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参数资料
| 型号： | LMX2331LMDA |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | PLL合成/DDS/VCOs |
| 英文描述： | PLL FREQUENCY SYNTHESIZER, 2000 MHz, UUC |
| 封装： | DIE |
| 文件页数： | 11/30页 |
| 文件大小： | 578K |
| 代理商： | LMX2331LMDA |
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Application Information (Continued)
between 1X and 4X values. This is accomplished by increas-
ing the charge pump output current from 1 mA in the stan-
dard mode to 4 mA in Fastlock.
FASTLOCK CIRCUIT IMPLEMENTATION
A diagram of the Fastlock scheme as implemented in Na-
tional Semiconductors LMX233XL PLL is shown in
Figure 5.
When a new frequency is loaded, and the RF Icp
o bit is set
high the charge pump circuit receives an input to deliver 4
times the normal current per unit phase error while an open
drain NMOS on chip device switches in a second R2 resistor
element to ground. The user calculates the loop filter compo-
nent values for the normal steady state considerations. The
device configuration ensures that as long as a second iden-
tical damping resistor is wired in appropriately, the loop will
lock faster without any additional stability considerations to
account for. Once locked on the correct frequency, the user
can return the PLL to standard low noise operation by send-
ing a MICROWIRE instruction with the RF Icp
o bit set low.
This transition does not affect the charge on the loop filter
capacitors and is enacted synchronous with the charge
pump output. This creates a nearly seamless change be-
tween Fastlock and standard mode.
DS012806-17
FIGURE 4. Open Loop Response Bode Plot
DS012806-18
FIGURE 5. Fastlock PLL Architecture
www.national.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LMX2331LSLB | 制造商:NSC 制造商全称:National Semiconductor 功能描述:PLLatinum⑩ Low Power Dual Frequency Synthesizer for RF Personal Communications |
| LMX2331LSLBX | 制造商:Texas Instruments 功能描述: |
| LMX2331LSLBX/NOPB | 功能描述:IC FREQ SYNTH DUAL 24-LCSP RoHS:是 类别:集成电路 (IC) >> 时钟/计时 - 时钟发生器，PLL，频率合成器 系列:PLLatinum™ 标准包装:39 系列:- 类型:* PLL:带旁路 输入:时钟 输出:时钟 电路数:1 比率 - 输入:输出:1:10 差分 - 输入:输出:是/是 频率 - 最大:170MHz 除法器/乘法器:无/无 电源电压:2.375 V ~ 3.465 V 工作温度:0°C ~ 70°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| LMX2331LSLDX | 制造商:NSC 制造商全称:National Semiconductor 功能描述:PLLatinumTM Low Power Dual Frequency Synthesizer for RF Personal Communications |
| LMX2331LSLDX/NOPB | 功能描述:IC FREQ SYNTH DUAL RF COMM 20CSP RoHS:是 类别:集成电路 (IC) >> 时钟/计时 - 时钟发生器，PLL，频率合成器 系列:PLLatinum™ 标准包装:39 系列:- 类型:* PLL:带旁路 输入:时钟 输出:时钟 电路数:1 比率 - 输入:输出:1:10 差分 - 输入:输出:是/是 频率 - 最大:170MHz 除法器/乘法器:无/无 电源电压:2.375 V ~ 3.465 V 工作温度:0°C ~ 70°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
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