LMX2354TM/NOPB

Clock Generators, PLLs, Frequency Synthesizers Overview

The LMX2354 is a PLLatinum Fractional N/Integer N dual low power frequency synthesizer designed for local oscillator subsystems in radio transceivers. Fabricated using TI's 0.5 µm BiCMOS process, it operates from 2.7V to 5.5V with typical current consumption of 7 mA at 3V. The device features quadruple modulus prescalers (16/17/20/21 or 8/9/12/13) and modulo 15 or 16 fractional compensation circuitry. It supports continuous divide ratios of 80 to 32767 in the 1.2 GHz–2.5 GHz range and 40 to 16383 in the 550 MHz–1.2 GHz range. Programmable charge pump currents range from 100 µA to 1.6 mA.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Enhanced low noise fractional engine with programmable modulo 15 or 16 fractional RF N divider support.
• Dual independent phase-locked loops with separate RF and IF sections for flexible system architecture.
• Programmable charge pump output current levels adjustable in 100 µA steps up to 1.6 mA.
• Digital filtered lock detect function integrated within each phase detector loop.

Clock Generators, PLLs, Frequency Synthesizers Applications

• Portable wireless communications systems including PCS and PCN
• Dual mode cellular telephone systems
• Zero blind slot TDMA systems
• Spread spectrum communication systems such as CDMA
• Cable TV tuners

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify component authenticity through authorized distribution channels. Confirm package type matches design requirements, as the device is available in both 24-pin TSSOP and 24-pin LGA configurations. Ensure handling procedures account for ESD sensitivity ratings below 2kV during storage and assembly.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select this component when designing dual-loop frequency synthesis architectures requiring low power consumption. Evaluate the specific prescaler configuration needed based on target operating frequencies between 550 MHz and 2.5 GHz. Consider the availability of internal voltage doubler functionality if operating near the lower supply voltage limits.

Clock Generators, PLLs, Frequency Synthesizers Part Context

The LMX2354 belongs to the PLLatinum family of frequency synthesizers manufactured by Texas Instruments. It serves as an enhanced successor to earlier models like the LMX2350, offering improved fractional compensation capabilities and broader prescaler options. The device is specifically engineered to meet the stringent phase noise and switching speed requirements of modern mobile communication standards.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

The datasheet identifies the LMX2354 as pin compatible and functionally equivalent to the LMX2350. When replacing an LMX2350, note that the unused prescaler bit location shifts due to different A counter widths. Verify register programming adjustments are made to accommodate these architectural differences.