LMX2350TMX/NOPB

Clock Generators, PLLs, Frequency Synthesizers Overview

The LMX2350TMX/NOPB is a dual low power frequency synthesizer from the PLLatinum family, featuring a fractional N RF loop and an integer N IF loop. It operates on a single supply voltage ranging from 2.7 V to 5.5 V with typical current consumption of 6.75 mA for the LMX2350 variant at 3.0 V. The device supports RF input frequencies up to 2.5 GHz (LMX2350) or 1.2 GHz (LMX2352) and IF frequencies up to 550 MHz. It utilizes a MICROWIRE serial interface for configuration and includes programmable charge pump currents from 100 µA to 1.6 mA.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Dual-modulus prescalers support fractional N synthesis in the RF path and integer division in the IF path.
• Programmable charge pump output current levels allow optimization of loop filter performance.
• Integrated digital filtered lock detect function provides status indication.
• MICROWIRE serial interface enables flexible control of internal registers.

Clock Generators, PLLs, Frequency Synthesizers Applications

• Portable wireless communications systems
• Dual mode cellular telephone systems
• Zero blind slot TDMA systems
• Spread spectrum communication systems

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify that the ordering suffix 'TMX' corresponds to the TSSOP-24 surface mount package as specified in the datasheet. Confirm the specific model variant (LMX2350 vs LMX2352) matches the required RF frequency range. Ensure the component meets RoHS standards indicated by the NOPB suffix. Cross-reference the manufacturer part number with official Texas Instruments documentation to confirm availability and revision status.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select the LMX2350 variant if the application requires an RF operating range extending up to 2.5 GHz. Choose the LMX2352 variant for applications requiring RF frequencies up to 1.2 GHz. Consider the available prescaler ratios (16/17 or 32/33 for LMX2350; 8/9 or 16/17 for LMX2352) when designing the feedback divider network. Ensure the external VCO input sensitivity aligns with the device's specified input requirements.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This component belongs to the PLLatinum family of frequency synthesizers designed for local oscillator subsystems in radio transceivers. It is fabricated using a silicon BiCMOS process. The device integrates dual modulus prescalers and fractional compensation circuitry to generate stable low-noise control signals for external voltage controlled oscillators.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

The LMX2352 serves as a lower-frequency alternative within the same family. Verify pin compatibility and register programming sequences before substituting variants. Check if the target application requires the higher maximum RF frequency supported by the LMX2350.

Clock Generators, PLLs, Frequency Synthesizers FAQ

What are the available prescaler ratios for the LMX2350?

The LMX2350 supports 16/17 or 32/33 prescale ratios for the RF divider and an 8/9 prescaler for the IF divider.

How is the charge pump current configured?

The RF charge pump current is programmable from 100 µA to 1.6 mA in 100 µA steps via the MICROWIRE interface. The IF charge pump can be set to 100 µA or 800 µA.

What is the function of the Fo/LD pin?

The Fo/LD pin is a multifunction output that can provide analog or digital lock detect signals, or output the state of the internal R or N counters based on programming.