Datasheet > LMX2485_0610

LMX2485_0610

更新时间： 2024-11-21 03:54:15

品牌	Logo	应用领域
美国国家半导体 - NSC		半导体
页数	文件大小	规格书
37页	881K
描述
50 MHz - 3.0 GHz High Performance Delta-Sigma Low Power Dual PLLatinum⑩ Frequency Synthesizers with 800 MHz Integer PLL

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LMX2485_0610 数据手册

October 2006

LMX2485/LMX2485E

50 MHz - 3.0 GHz High Performance Delta-Sigma Low

™

Power Dual PLLatinum Frequency Synthesizers with

800 MHz Integer PLL

n Direct digital modulation applications

General Description

n Satellite and cable TV tuners

The LMX2485 is a low power, high performance delta-sigma

n WLAN Standards

fractional-N PLL with an auxiliary integer-N PLL. The device

is fabricated using National Semiconductor’s advanced pro-

cess.

Features

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 LMX2485 is highly resistant

to changes in temperature and variations in wafer process-

ing. The LMX2485 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.

Quadruple Modulus Prescalers for Lower Divide Ratios

n RF PLL: 8/9/12/13 or 16/17/20/21

n IF PLL: 8/9 or 16/17

Advanced Delta Sigma Fractional Compensation

n 12 bit or 22 bit selectable fractional modulus

n Up to 4th order programmable delta-sigma modulator

Features for Improved Lock Times and Programming

n Fastlock / Cycle slip reduction

n Integrated time-out counter

n Single word write to change frequencies with Fastlock

Serial data for programming the LMX2485 is transferred via

a three line high speed (20 MHz) MICROWIRE interface.

The LMX2485 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 modula-

tion applications, where the N counter is directly modulated

with information. The LMX2485 is available in a 24 lead

4.0 X 4.0 X 0.8 mm LLP package.

Wide Operating Range

n LMX2485 RF PLL: 500 MHz to 3.0 GHz

n LMX2485E RF PLL: 50 MHz to 3.0 GHz

Useful Features

n Digital lock detect output

n Hardware and software power-down control

n On-chip crystal reference frequency doubler.

n RF phase comparison frequency up to 50 MHz

n 2.5 to 3.6 volt operation with I_CC= 5.0 mA at 3.0 V

Applications

n Cellular phones and base stations

CDMA, WCDMA, GSM/GPRS, TDMA, EDGE, PDC

Functional Block Diagram

20087701

™

PLLatinum is a trademark of National Semiconductor Corporation.

DS200877

www.national.com

12 3 4 5 6 7...37

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与LMX2485_0610相关器件

型号	品牌	获取价格	描述	数据表
LMX2485_08	NSC	获取价格	50 MHz - 3.0 GHz High Performance Delta-Sigma
LMX2485E	NSC	获取价格	50 MHz - 3.0 GHz High Performance Delta-Sigma
LMX2485E	TI	获取价格	用于射频个人通信的 50MHz 至 3GHz Δ-Σ 低功耗双路 PLL
LMX2485ESQ	NSC	获取价格	50 MHz - 3.0 GHz High Performance Delta-Sigma
LMX2485ESQ/NOPB	NSC	获取价格	IC PLL FREQUENCY SYNTHESIZER, 3000 MHz, PQCC24, 4 X 4 MM, 0.8 MM, PLASTIC, LLP-24, PLL or
LMX2485ESQ/NOPB	TI	获取价格	用于射频个人通信的 50MHz 至 3GHz Δ-Σ 低功耗双路 PLL \| RTW \|
LMX2485ESQX	NSC	获取价格	50 MHz - 3.0 GHz High Performance Delta-Sigma
LMX2485ESQX/NOPB	TI	获取价格	用于射频个人通信的 50MHz 至 3GHz Δ-Σ 低功耗双路 PLL \| RTW \|
LMX2485Q-Q1	TI	获取价格	500MHz 至 3GHz 汽车类 Δ-Σ 低功耗双路 PLL
LMX2485QSQ/NOPB	TI	获取价格	500MHz 至 3GHz 汽车类 Δ-Σ 低功耗双路 PLL \| RTW \| 24 \|

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