MK2049-03SITR [ICSI]

Communications Clock PLLs; 通信时钟锁相环
MK2049-03SITR
型号: MK2049-03SITR
厂家: INTEGRATED CIRCUIT SOLUTION INC    INTEGRATED CIRCUIT SOLUTION INC
描述:

Communications Clock PLLs
通信时钟锁相环

晶体 外围集成电路 光电二极管 通信 时钟
文件: 总12页 (文件大小:150K)
中文:  中文翻译
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MK2049-02/03  
Communications Clock PLLs  
Description  
Features  
The MK2049-02 and MK2049-03 are Phase-  
Locked Loop (PLL) based clock synthesizers that  
accept multiple input frequencies. With an 8 kHz  
clock input as a reference, the MK2049-02/03  
generate T1, E1, T3, E3, ISDN, xDSL, and other  
communications frequencies. This allows for the  
generation of clocks frequency-locked and phase-  
locked to an 8 kHz backplane clock, simplifying  
clock synchronization in communications systems.  
The MK2049-02/03 can also accept a T1, E1, T3,  
or E3 input clock and provide the same output for  
loop timing. All outputs are frequency-locked  
together and to the input.  
• Packaged in 20 pin SOIC  
• Fixed input-output phase relationship on most  
clock selections  
• Meets the TR62411, ETS300 011, and GR-1244  
specification for MTIE, Pull-in/Hold-in Range,  
Phase Transients, and Jitter Generation for  
Stratum 3, 4, and 4E  
Accept multiple inputs: 8 kHz backplane clock,  
Loop Timing frequencies, or 10-28 MHz  
• Lock to 8 kHz ±100 ppm (External mode)  
• Buffer Mode allows jitter attenuation of  
10–28 MHz input and x1/x0.5 or x2/x4 outputs  
• Exact internal ratios enable zero ppm error  
• Output clock rates include T1, E1, T3, E3, ISDN,  
xDSL, and OC3 submultiples  
These parts also have a jitter-attenuated buffer  
capability. In this mode, the MK2049-02/03 are  
ideal for filtering jitter from 27 MHz video clocks  
or other clocks with high jitter.  
ICS/MicroClock can customize these devices for  
many other different frequencies. Contact your  
ICS/MicroClock representative for more details.  
• 5 V ±5% operation. Refer to MK2049-34 for 3.3 V  
Block Diagram  
VDD  
GND  
4
3
RESET  
4
FS3:0  
PLL  
Clock  
Synthesis,  
Control, and  
Jitter  
Attenuation  
Circuitry  
Output  
Buffer  
CLK1  
CLK2  
External/  
Clock  
Output  
Buffer  
Loop Timing  
Input  
Mux  
Reference  
Crystal  
X1  
Output  
Buffer  
Crystal  
CLK3  
8 kHz  
Oscillator  
(External  
Mode only)  
X2  
CAP1  
1
CAP2  
MDS 2049-02/03 B  
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
Pin Assignment  
1
20  
19 RESET  
FS1  
FS0  
2
X2  
X1  
3
18  
17  
16  
15  
14  
13  
CAP2  
4
VDD  
VDD  
VDD  
GND  
CLK2  
CLK1  
CLK3  
GND  
CAP1  
5
6
VDD  
GND  
ICLK  
7
8
9
12 FS3  
11 FS2  
10  
20 pin (300 mil) SOIC  
Pin Descriptions  
Number  
Name  
FS1  
Type Description  
Frequency Select 1. Determines CLK input/outputs per tables on pages 4 & 5.  
1
I
2
X2  
XO Crystal connection. Connect to a MHz crystal as shown in the tables on pages 4 & 5.  
XI Crystal connection. Connect to a MHz crystal as shown in the tables on pages 4 & 5.  
3
X1  
4
VDD  
VDD  
VDD  
GND  
CLK2  
CLK1  
CLK3  
FS2  
P
P
P
P
O
O
O
I
Connect to +5V.  
5
Connect to +5V.  
6
Connect to +5V.  
7
Connect to ground.  
8
Clock 2 output determined by status of FS3:0 per tables on pages 4 & 5.  
Clock 1 output determined by status of FS3:0 per tables on pages 4 & 5. Always 1/2 of CLK2.  
Clock 3 as shown in tables on pages 4 &5; typically recovered 8 kHz clock output.  
Frequency Select 2. Determines CLK input/outputs per tables on pages 4 & 5.  
Frequency Select 3. Determines CLK input/outputs per tables on pages 4 & 5.  
Input clock connection. Connect to 8 kHz backplane or MHz clock.  
Connect to ground.  
9
