参数资料
型号: ICS7151MI-50
元件分类: 时钟产生/分配
英文描述: 16.7 MHz, OTHER CLOCK GENERATOR, PDSO8
封装: 0.150 INCH, SOIC-8
文件页数: 3/8页
文件大小: 164K
代理商: ICS7151MI-50
Spread Spectrum Clock Generator
MDS 7151 E
3
Revision 012306
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126 tel (408) 297-1201 www.icst.com
ICS7151
External Components
The ICS7151 requires a minimum number of external
components for proper operation.
Decoupling Capacitor
A decoupling capacitor of 0.01F must be connected
between GND and VDD on pin 7, as close to this pin as
possible. For optimum device performance, the
decoupling capacitor should be mounted on the
component side of the PCB. Avoid the use of vias in the
decoupling circuit.
Series Termination Resistor
Series termination should be used on the clock output.
To series terminate a 50
trace (a commonly used
trace impedance) place a 27
resistor in series with
the clock line, as close to the clock output pin as
possible. The nominal impedance of the clock output is
25
.
PCB Layout Recommendations
For optimum device performance and lowest output
phase noise, the following guidelines should be
observed.
1) The 0.01F decoupling capacitor should be mounted
on the component side of the board as close to the
VDD pin as possible. No vias should be used between
the decoupling capacitor and VDD pin. The PCB trace
to VDD pin should be kept as short as possible, as
should the PCB trace to the ground via.
2) To minimize EMI, the 27
series termination resistor
(if needed) should be placed close to the clock output.
3) An optimum layout is one with all components on the
same side of the board, minimizing vias through other
signal layers. Other signal traces should be routed
away from the ICS7151. This includes signal traces just
underneath the device, or on layers adjacent to the
ground plane layer used by the device.
Crystal Information
The crystal used should be a fundamental mode (do
not use third overtone), parallel resonant. Crystal
capacitors should be connected from pins X1 to ground
and X2 to ground to optimize the initial accuracy. The
value of these capacitors is given by the following
equation:
Crystal caps (pF) = (CL - 6) x 2
In the equation, CL is the crystal load capacitance. So,
for a crystal with a 16 pF load capacitance, two 20 pF
[(16-6) x 2] capacitors should be used.
Spread Spectrum Profile
The ICS7151 low EMI clock generator uses a triangular
frequency modulation profile for optimal down stream
tracking of zero delay buffers and other PLL devices.
The frequency modulation amplitude is constant with
variations of the input frequency.
Time
Fr
eq
ue
nc
y
Modulation Rate
相关PDF资料
PDF描述
ICS7151MI-10 33.4 MHz, OTHER CLOCK GENERATOR, PDSO8
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ICS7151M-20T 66.7 MHz, OTHER CLOCK GENERATOR, PDSO8
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