LMX2353TM/NOPB

Clock Generators, PLLs, Frequency Synthesizers Overview

The LMX2353TM/NOPB is a PLLatinum fractional N single frequency synthesizer designed for local oscillator subsystems. It operates with an RF input range of 0.5 GHz to 2.5 GHz and supports an oscillator input frequency up to 50 MHz. The device functions on a supply voltage between 2.7 V and 5.5 V, consuming typically 5.5 mA at 3.0 V. It features a programmable charge pump with output currents ranging from 100 µA to 1.6 mA in 100 µA steps. The component utilizes a 16/17 or 32/33 dual modulus prescaler and includes modulo 15 or 16 fractional compensation circuitry within the N divider.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Fractional N synthesis capability using modulo 15 or 16 compensation circuitry for precise tuning resolution
• Programmable charge pump current levels adjustable from 100 µA to 1.6 mA via serial interface
• Integrated FastLock mode functionality utilizing uncommitted CMOS outputs for rapid loop bandwidth adjustment
• Digital filtered lock detect output providing status indication of phase-locked condition

Clock Generators, PLLs, Frequency Synthesizers Applications

• Portable wireless communications systems including PCS and PCN
• Zero blind slot TDMA cellular and cordless telephone systems
• Spread spectrum communication systems such as CDMA
• Cable TV tuners (CATV) requiring stable local oscillator signals

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify that the ordering suffix /NOPB confirms lead-free compliance and absence of specific hazardous substances per RoHS directives. Confirm the package designation matches the required surface mount footprint, specifically the 16-pin TSSOP configuration. Ensure the revision level aligns with the design requirements for the target application environment.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select this component when a low power fractional N synthesizer is required for frequencies up to 2.5 GHz. Consider the available prescaler options: use the 16/17 ratio for the 0.5 GHz to 1.2 GHz range and the 32/33 ratio for 1.2 GHz to 2.5 GHz. Evaluate the need for the FastLock feature if rapid frequency switching is critical to the system performance.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This device belongs to the PLLatinum family of frequency synthesizers developed by National Semiconductor, now part of Texas Instruments. It is engineered using a 0.5µ ABiC V silicon BiCMOS process technology. The LMX2353 serves as a single-channel solution intended to replace older integer-N synthesizers where finer frequency resolution and lower phase noise are necessary for modern radio transceiver architectures.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation.