MAX2745ECM ,Single-Chip Global Positioning System Receiver Front-Endfeatures a voltage booster, which can Power Consumption as Low as 41mW at 2.4Vextend the power-sup ..
MAX2745ECM ,Single-Chip Global Positioning System Receiver Front-EndBlock Diagram/In-Vehicle Navigation Systems (IVNSs)Pin ConfigurationLocation-Based Services (PDAs a ..
MAX274ACNG ,4th- and 8th-Order Contnuous-Time Active FiltersELECTRICAL CHARACTERISTICS (continued) -1.1. MAX274
(V+ I':::,?: 5V, V- 'CCC' -5V, test circuit ..
MAX274ACNG+ ,4th- and 8th-Order, Continuous-Time Active FiltersELECTRICAL CHARACTERISTICS -rMAX274
(V+ = 5V, V- = -5V, test circuit A of Figure la, TA = TMIN t ..
MAX274ACWI ,4th- and 8th-Order Contnuous-Time Active FiltersGeneral Description
The MAX274 and MAX275 are continuous-time active
filters consisting of inde ..
MAX274AENG ,8th-order continuous-time active filterELECTRICAL CHARACTERISTICS (continued) -1.1. MAX274
(V+ I':::,?: 5V, V- 'CCC' -5V, test circuit ..
MAX6045BEUR-T ,Precision / Low-Power / Low-Dropout /MAX6012/6021/6025/6030/6041/6045/605019-4777; Rev 2; 10/99Precision, Low-Power, Low-Dropout, SOT23- ..
MAX604CPA ,5V/3.3V or Adjustable, Low-Dropout, Low IQ, 500mA Linear RegulatorsApplicationsMAX604EPA -40°C to +85°C 8 Plastic DIP5V and 3.3V RegulatorsMAX604ESA -40°C to +85°C 8 ..
MAX604CPA ,5V/3.3V or Adjustable, Low-Dropout, Low IQ, 500mA Linear RegulatorsGeneral Description ________
MAX604CSA ,5V/3.3V or Adjustable, Low-Dropout, Low IQ, 500mA Linear RegulatorsMAX603/MAX60419-0269; Rev 0; 9/945V/3.3V or Adjustable, Low-Dropout, Low I , 500mA Linear Regulator ..
MAX604CSA+ ,5V/3.3V or Adjustable, Low-Dropout, Low-IQ, 500mA Linear RegulatorsMAX603/MAX60419-0269; Rev 0; 9/945V/3.3V or Adjustable, Low-Dropout, Low I , 500mA Linear Regulator ..
MAX604CSA+T ,5V/3.3V or Adjustable, Low-Dropout, Low-IQ, 500mA Linear RegulatorsFeatures' 500mA Output Current, with Foldback CurrentThe MAX603/MAX604 low-dropout, low quiescent c ..
MAX2745ECM
Single-Chip Global Positioning System Receiver Front-End
General DescriptionThe MAX2745 complete single-chip global positioning
system (GPS) RF front-end downconverter utilizes many
innovative and leading-edge RF CMOS design tech-
niques. 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 pro-
vides 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 tem-
perature 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.
ApplicationsIn-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
FeaturesComplete Single-Chip GPS Radio for 16.368MHz
and 32.736MHz FloorplansSingle-Ended or Differential Outputs at 4.092MHzLow 3.5dB Typical Noise FigureNo External IF SAW or Discrete Filters RequiredOn-Chip Temperature Sensor2.4V to 3.6V Operational Supply Voltage RangePower Consumption as Low as 41mW at 2.4VWide -40°C to +85°C Operational Temperature
Range
MAX2745
Receiver Front-End
Ordering Information*EP = Exposed paddle.
Block Diagram/
Pin Configuration
Typical Operating Circuit appears at end of data sheet
MAX2745
Single-Chip Global Positioning System
Receiver Front-End
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 (VDD+ 0.3V)
RF LNA Input Power.......................................................+10dBm
Continuous Power Dissipation (TA= +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
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.)
MAX2745
Single-Chip Global Positioning System
Receiver Front-End
Note 1:At TA= +25°C, min/max limits are guaranteed by production test.
Note 2:At TA= -40°C, min/max limits are guaranteed by design and characterization.
