µA

Optional External LNA Supply
Current

V

DD

= +3.0V

mA

Logic-Input High Voltage

V

Logic-Input Low Voltage

V

Logic-Input Bias Current

µA

CAUTION! ESD SENSITIVE DEVICE

AC ELECTRICAL CHARACTERISTICS

(MAX2745 EV kit, VDD= +2.4V to +3.6V, SHDN = GND, TA= -40°C to +85°C. Typical values are at VDD= +3.0V and TA= +25°C,
unless otherwise noted.)

PARAMETER CONDITIONS

TYP

UNITS

GENERAL PERFORMANCE

Maximum Conversion Gain (Notes 2, 3) 105

dB

Input Frequency

MHz

Noise Figure Measured at quantizer output 3.5 dB
Return Loss (S11) -14 dB
LNA/Mixer Input IP3

-25

dBm

Output IF Frequency

MHz

OUTPUT STAGE

Differential (VOUT+, VOUT-), CL < 20pF 16

Output Rise/Fall Time

Single ended (DOUT), C

L

<20pF 6

ns

Differential

Output-Voltage-Level Low

Single ended 0

V

Differential

Output-Voltage-Level High

Single ended

V

DD

V

2.4

20.5

10

2.0

-10 +10

f1 = 5.09MHz and f2 = 7.09MHz above carrier frequency

MIN

1575.42

4.092

VDD - 0.9

0.5

MAX

120

MAX2745

Single-Chip Global Positioning System

Receiver Front-End

_______________________________________________________________________________________ 3

Note 1: At TA= +25°C, min/max limits are guaranteed by production test.
Note 2: At T

A

= -40°C, min/max limits are guaranteed by design and characterization.

Note 3: At T

A

= +25°C and +85°C, min/max limits are guaranteed by production test.

AC ELECTRICAL CHARACTERISTICS (continued)

(MAX2745 EV kit, VDD= +2.4V to +3.6V, SHDN = GND, TA= -40°C to +85°C. Typical values are at VDD= +3.0V and TA= +25°C,
unless otherwise noted.)

PARAMETER CONDITIONS

TYP

UNITS

SYNTHESIZER

Fundamental frequency crystal

Crystal Input Frequency

3rd overtone crystal

MHz

Charge-Pump Current 0.4 mA

f

OFFSET

= 10kHz offset,

BW

LOOP

= 70kHz

-81

Phase Noise

f

OFFSET

= 1MHz offset,

BW

LOOP

= 70kHz

dBc/Hz

Maximum PLL Spur BW

LOOP

= 70kHz -39 dBc

VCO Tuning Frequency Range (Notes 2, 3)

210 270

MHz

VCO Tuning Gain (Notes 2, 3)

210 310

MHz/V

IF STAGE

IF Stage Gain VGA set at maximum gain 80 dB
Dynamic Range IF Stage Gain 56 dB

Low-frequency corner 3.1

Bandpass Filter 1dB Corner
Frequency

High-frequency corner 5.1

MHz

Bandpass Filter 3dB Bandwidth 2.0

MHz

Bandpass Filter 60dB High-Side
Rejection

6.6

MHz

Bandpass Filter 60dB Low-Side
Rejection

1.6

MHz

Image Rejection 17 dB
In-Band Ripple 1dB
AGC Loop Lock Time 1ms

Typical Operating Characteristics

(MAX2745 EV kit, VDD= +3.0V, SHDN = GND, fRF= 1575.42MHz, and TA= +25°C, unless otherwise noted.)

SUPPLY CURRENT vs. TEMPERATURE

MAX2745 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

6040200-20

14

18

22

26

30

10

-40 80

VCC = 2.4V

VCC = 2.7V

VCC = 3V

LNA/MIXER GAIN vs. TEMPERATURE

MAX2745 toc02

TEMPERATURE (°C)

LNA MIXER GAIN (dB)

6040200-20

10

5

15

20

25

30

35

40

0

-40 80

VCC = 2.4V

VCC = 2.7V

VCC = 3V

IF STAGE GAIN vs. TEMPERATURE

MAX2745 toc03

TEMPERATURE (°C)

IF STAGE GAIN (dB)

6040200-20

70

65

75

80

85

90

95

100

60

-40 80

VCC = 2.4V

VCC = 2.7V

VCC = 3V

MIN

150
150

MAX

16.368

32.736

-104