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參數(shù)資料
| 型號(hào)： | LTC6902CMS |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | XO, clock |
| 英文描述： | Multiphase Oscillator with Spread Spectrum Frequency Modulation |
| 中文描述： | PLL FREQUENCY SYNTHESIZER, PDSO10 |
| 封裝： | PLASTIC, MSOP-10 |
| 文件頁數(shù)： | 6/16頁 |
| 文件大?。?/td> | 212K |
| 代理商： | LTC6902CMS |
LTC6902
6
6902f
QUICK DESIGU
Step 3. Calculating the R
SET
Resistor Value
The R
SET
resistor, the multiphase mode and the divider
setting set the output frequency (f
OUT
) for constant fre-
quency applications. For SSFM applications, the maxi-
mum frequency excursion (f
MAX
) is equal to f
OUT
.
R
k
MHz
V
N M f
=
=
=
0
N
Open
V
M
H
H
Open
V
0
SET
OUT
=
=
=
=
=
=
+
+
20
10
100
10
1
4
3
1
DIVPin
DIVPin
DIVPin
(4-Phase Output) PHPin
(3-Phase Output) P Pin
(2-Phase Output) P Pin
V
Step 4. Calculating the R
MOD
Resistor Value
(Note: For constant frequency applications R
MOD
is not
required. Disable SSFM by connecting the MOD pin to
GND)
R
SpreadingPercentage
R
MOD
SET
=
20
where the Spreading Percentage is defined by the
following:
SpreadingPercentage
f
f
f
MAX
MIN
MAX
=
100
–
where f
MAX
is the highest frequency excursion (set by the
R
SET
value calculated in Step 3) and f
MIN
is the lowest
frequency excursion.
Example
For a 4-phase, 250kHz clock with 40% spreading:
Connect PH Pin to V
+
→
Selects 4-Phase Mode, M = 4
Leave DIV Pin Open
→
N = 10
R
SET
= 20k
→
Sets f
OUT
= f
MAX
= 250kHz
R
MOD
= 10k
→
Sets Spreading to 40%
PIU
V
+
(Pin 1):
Supply Voltage ( 2.7V
≤
V
+
≤
5.5V). The supply
should be kept free from noise and ripple. It should be
bypassed directly to a ground plane with a 0.1
μ
F capacitor
placed as close to the pin as possible.
DIV (Pin 2):
Divider Setting Input. This three-state input
selects among three divider settings determining the value
of N in the frequency equation. Pin 2 should be tied to GND
for the
÷
1 setting, the highest frequency range. Floating
Pin 2, leaving it open, divides the master oscillator by 10.
Tie Pin 2 to V
+
for the
÷
100 setting, the lowest frequency
range. To detect a floating DIV pin, the LTC6902 places the
pin at the midsupply point with active circuitry. Therefore,
driving the DIV pin high requires sourcing approximately
2
μ
A. Similarly, driving the DIV pin low requires sinking
2
μ
A. When the DIV pin is floated, it should be bypassed by
a 1nF capacitor to GND or it should be surrounded by a
ground shield to prevent excessive coupling from other
PCB traces.
PH (Pin 3):
Phase Setting Input. This three-state input
selects among three multiphase options. This sets the
outputs to produce 2-phase, 3-phase or 4-phase signals.
It also sets the value of M in the frequency equation. Pin 3
should be tied to GND for the 2-phase setting. This is the
highest frequency range with M set to 1. Floating Pin 3,
leaving it open, selects the 3-phase setting. This also sets
M to 3. Tie Pin 3 to V
+
for the 4-phase setting. This is the
lowest frequency range as M is set to 4. To detect a floating
PH pin, the LTC6902 places the pin at the midsupply point
with active circuitry. Therefore, driving the PH pin high
requires sourcing approximately 2
μ
A. Similarly, driving
the PH pin low requires sinking 2
μ
A. When the PH pin is
floated, it should be bypassed by a 1nF capacitor to GND
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相關(guān)代理商/技術(shù)參數(shù) |
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| LTC6902CMS#PBF | 功能描述:IC OSC SILICON 20MHZ 10MSOP RoHS:是 類別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 可編程計(jì)時(shí)器和振蕩器 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 類型:振蕩器 - 晶體 計(jì)數(shù):- 頻率:- 電源電壓:2.3 V ~ 5.5 V 電流 - 電源:1.07mA 工作溫度:-30°C ~ 80°C 封裝/外殼:SOT-665 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:SS迷你型-5D 安裝類型:表面貼裝 其它名稱:AN8955SSMTXLTR |
| LTC6902CMS#PBF | 制造商:Linear Technology 功能描述:Programmable Oscillator IC |
| LTC6902CMS#TR | 功能描述:IC OSC SILICON 20MHZ 10MSOP RoHS:否 類別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 可編程計(jì)時(shí)器和振蕩器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:45 系列:- 類型:溫度 - 補(bǔ)償晶體振蕩器（TCXO） 計(jì)數(shù):- 頻率:25MHz 電源電壓:3.135 V ~ 3.465 V 電流 - 電源:1.5mA 工作溫度:-40°C ~ 85°C 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 包裝:管件 供應(yīng)商設(shè)備封裝:16-SOIC W 安裝類型:表面貼裝 |
| LTC6902CMS#TRPBF | 功能描述:IC OSC SILICON 20MHZ 10MSOP RoHS:是 類別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 可編程計(jì)時(shí)器和振蕩器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:45 系列:- 類型:溫度 - 補(bǔ)償晶體振蕩器（TCXO） 計(jì)數(shù):- 頻率:25MHz 電源電壓:3.135 V ~ 3.465 V 電流 - 電源:1.5mA 工作溫度:-40°C ~ 85°C 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 包裝:管件 供應(yīng)商設(shè)備封裝:16-SOIC W 安裝類型:表面貼裝 |
| LTC6902CMSPBF | 制造商:Linear Technology 功能描述:Programmable oscillator,5K-20MHz |
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