Note 3:At TA= +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,
Typical Operating Characteristics(MAX2745 EV kit, VDD= +3.0V, SHDN = GND, fRF= 1575.42MHz, and TA= +25°C, unless otherwise noted.)
MAX2745
Single-Chip Global Positioning System
Receiver Front-End
Pin Description
Typical Operating Characteristics (continued)(MAX2745 EV kit, VDD= +3.0V, SHDN = GND, fRF= 1575.42MHz, and TA= +25°C, unless otherwise noted.)
MAX2745
Single-Chip Global Positioning System
Receiver Front-End
Pin Description (continued)
Functional Diagram
MAX2745
Single-Chip Global Positioning System
Receiver Front-End
Detailed DescriptionThe MAX2745 complete single-chip GPS front-end
downconverter utilizes many innovative and leading-
edge RF CMOS design techniques. This high-perfor-
mance, 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 LNA/mixer, IF section, digital sampler,
and local oscillator synthesizer. The MAX2745 also pro-
vides voltage supply for an external LNA. In addition,
the MAX2745 features a voltage booster that 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
design in 16MHz, as well as a TCXO implementation. In
addition, the MAX2745 incorporates an on-chip tempera-
ture sensor and crystal oscillator with trimmed capaci-
tors, resulting in a very accurate frequency and
additional system cost savings.
The MAX2745 also incorporates a 2MHz bandwidth
bandpass filter to reduce off-band noise. The band-
width and the center frequency of the bandpass filter
are guaranteed by an advanced tuning scheme.
The MAX2745 is offered in a space-saving 48-pin TQFP
package. The operational temperature range is speci-
fied from -40°C to +85°C. The power consumption of
this device is as low as 41mW at 2.4V.
LNA/MixerThe RF input signal from the GPS antenna is fed
through an LNA with a gain of 20dB. The amplified sig-
nal is then fed to a mixer that downconverts the signal
(1575.42MHz) to a quadrature differential IF of
4.092MHz.
IF StageThe quadrature IF signals pass through the IF filter,
which rejects the out-of-band spurs by more than 60dB
and the image noise by 17dB (typ). After the image
reject filter, the signal is converted from quadrature to
differential. The filtered IF signal is then amplified by
the AGC block, which sets the VGA output signal level
to a predetermined value through the application using
56dB of dynamic range.
IF Output SelectionThe sampled outputs of the GPS signal are available in
a single-ended or limited-differential format. The ODS
pin controls the output format.
SynthesizerAn on-chip VCO provides quadrature differential LO
signals to the downconverting mixer. An on-chip crystal
oscillator driver generates the reference frequency. The
integrated synthesizer includes the VCO, crystal oscil-
lator driver, main frequency divider, phase-frequency
detector, and charge pump. It uses an off-chip PLL
loop filter and crystal. If a TCXO is used, connect the
output of the TCXO to XTALIN.
The main division ratio for the synthesizer is 96 or 48.
With this division ratio, a low-side injection LO can be
used with a 16.368MHz or 32.736MHz crystal. Note that
if a 3rd overtone crystal is used for the 32.736MHz, an
off-chip notch filter to reject the fundamental frequency
is required. The notch filter can be built with one induc-
tor and one capacitor.
Control BlockThis block is used mainly for testing purposes and to
set the internal trimmed capacitor. This block is pro-
grammed through the VSport.
VSport Serial Data InterfaceThe serial interface within the MAX2745 is used by the
baseband to communicate control signals and is also
used for internal testing of the device. (This serial port
is described in a separate document, which is available
upon request.)
Trimmed VCXO FrequencyAn on-chip, trimmed capacitor with a temperature coeffi-
cient of better than 30ppm/°C is used to compensate for
the component variation of the reference frequency
associated circuitry. The value of the capacitor is pro-
grammed in 512 binary steps and ranges from a mini-
mum of80fFto a maximum of 40pF, ±20%. Pro-
gramming is accomplished with the VSport serial inter-
face. The no load capacitance on the crystal out follows
the equation:
C(no load) = ([Register Value] x 40/512) pF
Upon power-up, the capacitor value is set to the mini-
mum value. This enables the MAX2745 to work with an
off-chip, trimmed capacitor. If the baseband has the
capability of programming the radio, the off-chip,
trimmed capacitor can be omitted by setting the inter-
nal trimmed capacitor through the VSPORT.
