參數(shù)資料
型號(hào): MK2049-36SILFTR
元件分類: 時(shí)鐘產(chǎn)生/分配
英文描述: 155.52 MHz, OTHER CLOCK GENERATOR, PDSO20
封裝: 0.300 INCH, SOIC-20
文件頁數(shù): 4/7頁
文件大?。?/td> 137K
代理商: MK2049-36SILFTR
3.3 Volt Communications Clock PLL
MDS 2049-36 D
4
Revision 031505
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126 tel (408) 297-1201
www.icst.com
MK2049-36
Frequency Locking to the Input
In all modes, the output clocks are frequency-locked to the input. The outputs will remain at the specified output
frequency as long as the combined variation of the input frequency and the crystal does not exceed 100 ppm. For
example, if the crystal can vary ±40 ppm (initial accuracy + temperature + aging), then the input frequency can vary
by up to 60 ppm and still have the output clock remain frequency-locked.
PC Board Layout
A proper board layout is critical to the successful use of the MK2049. In particular, the CAP1 and CAP2 pins are
very sensitive to noise and leakage (CAP2 at pin 18 is the most sensitive). Traces must be as short as possible and
the two capacitors and resistor must be mounted next to the device as shown below. The capacitor shown between
pins 15 and 17, and the one between pins 4 and 7 are the power supply decoupling capacitors. The high frequency
output clocks on pins 8 and 9 should have a series termination of 33
connected close to the pin. Additional
improvements will come from keeping all components on the same side of the board, minimizing vias through other
signal layers, and routing other signals away from the MK2049. You may also refer to application note MAN05 for
additional suggestions on layout of the crystal selection.
The crystal traces should include pads for small capacitors from X1 and X2 to ground. These are used to adjust the
stray capacitance of the board to match the crystal load capacitance. The typical telecom reference frequency is
accurate to much less than 1 ppm, so the MK2049 may lock and run properly even if the board capacitance is not
adjusted with these fixed capacitors. However, ICS recommends that the adjustment capacitors be included to
minimize the effects of variation in individual crystals, temperature, and aging. The value of these capacitors
(typically 0 - 4 pF) is determined once for a given board layout, using the procedure found in application note
External Component Selection
The MK2049-36 requires a minimum number of external components for proper operation. Decoupling capacitors
of 0.01
F must be connected between VDD and GND pins close to the chip (especially pins 4 and 7, 15 and 17),
and 33
series terminating resistors should be used on clock outputs with traces longer than one inch (assuming
50
traces). The selection of additional external components is described in the following sections.
16
1
15
2
14
3
13
4
12
5
11
6
7
8
9
10
20
19
18
17
G
ca
p
ca
p
resist
cap
ca
p
ca
p
resist
V
G
cap
ca
p
Optional -
see text
Cutout in ground and power plane.
Route all traces away from this area.
V
= connect to VDD
G
= connect to GND
Figure 2. Typical MK2049-34 Layout
相關(guān)PDF資料
PDF描述
MK2049-36SI 155.52 MHz, OTHER CLOCK GENERATOR, PDSO20
MK2059-01SILFTR 25.92 MHz, OTHER CLOCK GENERATOR, PDSO20
MK2059-01SILF 25.92 MHz, OTHER CLOCK GENERATOR, PDSO20
MK2702STR 27 MHz, OTHER CLOCK GENERATOR, PDSO8
MK2702SLF 27 MHz, OTHER CLOCK GENERATOR, PDSO8
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MK2049-45 制造商:ICS 制造商全稱:ICS 功能描述:3.3V Communications Clock PLL
MK2049-45ASI 功能描述:IC CLK PLL COMM 3.3V 20-SOIC RoHS:否 類別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 時(shí)鐘發(fā)生器,PLL,頻率合成器 系列:- 標(biāo)準(zhǔn)包裝:39 系列:- 類型:* PLL:帶旁路 輸入:時(shí)鐘 輸出:時(shí)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:*
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MK2049-45ASILFTR 功能描述:時(shí)鐘發(fā)生器及支持產(chǎn)品 3.3 VOLT COMMUNICA. CLOCK VCXO PLL RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-56