LMX2571_16 Datasheet, PDF (1/62 Pages) Texas Instruments – LMX2571 Low-Power, High-Performance PLLatinum™ RF Synthesizer

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LMX2571
SNAS654A – MARCH 2015 – REVISED JULY 2016
LMX2571 Low-Power, High-Performance PLLatinum™ RF Synthesizer
with FSK Modulation
1 Features
•1 Any Frequency from 10 MHz to 1344 MHz
• Low Phase Noise and Spurs
– –123 dBc/Hz at 12.5 kHz Offset at 480 MHz
– –145 dBc/Hz at 1 MHz Offset at 480 MHz
– Normalized PLL Noise Floor of –231 dBc/Hz
– Spurious Better Than –75 dBc/Hz
• New FastLock to Reduce Lock Time
• A Novel Technique to Remove Integer Boundary
Spurs
• Integrated 5-V Charge Pump and Output Divider
for External VCO Operation
• 2-, 4- and 8-Level or Arbitrary Level Direct Digital
FSK Modulation
• One TX/RX Output or Two Fanout Outputs
• Crystal, XO or Differential Reference Clock Input
• Low Current Consumption
– 39-mA Typical Synthesizer Mode (Internal
VCO)
– 9-mA Typical PLL Mode (External VCO)
• 24-Bit Fractional-N Delta Sigma Modulator
2 Applications
• Duplex Mode Digital Professional 2-Way Radio
– dPMR, DMR, PDT, P25 Phase I
• Low Power Radio Communication Systems
– Satcom Modem
– Wireless Microphone
– Propriety Wireless Connectivity
• Handheld Test and Measurement Equipment
3 Description
The LMX2571 is a low-power, high-performance,
wideband PLLatinum™ RF synthesizer that
integrates a delta-sigma fractional N PLL, multiple
core voltage-controlled oscillator (VCO),
programmable output dividers and two output buffers.
The VCO cores work up to 5.376 GHz resulting in
continuous output frequency range of 10 MHz to
1344 MHz.
This synthesizer can also be used with an external
VCO. To that end, a dedicated 5-V charge pump and
an output divider are available for this configuration.
A unique programmable multiplier is also
incorporated to help improve spurs, allowing the
system to use every channel even if it falls on an
integer boundary.
The output has an integrated SPDT switch that can
be used as a transmit/receive switch in FDD radio
application. Both outputs can also be turned on to
provide 2 outputs at the same time.
The LMX2571 supports direct digital FSK modulation
through programming or pins. Discrete level FSK,
pulse shaping FSK, and analog FM modulation are
supported.
A new FastLock technique can be used allowing the
user to step from one frequency to the next in less
than 1.5 ms even when an external VCO is used with
a narrow band loop filter.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMX2571
WQFN (36)
6.00 mm × 6.00 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic
3.3V 3.3V/5V
0.1µF 0.1µF
Vcc3p3
5V CP
CP Int. charge
VccIO
supply MUX pump
XO
R-divider
Phase
detector
Output
divider
Prescaler
LMX2571
OP
MUX
100pF
To driver amplifier
0.1µF
VrefVCO
2.2µF _VregVCO
µWIRE
N-divider
G4
Fast 5V charge VCO
modulator lock pump MUX
Output
divider
Lock
dect
Enable
100pF
To receive mixer
FLout CPoutExt
Fin
SPI
FSK
SoC / DSP
MUXout CE TrCtl
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.