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参数资料
| 型号： | LMX2312USLDX |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | XO, clock |
| 英文描述： | PLLatinum⑩ Ultra Low Power Frequency Synthesizer for RF Personal Communications |
| 中文描述： | PLL FREQUENCY SYNTHESIZER, 1200 MHz, QCC20 |
| 封装： | THIN, CSP-20 |
| 文件页数： | 24/29页 |
| 文件大小： | 662K |
| 代理商： | LMX2312USLDX |
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1.0 Functional Description
(Continued)
20043805
1.9 Fastlock
OUTPUT
The FL pin can be used as the Fastlock output. The FL pin
can also be programmed as constant low, constant high
(referenced to V
CC
), or constant high impedance, selectable
through the T register. When the device is configured in
Fastlock mode, the charge pump current can be increased
4x while maintaining loop stability by synchronously switch-
ing a parallel loop filter resistor to ground with the FL pin,
resulting in a
～
2x increase in loop bandwidth. The loop
bandwidth, the zero gain crossover point of the open loop
gain, is effectively shifted up in frequency by a factor of the
square root of 4 = 2 during Fastlock mode. For
ω
' = 2
ω
, the
phase margin during Fastlock also will remain constant. The
user calculates the loop filter component values for the
normal steady state considerations. The device configura-
tion ensures that as long as a second resistor, equal to the
primary resistor value, is wired in appropriately, the loop will
lock faster without any additional stability considerations.
The PLL can be configured to be in either the Fastlock mode
continuously or in the Fastlock mode that uses a timeout
counter to switch it back to the normal mode. In the Fastlock
mode the charge pump current is set to 4 mA and the FL pin
is set low. If the user sets the PLL to be in the Fastlock mode
continuously he can send the R register with CPo_4X set low
(R[18] = 0) and sets TO_CNTR[11:0] to 1. The user can set
the PLL to normal mode (1 mA mode and set the FL pin to
TRI-STATE mode) by programming TO_CNTR[11:0] to 0. If
the user elects to use the timeout counter, he can program
the timeout counter from 4 to 4095. The timeout counter will
count down the programmed number of phase detector ref-
erence cycles. After the programmed number of phase de-
tector reference cycles is reached, it will automatically set
the charge pump current to the 1 mA mode and set the FL
pin to TRI-STATE mode. A complete programming descrip-
tion is in Section 3.4.2.
L
www.national.com
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相关代理商/技术参数 |
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|---|---|
| LMX2312USLDX/NOPB | 功能描述:IC FREQ SYNTH 1.2GHZ 20LAMTCSP 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:* |
| LMX2313U | 制造商:NSC 制造商全称:National Semiconductor 功能描述:PLLatinum⑩ Ultra Low Power Frequency Synthesizer for RF Personal Communications |
| LMX2313USLDX | 制造商:NSC 制造商全称:National Semiconductor 功能描述:PLLatinum⑩ Ultra Low Power Frequency Synthesizer for RF Personal Communications |
| LMX2313USLDX/NOPB | 功能描述:IC FREQ SYNTH 600MHZ 20LAMTCSP RoHS:否 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:* |
| LMX2314 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:1.2 GHz Frequency Synthesizer for RF Personal Communications |
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