LMX2485Q-Q1 Automotive Delta-Sigma Low Power Dual PLL for RF Personal Communications | TI.com

LMX2485Q-Q1 (ACTIVE) Automotive Delta-Sigma Low Power Dual PLL for RF Personal Communications

 

Recommended alternative parts

  • LMX2485  -  3.0 GHz Maximum Operating Frequency

Description

The LMX2485Q-Q1 is a low power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. The device is fabricated using TI’s advanced process.

With delta-sigma architecture, fractional spurs at lower offset frequencies are pushed to higher frequencies outside the loop bandwidth. The ability to push close in spur and phase noise energy to higher frequencies is a direct function of the modulator order. Unlike analog compensation, the digital feedback technique used in the LMX2485Q-Q1 is highly resistant to changes in temperature and variations in wafer processing. The LMX2485Q-Q1 delta-sigma modulator is programmable up to fourth order, which allows the designer to select the optimum modulator order to fit the phase noise, spur, and lock time requirements of the system.

Serial data for programming the LMX2485Q-Q1 is transferred through a three-line, high-speed (20-MHz) MICROWIRE interface. The LMX2485Q-Q1 offers fine frequency resolution, low spurs, fast programming speed, and a single word write to change the frequency. This makes it ideal for direct digital modulation applications, where the N-counter is directly modulated with information. The LMX2485Q-Q1 is available in a 24-lead 4.0 × 4.0 × 0.8 mm WQFN package.

Features

  • Quadruple Modulus Prescaler for Lower Divides
    • RF PLL: 8/9/12/13 or 16/17/20/21
    • IF PLL: 8/9 or 16/17
  • Advanced Delta Sigma Fractional Compensation
    • 12-Bit or 22-Bit Selectable Fractional Modulus
    • Up to 4th Order Programmable Delta-Sigma
      Modulator
  • Improved Lock Times and Programming
    • Fastlock / Cycle Slip Reduction Requiring Only
      a Single-Word Write
    • Integrated Time-Out Counter
  • Wide Operating Range
    • LMX2485Q-Q1 RF PLL: 500 MHz to 3.1 GHz
  • Useful Features
    • Digital Lock Detect Output
    • Hardware and Software Power-Down Control
    • On-Chip Input Frequency Doubler
    • RF Phase Detector Frequency Up to 50 MHz
    • 2.5-V to 3.6-V Operation With ICC = 5.0 mA
    • LMX2485Q-Q1 is AEC-Q100 Grade 2
      Qualified and is Manufactured on an
      Automotive Grade Flow

Parametrics

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Part number Order Output frequency (Min) (MHz) Output frequency (Max) (MHz) Normalized PLL phase noise (dBc/Hz) 1/f noise (10-kHz offset at 1-GHz carrier) (dBc/Hz) Current consumption (mA) VCC (V) Integrated VCO
LMX2485Q-Q1 Order now 500     3100     -210     -104     5     2.5 to 3.6     No    
LMX2485E Order now 50     3000     -210     -104     3.3     2.5 to 3.6     No    
LMX2486 Samples not available 1000     4500     -210     -104     5.7     2.5 to 3.6     No    
LMX2487 Samples not available 1000     6000     -210     -104     5.7     2.5 to 3.6     No    
LMX2487E Samples not available 3000     7500     -210     -104     5.7     2.5 to 3.6     No    
LMX2492-Q1 Order now 500     14000     -227     -120     60     3.15 to 3.45     No