LMX2352TM/NOPB

Clock Generators, PLLs, Frequency Synthesizers Overview

The LMX2352TM/NOPB is a dual low power frequency synthesizer featuring an Integer N IF PLL and a Fractional N RF PLL. It operates on a single supply voltage ranging from 2.7 V to 5.5 V, with typical current consumption of 4.75 mA at 3.0 V. The device supports an RF operating frequency up to 1.2 GHz using selectable 8/9 or 16/17 prescalers, while the IF section covers frequencies up to 550 MHz with an 8/9 prescaler. It includes a programmable charge pump with output currents adjustable from 100 µA to 1.6 mA in 100 µA steps for the RF loop and fixed levels for the IF loop. Configuration is managed via a three-wire MICROWIRE serial interface.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Dual independent phase-locked loops combining fractional N synthesis for the RF path and integer N synthesis for the IF path.
• Integrated fractional compensation circuitry utilizing modulo 15 or 16 division to minimize spurious signals without external current injection.
• Programmable charge pump architecture allowing precise tuning of output current magnitude to optimize loop filter performance.
• Flexible reference oscillator input block supporting both external clock sources and internal crystal oscillator configurations.

Clock Generators, PLLs, Frequency Synthesizers Applications

• Portable wireless communication systems including PCS and cordless telephones
• Dual mode cellular telephone transceiver local oscillators
• Zero blind slot TDMA system implementations
• Spread spectrum communication systems such as CDMA
• Cable TV tuners requiring stable frequency generation

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify that the ordering suffix matches the specific package requirement, as the LMX2352 family is available in both 24-pin TSSOP and 24-pin CSP surface mount plastic packages. Confirm the component is lead-free compliant if RoHS standards are mandatory for the assembly process. Ensure the supplier provides traceability documentation consistent with National Semiconductor (Texas Instruments) manufacturing records.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select the LMX2352 over the LMX2350 when the application requires an RF frequency range limited to 1.2 GHz, as this variant offers lower power consumption and optimized prescaler ratios for sub-GHz operation. Evaluate the required charge pump current against the VCO control sensitivity to determine the appropriate CP_WORD settings. Consider the availability of the specific package type, either TSSOP or CSP, based on board space constraints and thermal management requirements.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This component belongs to the LMX2350/LMX2352 PLLatinum family of monolithic integrated frequency synthesizers. Manufactured using a 0.5µ ABiC V silicon BiCMOS process, the series is designed for local oscillator subsystems in radio transceivers. The LMX2352 specifically targets applications requiring RF frequencies up to 1.2 GHz, distinguishing it from the higher-frequency LMX2350 which extends to 2.5 GHz.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

The LMX2350TM/NOPB serves as a functional substitute within the same family, offering identical pinouts and programming interfaces but supporting a higher maximum RF frequency of 2.5 GHz. Verify that the increased power consumption and different prescaler options of the LMX2350 do not impact the specific design constraints of the target application.