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参数资料
| 型号： | MK3724GLFT |
| 厂商： | INTEGRATED DEVICE TECHNOLOGY INC |
| 元件分类： | 时钟产生/分配 |
| 英文描述： | 73.728 MHz, OTHER CLOCK GENERATOR, PDSO16 |
| 封装： | 4.40 MM, 0.65 MM PITCH, LEAD FREE, TSSOP-16 |
| 文件页数： | 4/8页 |
| 文件大小： | 156K |
| 代理商： | MK3724GLFT |
VCXO PLUS AUDIO CLOCK FOR STB
MDS 3724 C
4
Revision 121904
In te gr ated Circuit Systems ● 525 Ra ce Street, San Jose, CA 9512 6 ● tel (4 08) 297-1 201 ● www.icst.com
MK3724
External Component Selection
The MK3724 requires a minimum number of external
components for proper operation.
Decoupling Capacitors
Decoupling capacitors of 0.01
F should be connected
between VDD and GND on pins 3 and 4, pins 6 and 7,
and pins 11 and 14 as close to the MK3724 as
possible. For optimum device performance, the
decoupling capacitors should be mounted on the
component side of the PCB. Avoid the use of vias in the
decoupling circuit.
Series Termination Resistor
When the PCB traces between the clock outputs and
the loads are over 1 inch, series termination should be
used. To series terminate a 50
trace (a commonly
used trace impedance), place a 33
resistor in series
with the clock line, as close to the clock output pin as
possible. The nominal impedance of the clock output is
20
.
Quartz Crystal
The MK3724 VCXO function consists of the external
crystal and the integrated VCXO oscillator circuit. To
assure the best system performance (frequency pull
range) and reliability, a crystal device meeting ICS’
recommended parameters must be used, and the
layout guidelines discussed in the following section
must be followed.
See Application Note MAN05 for a full list of crystal
parameters.
The frequency of oscillation of a quartz crystal is
determined by its “cut” and by the load capacitors
connected to it. The MK3724 incorporates on-chip
variable load capacitors that “pull” (change) the
frequency of the crystal. The crystal specified for use
with the MK3724 is designed to have zero frequency
error when the total of on-chip + stray capacitance is 14
pF.
The external crystal must be connected as close to the
chip as possible and should be on the same side of the
PCB as the MK3724. There should be no via’s between
the crystal pins and the X1 and X2 device pins. There
should be no signal traces underneath or close to the
crystal.
Crystal Tuning Load Capacitors
The crystal traces should include pads for small fixed
capacitors, one between X1 and ground, and another
between X2 and ground. Stuffing of these capacitors
on the PCB is optional. The need for these capacitors is
determined at system prototype evaluation, and is
influenced by the particular crystal used (manufacture
and frequency) and by PCB layout. The typical required
capacitor value is 1 to 4 pF.
To determine the need for and value of the crystal
adjustment capacitors, you will need a PC board of
your final layout, a frequency counter capable of about
1 ppm resolution and accuracy, two power supplies,
and samples of the crystals which you plan to use in
production. You will also need measured initial
accuracy for each crystal at the specified crystal load
capacitance (CL).
To determine the value of the crystal capacitors:
1. Connect VDD to 3.3 V. Connect pin 5 to the second
power supply. Adjust the voltage on pin 5 to 0V.
Measure and record the frequency of the CLK output.
2. Adjust the voltage on pin 5 to 3.3 V. Measure and
record the frequency of the same output.
To calculate the centering error:
Where:
ftarget = nominal crystal frequency
errorxtal =actual initial accuracy (in ppm) of the crystal
being measured
If the centering error is less than ±25 ppm, no
adjustment is needed. If the centering error is more
than 25 ppm negative, the PC board has excessive
stray capacitance and a new PCB layout should be
considered to reduce stray capacitance. (Alternately,
the crystal may be re-specified to a higher load
capacitance. Contact ICS for details.) If the centering
error is more than 25 ppm positive, add identical fixed
centering capacitors from each crystal pin to ground.
The value for each of these caps (in pF) is given by:
Error
10
6
x
f3.3 3.0
()V
f
tet
arg
–
()
f
0V
f
tet
arg
–
()
+
f
tet
arg
----------------------------------------------------------------------------------------
error
xtal
–
=
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MK3724GLFTR | 功能描述:时钟合成器/抖动清除器 RoHS:否 制造商:Skyworks Solutions, Inc. 输出端数量: 输出电平: 最大输出频率: 输入电平: 最大输入频率:6.1 GHz 电源电压-最大:3.3 V 电源电压-最小:2.7 V 封装 / 箱体:TSSOP-28 封装:Reel |
| MK3724GTR | 功能描述:IC VCXO DTV/SET-TOP 16-TSSOP 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:- 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:* |
| MK3724IL | 制造商:ICS 制造商全称:ICS 功能描述:VCXO PLUS AUDIO CLOCK FOR STB |
| MK3725 | 制造商:ICS 制造商全称:ICS 功能描述:DUAL OUTPUT 3.3 VOLT VCXO |
| MK3725S | 制造商:ICS 制造商全称:ICS 功能描述:DUAL OUTPUT 3.3 VOLT VCXO |
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