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參數(shù)資料
| 型號(hào)： | LTC6990IDCB#TRMPBF |
| 廠商： | Linear Technology |
| 文件頁數(shù)： | 8/30頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC OSC SILICON 1MHZ 6DFN |
| 產(chǎn)品培訓(xùn)模塊： | TimerBlox Family Timing Devices |
| 特色產(chǎn)品： | TimerBlox? |
| 標(biāo)準(zhǔn)包裝： | 500 |
| 系列： | TimerBlox® |
| 類型： | 振蕩器 - 硅 |
| 頻率： | 488Hz ~ 1MHz |
| 電源電壓： | 2.25 V ~ 5.5 V |
| 電流 - 電源： | 235µA |
| 工作溫度： | -40°C ~ 85°C |
| 封裝/外殼： | 6-WFDFN 裸露焊盤 |
| 包裝： | 帶卷 (TR) |
| 供應(yīng)商設(shè)備封裝： | 6-DFN-EP（2x3） |
| 安裝類型： | 表面貼裝 |
| 配用： | DC1562A-A-ND - BOARD EVAL LTC6990 |
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LTC6990
16
6990fc
For more information www.linear.com/LTC6990
APPLICATIONS INFORMATION
Frequency Modulated Operation (Voltage-Controlled
Oscillator)
Operating the LTC6990 as a voltage-controlled oscillator in
its simplest form is achieved with one additional resistor.
As shown in Figure 11, voltage VCTRL sources/sinks a cur-
rent through RVCO to vary the ISET current, which in turn
modulatestheoutputfrequencyasdescribedinEquation(2).
fOUT =
1MHz 50k
NDIV RVCO
1
+
RVCO
RSET
VCTRL
VSET
(2)
fOUT, choose a value for NDIV that meets the following
conditions
62.5kHz
fOUT(MIN)
≤ NDIV ≤
1MHz
fOUT(MAX)
(3a)
The 16:1 frequency range of the master oscillator and
the 2:1 divider step-size provides several overlapping fre-
quency spans to guarantee that any 8:1 modulation range
can be covered by a single NDIV setting. RVCO allows the
gain to be tailored to the application, mapping the VCTRL
voltage range to the modulation range.
Step 2: Calculate KVCO and f(0V)
KVCO and f(0V) define the VCO’s transfer function and sim-
plify the calculation of the the RVCO and RSET resistors.
Calculate these parameters using the following equations.
KVCO =
fOUT(MAX) fOUT(MIN)
VCTRL(MAX) VCTRL(MIN)
(3b)
f(0V) = fOUT(MAX) + KVCO VCTRL(MIN)
(3c)
KVCO and f(0V) are not device settings or resistor values
themselves. However, beyond their utility for the resistor
calculations,theseparametersprovideausefulandintuitive
way to look at the VCO application. The f(0V) parameter is
the output frequency when VCTRL is at 0V. Viewed another
way, it is the fixed output frequency when the RVCO and
RSETresistorsareinparallel.KVCOisactuallythefrequency
gain of the circuit.
With KVCO and f(0V) determined, the RVCO and RSET values
can now be calculated.
Step 3: Calculate and Select RVCO
The next step is to calculate the correct value for RVCO
using the following equation.
RVCO =
1MHz 50k
NDIV VSET KVCO
(3d)
Select the standard resistor value closest to the calculated
value.
Figure 11. Voltage Controlled Oscillator
6990 F08
LTC6990
OE
GND
SET
OUT
V+
DIV
C1
0.1F
R1
R2
RSET
V+
RVCO
VCTRL
Equation (2) can be re-written as shown below, where
f(0V) is the output frequency when VCTRL = 0V, and KVCO
is the frequency gain. Note that the gain is negative (the
output frequency decreases as VCTRL increases).
fOUT = f(0V)– KVCO VCTRL
f(0V) =
1MHz 50k
NDIV RSET RVCO
(
)
KVCO =
1MHz 50k
NDIV VSET RVCO
The design procedure for a VCO is a simple four step
process. First select the NDIV value. Then calculate the
intermediate values KVCO and f(0V). Next, calculate and
select the RVCO resistor. Finally calculate and select the
RSET resistor.
Step 1: Select the NDIV Frequency Divider Value
For best accuracy, the master oscillator frequency should
fall between 62.5kHz and 1MHz. Since fMASTER = NDIV
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| LTC6990IDCBTRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:TimerBlox: Voltage Controlled Silicon Oscillator |
| LTC6990IDCB-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:TimerBlox: Voltage Controlled Silicon Oscillator |
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| LTC6990IS6#TRMPBF | 功能描述:IC OSC SILICON 1MHZ TSOT23-6 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:TimerBlox® 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 |
| LTC6990IS6#TRPBF | 功能描述:IC OSC SILICON 1MHZ TSOT23-6 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:TimerBlox® 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 |
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