Texas Instruments LMX2571EVM

Overview

The LMX2571EVM from Texas Instruments is an evaluation module designed to validate the operation and RF performance of the LMX2571 wideband fractional-N frequency synthesizer (QFN36 package), supporting VCO output frequencies from 4300 MHz to 5376 MHz with integrated loop filter components, Spur-B-Gone™ technology, and FSK modulation capability - used in radar, wireless infrastructure, and test equipment development.

For engineers reviewing the LMX2571EVM datasheet, LMX2571EVM setup, LMX2571EVM software interface, or LMX2571EVM phase noise measurements, this page provides verified board-level specifications, measured performance data (including default-mode phase noise down to –155 dBc/Hz at 100 kHz offset), USB2ANY-based programming workflow, and hardware configuration options for reference clock, power supply, and RF output routing.

Technical Context

The LMX2571EVM implements a complete evaluation platform for the LMX2571 IC, featuring on-board 20 MHz crystal oscillator (CWX813-020.0M), dual regulated power supplies (LP5900SD-3.3/NOPB and LP38798SD-ADJ/NOPB), SMA connectors for RFoutRx/RFoutTx, OSCin, Fin, and Vcc inputs, and configurable loop filter components (R2LFA = 680 Ω, C1LFA = 390 pF, C2LFA = 4.7 nF) enabling 204.8 kHz loop bandwidth at 4.8 GHz VCO frequency.

Board-level design includes FR4 4-layer stack-up with dedicated ground plane isolation for OSCin signal integrity, top-layer-only component placement, T-pad/T-splitter RF output options via TS5A21366DCUR analog switch, and uWire header (52601-S10-8LF) for direct register-level access - all documented in SNAU176A User's Guide (June 2015 revision).

Key Specifications

Availability

LMX2571EVM is available at Aetrix Electronics and suitable for RF system validation, synthesizer characterization, and high-frequency PLL design requiring stable component supply, traceable sourcing, and full documentation support.

Supply support for LMX2571EVM includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions across industrial, automotive, and communications markets.

The LMX2571EVM belongs to TI's high-performance clock and timing evaluation platform family, engineered specifically to accelerate RF synthesizer prototyping, phase noise benchmarking, and loop filter optimization for wireless infrastructure and defense applications.

FAQ

What is the primary function of the LMX2571EVM?

The LMX2571EVM is a Texas Instruments evaluation module built to characterize the LMX2571 wideband fractional-N frequency synthesizer. It provides immediate access to RF outputs (RFoutRx/RFoutTx), programmable reference inputs (OSCin/OSCin*), and loop filter tuning - enabling engineers to measure phase noise, verify lock detection, evaluate Spur-B-Gone™ performance, and validate FSK modulation behavior without custom PCB design. The LMX2571EVM includes all necessary regulators, clock sources, and interface hardware per SNAU176A.

Which software is required to operate the LMX2571EVM?

The LMX2571EVM requires TI's CodeLoader software (downloaded from ti.com/tool/codeloader) for configuration and control. It communicates via USB2ANY interface (HPA665-001) connected to the uWire header. The software supports default mode loading, register-level bit manipulation, port setup (USB or parallel), and real-time device programming - though readback functionality is limited in current versions and may require external tools. All operational guidance is documented in the LMX2571EVM User's Guide (SNAU176A).

Can the LMX2571EVM be powered from a 5V source?

Yes - the LMX2571EVM supports three power configurations: (1) apply 5V to Vcc5V SMA connector and use onboard LP38798 regulator to generate 3.3V for Vcc3p3; (2) apply 3.3V directly to Vcc3p3 SMA; or (3) apply >5V to Vcc5V_TB and regulate down using U4. The board includes jumpers (R39/R39b) and dual LDOs (U3: LP5900SD-3.3/NOPB; U4: LP38798SD-ADJ/NOPB) to ensure clean, low-noise supply rails essential for synthesizer performance. Current draw exceeds 100 mA at 3.3V.

Does the LMX2571EVM include a built-in crystal oscillator?

Yes - the LMX2571EVM integrates a 20 MHz CWX813-020.0M crystal oscillator (Y1) with on-board enable circuitry (R1/R3 jumper configuration). While functional for quick startup, its phase noise is not optimized for ultra-low-jitter applications; the User's Guide recommends bypassing it for critical measurements and using a cleaner external reference. Burn-in (several hours of operation) may improve stability and phase noise performance.

How is lock detection implemented on the LMX2571EVM?

The LMX2571EVM uses the LMX2571's internal lock detect output routed to a green LED (D1), but TI explicitly states this LED is unreliable - it may fail to illuminate even when locked, and physical pressure can intermittently restore function. For accurate verification, engineers must monitor current consumption during power-down sequences or implement external lock detection via the LMX2571's dedicated LOCK pin (Pin 17 on U1), as confirmed in Section 1.5 of SNAU176A. The LMX2571EVM does not provide alternative lock status signaling.