LMX2485Q-Q1 Datasheet, PDF (1/50 Pages) Texas Instruments – Low Power Dual PLLatinum Frequency Synthesizers

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LMX2485Q-Q1
SNOSCP7A – MARCH 2013 – REVISED JANUARY 2016
LMX2485Q-Q1 500 MHz - 3.1 GHz High Performance Delta-Sigma Low Power Dual
PLLatinum™ Frequency Synthesizers With 800-MHz Integer PLL
1 Features
•1 Quadruple Modulus Prescaler for Lower Divides
– RF PLL: 8/9/12/13 or 16/17/20/21
– IF PLL: 8/9 or 16/17
• Advanced Delta Sigma Fractional Compensation
– 12-Bit or 22-Bit Selectable Fractional Modulus
– Up to 4th Order Programmable Delta-Sigma
Modulator
• Improved Lock Times and Programming
– Fastlock / Cycle Slip Reduction Requiring Only
a Single-Word Write
– Integrated Time-Out Counter
• Wide Operating Range
– LMX2485Q-Q1 RF PLL: 500 MHz to 3.1 GHz
• Useful Features
– Digital Lock Detect Output
– Hardware and Software Power-Down Control
– On-Chip Input Frequency Doubler
– RF Phase Detector Frequency Up to 50 MHz
– 2.5-V to 3.6-V Operation With I_CC = 5.0 mA
– LMX2485Q-Q1 is AEC-Q100 Grade 2
Qualified and is Manufactured on an
Automotive Grade Flow
3 Description
The LMX2485Q-Q1 is a low power, high performance
delta-sigma fractional-N PLL with an auxiliary integer-
N PLL. The device is fabricated using TI’s advanced
process.
With delta-sigma architecture, fractional spurs at
lower offset frequencies are pushed to higher
frequencies outside the loop bandwidth. The ability to
push close in spur and phase noise energy to higher
frequencies is a direct function of the modulator
order. Unlike analog compensation, the digital
feedback technique used in the LMX2485Q-Q1 is
highly resistant to changes in temperature and
variations in wafer processing. The LMX2485Q-Q1
delta-sigma modulator is programmable up to fourth
order, which allows the designer to select the
optimum modulator order to fit the phase noise, spur,
and lock time requirements of the system.
Serial data for programming the LMX2485Q-Q1 is
transferred through a three-line, high-speed (20-MHz)
MICROWIRE interface. The LMX2485Q-Q1 offers
fine frequency resolution, low spurs, fast
programming speed, and a single word write to
change the frequency. This makes it ideal for direct
digital modulation applications, where the N-counter
is directly modulated with information. The
LMX2485Q-Q1 is available in a 24-lead 4.0 × 4.0 ×
0.8 mm WQFN package.
2 Applications
• Cellular Phones and Base Stations
• Direct Digital Modulation Applications
• Satellite and Cable TV Tuners
• WLAN Standards
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMX2485Q-Q1
WQFN (24)
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Functional Block Diagram
FinIF
ENOSC
OSCin
OSCout
VddRF1
VddRF2
VddRF3
VddRF4
VddRF5
FinRF
FinRF*
CE
CLK
DATA
LE
1X / 2X
IF N Divider
8/9
or
16/17
Prescaler
B Counter
A Counter
IF R
Divider
RF R
Divider
RF N Divider
8/9/12/13
C Counter
or
16/17/2R0/F2N1
DividBerCounter
Prescaler
A Counter
MICROWIRE
Interface
6'
Compensation
Phase
Comp
IF
LD
RF LD
Phase
Comp
Charge
Pump
Ftest/LD
MUX
Charge
Pump
RF Fastlock
VddIF1
VddIF2
CPoutIF
Ftest/LD
CPoutRF
FLoutRF
GND
GND
GND
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.