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參數(shù)資料
| 型號： | LMX2372MDC |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | PLL合成/DDS/VCOs |
| 英文描述： | PLL FREQUENCY SYNTHESIZER, 1200 MHz, UUC |
| 封裝： | DIE |
| 文件頁數(shù)： | 8/27頁 |
| 文件大小： | 550K |
| 代理商： | LMX2372MDC |
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2.0 Programming Description (Continued)
2.3.5 PLL Prescaler Select (P_Aux, P_Main)
The LMX2370, LMX2371 and LMX2372 contain two dual modulus prescalers. A 32/33 or a 16/17 prescaler can be selected for
the 2.5 GHz and 2.0 GHz RF synthesizers in the LMX2370 and LMX2371 respectively. The 16/17 prescaler is only rated for input
frequencies below 1.2 GHz. A 16/17 or an 8/9 prescaler can be selected for the both 1.2 GHz synthesizers on the LMX2372 as
well as the 1.2 GHz synthesizers on the LMX2370 and LMX2371. The 8/9 prescaler is only rated for input frequencies below
550 MHz.
Prescaler Value
P_Main, (Main_N18) or
P_Aux (Aux_N18)
2.5 GHz PLL
2.0 GHz PLL
1.2 GHz PLL
0
16/17
8/9
1
32/33
16/17
Allowable Prescaler Values
PLL Input Frequency
2.5 GHz PLL
2.0 GHz PLL
1.2 GHz PLL
f
IN > 1.2 GHz
32/33
NA
550 < f
IN < 1200 MHz
16/17 or 32/33
16/17
f
IN < 550 MHz
16/17 or 32/33
8/9 or 16/17
2.3.5.1 Pulse Swallow Function
f
VCO = [(P xB)+ A]xfOSC/R
f
VCO:
Output frequency of external voltage controlled oscillator (VCO)
B:
Preset divide ratio of binary 13-bit programmable counter (3 to 8191)
A:
Preset divide ratio of binary 5-bit swallow counter
0
≤ A ≤ 31 {P=32}
0
≤ A ≤ 15 {P=16}
0
≤ A ≤ 7 {P=8}
A
≤ B
f
OSC:
Output frequency of the external reference frequency oscillator
R:
Preset divide ratio of binary 15-bit programmable reference counter (3 to 32767)
P:
Preset modulus of dual modulus prescaler (P = 8, 16, or 32)
2.3.6 PLL Power Down Control (Aux_PWDN, Main_PWDN)
The Aux_PWDN (Aux_N19) and Main_PWDN (Main_N19) bits are used to power down either the Main or Auxiliary PLL’s charge
pump portion, or the entire PLL block depending on the setting of the respective charge pump TRI-STATE bit (Aux_CP
o_TRI or
Main_CP
o_TRI) in the R_CNTR register. The power-down mechanism is described below. The R and N counters for each respec-
tive PLL are disabled and held at reset during the synchronous and asynchronous power down modes. This will allow a smooth
acquisition of the Main RF signal when the oscillator input buffer is still active (Auxiliary loop powered up) and vice versa. Upon
powering up, both R and N counters will start at the “zero” state, and the relationship between R and N will not be random.
Synchronous Power Down Mode
One of the PLL loops can be synchronously powered down by first setting the respective loop’s TRI-STATE mode bit LOW (R17
= 0) and then asserting its power down mode bit (N19 = 1). The power down function is gated by the charge pump. Once the
power down program bits Aux_PWDN (Aux_N19) and Main_PWDN (Main_N19) and TRI-STATE bits Aux_CP
o_TRI (Aux_R17)
or Main_CP
o_TRI (Main_R17) are loaded, the part will go into power down mode upon the completion of a charge pump pulse
event.
Asynchronous Power Down Mode
One of the PLL loops can be asynchronously powered down by first setting the respective loop’s TRI-STATE mode bit HI (R17
= 1) and then asserting its power down mode bit (N19 = 1). The power down function is NOT gated by the charge pump. Once
the power down program bits Aux_PWDN (Aux_N19) and Main_PWDN (Main_N19) and its respective TRI-STATE bit Aux_CP
o-
_TRI (Aux_R17) or Main_CP
o_TRI (Main_R17) are loaded, the part will go into power down mode immediately.
LMX2370/LMX2371/LMX2372
www.national.com
16
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| LMX2372SLBX | 功能描述:IC FREQ SYNTH DUAL 24LAMINATECSP RoHS:否 類別:集成電路 (IC) >> 時鐘/計時 - 時鐘發(fā)生器，PLL，頻率合成器 系列:PLLatinum™ 標(biāo)準(zhǔn)包裝:39 系列:- 類型:* PLL:帶旁路 輸入:時鐘 輸出:時鐘 電路數(shù):1 比率 - 輸入:輸出:1:10 差分 - 輸入:輸出:是/是 頻率 - 最大:170MHz 除法器/乘法器:無/無 電源電壓:2.375 V ~ 3.465 V 工作溫度:0°C ~ 70°C 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:* |
| LMX2372TM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:PLLatinum⑩ Dual Frequency Synthesizer for RF Personal Communications |
| LMX2372TMX | 功能描述:IC FREQ SYNTH DUAL 20-TSSOP RoHS:是 類別:集成電路 (IC) >> 時鐘/計時 - 時鐘發(fā)生器，PLL，頻率合成器 系列:PLLatinum™ 標(biāo)準(zhǔn)包裝:39 系列:- 類型:* PLL:帶旁路 輸入:時鐘 輸出:時鐘 電路數(shù):1 比率 - 輸入:輸出:1:10 差分 - 輸入:輸出:是/是 頻率 - 最大:170MHz 除法器/乘法器:無/無 電源電壓:2.375 V ~ 3.465 V 工作溫度:0°C ~ 70°C 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:* |
| LMX2377U | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:PLLatinum⑩ Ultra Low Power Dual Frequency Synthesizer for RF Personal Communications |
| LMX2377U WAF | 制造商:Texas Instruments 功能描述: |
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