LMX2542 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – PLLatinum Cellular and GPS Frequency Synthesizer System with Integrated VCO

May 2004
LMX2542
PLLatinum^TM Cellular and GPS Frequency Synthesizer
System with Integrated VCO
General Description
LMX2542 is a highly integrated, high performance, low
power frequency synthesizer system optimized for Cellular-
CDMA 1xRTT and IS-95 mobile handsets and data systems
with GPS capabilities. Using a proprietary digital phase
locked loop technique, LMX2542 provides very stable, low
noise local oscillator (LO) signals for up and down conver-
sion in wireless communications devices.
LMX2542 includes a Voltage Controlled Oscillator (VCO) for
both the Cellular-CDMA and GPS frequency bands, a loop
filter, and a Fractional-N RF PLL based on a Delta Sigma
(∆Σ) modulator. In concert, these blocks form a closed loop
RF synthesizer system. The RF synthesizer system oper-
ates from 2087.73 MHz to 2155.14 MHz.
LMX2542 includes an Integer-N IF PLL also. For more flex-
ible loop filter designs, the IF PLL includes a 4-level pro-
grammable charge pump. Together with an external VCO
and loop filter, LMX2542 makes a complete closed loop IF
synthesizer system. The default IF frequency is 367.20 MHz.
Serial data is transferred to the device via a three-wire
MICROWIRE^TM interface (DATA, LE, CLK).
Operating supply voltage ranges from 2.7V to 3.3V.
LMX2542 features low current consumption: 22 mA at 2.8V.
LMX2542 is available in a 28-Pin Leadless Leadframe Pack-
age (LLP).
Features
n Small Size
5.0 mm x 5.0 mm x 0.75 mm 28-Pin LLP
n RF Synthesizer System
Integrated RF VCO
Integrated Loop Filter
Low Spurious, Low Phase Noise Fractional-N RF
PLL Based on 11-Bit ∆Σ modulator
5 kHz Frequency Resolution
Cellular-CDMA LO: 2105.28 MHz to 2155.14 MHz
(Requires an External LO /2 Circuit)
GPS LO: 2087.73 MHz
(Requires an External LO /1.5 Circuit)
n IF Synthesizer System
Integer-N IF PLL
Programmable Charge Pump Current Levels
IF LO: 367.20 MHz
n Supports Various Reference Oscillator Frequencies:
19.20 MHz/ 19.68 MHz
n Low Current Consumption:
22 mA typical at 2.8V
n 2.7V to 3.3V Operation
n RF Digital Filtered Lock Detect Output
n Hardware and Software Powerdown Control
Applications
n Cellular-CDMA 1xRTT and IS-95 Mobile Handsets with
GPS
n Cellular-CDMA 1xRTT and IS-95 Mobile Data Systems
with GPS
Leadless Leadframe Package (LQA28A)
20082411
PLLatinum™, MICROWIRE™ are trademarks of National Semiconductor Corporation.
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© 2004 National Semiconductor Corporation DS200824
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