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
FS3  
I
ICLK  
GND  
VDD  
CAP1  
GND  
CAP2  
RESET  
FS0  
I
P
P
Connect to +5V.  
LF Connect the loop filter ceramic capacitors and resistor between this pin and CAP2.  
Connect to ground.  
LF Connect the loop filter ceramic capacitors and resistor between this pin and CAP1.  
P
I
I
Reset pin. Resets internal PLL when low. Outputs will stop low. Internal pull-up resistor.  
Frequency Select 0. Determines CLK input/outputs per tables on pages 4 & 5.  
Type: XI, XO = crystal connections, I = Input, O = output, P = power supply connection, LF = loop filter  
connections  
MDS 2049-02/03 B  
2
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
Electrical Specifications  
Parameter  
Conditions  
Minimum  
Typical  
Maximum  
Units  
ABSOLUTE MAXIMUM RATINGS (Note 1)  
Supply Voltage, VDD  
Referenced to GND  
7
VDD+0.5  
70  
V
V
Inputs and Clock Outputs  
Ambient Operating Temperature  
-0.5  
0
MK2049-0xS  
°C  
°C  
°C  
°C  
MK2049-0xSI  
Max of 10 seconds  
-40  
85  
Soldering Temperature  
Storage Temperature  
250  
-65  
150  
DC CHARACTERISTICS (VDD = 5V unless noted)  
Operating Voltage, VDD  
4.75  
2
5
5.25  
0.8  
V
V
Input High Voltage, VIH  
Input Low Voltage, VIL  
V
Input High Voltage, VIH  
Input Low Voltage, VIL  
Output High Voltage  
Pin 19 only  
VDD-0.5  
V
Pin 19 only  
0.5  
V
IOH=-4 mA  
IOH=-8 mA  
IOL=8 mA  
VDD-0.4  
2.4  
V
Output High Voltage  
V
Output Low Voltage  
0.4  
V
Operating Supply Current, IDD  
Short Circuit Current  
No Load, VDD=5.0V  
Each output  
20  
±100  
7
mA  
mA  
pF  
Input Capacitance, FS3:0  
AC CHARACTERISTICS (VDD = 5V unless noted)  
Input Frequency, External Mode  
Input Clock Pulse Width  
ICLK  
8.000  
0
kHz  
ns  
10  
40  
Propagation Delay  
ICLK to CLK2  
CLK1 to CLK2, Note 2  
0.8 to 2.0 V  
2
500  
1.5  
1.5  
60  
0
ns  
Output-Output Skew, Zero Delay Selections  
Output Clock Rise Time  
ps  
ns  
Output Clock Fall Time  
2.0 to 0.8 V  
ns  
Output Clock Duty Cycle, High Time  
Actual mean frequency error versus target  
At VDD/2  
%
Any clock selection  
0
ppm  
Notes:  
1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged exposure  
to levels above the operating limits but below the Absolute Maximums may affect device reliability.  
2. CLK1 in the MK2049-02 may have the rising or falling edge aligned with the rising edge of CLK2. See the INPUT AND  
OUTPUT SYNCHRONIZATION section for more details.  
MDS 2049-02/03 B  
3
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
MK2049-02 Output Decoding Table – External Mode (MHz)  
ICLK  
FS3 FS2 FS1 FS0  
CLK1  
(Note 3)  
1.544  
CLK2  
Crystal  
CLK3  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
0
0
0
0
0
0
0
0
1
1
0
0
0
0
1
1
1
1
1
1
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
0
1
0
1
3.088  
4.096  
44.736  
34.368  
38.88  
32.768  
49.152  
51.84  
12.352  
12.288  
11.184  
11.456  
12.96  
8.192  
12.288  
12.96  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
2.048  
22.368  
17.184  
19.44  
16.384  
24.576  
25.92  
10.24  
4.096  
20.48  
8.192  
10.24  
12.288  
MK2049-02 Output Decoding Table – Loop Timing Mode (MHz)  
ICLK  
FS3 FS2 FS1 FS0  
CLK1  
(Note 3)  
1.544  
2.048  
22.368  
17.184  
CLK2  
Crystal  
CLK3  
1.544  
2.048  
44.736  
34.368  
1
1
1
1
0
0
0
0
0
0
1
1
0
1
0
1
3.088  
4.096  
44.736  
34.368  
12.352  
12.288  
11.184  
11.456  
N/A  
N/A  
N/A  
N/A  
MK2049-02 Output Decoding Table – Buffer Mode (MHz)  
ICLK  
FS3 FS2 FS1 FS0  
CLK1  
CLK2  
Crystal  
CLK3  
(Note 3)  
ICLK/2  
2*ICLK 4*ICLK  
19 - 28  
10 - 14  
1
1
1
1
1
1
0
1
ICLK ICLK/2  
ICLK  
N/A  
N/A  
• 0 = connect directly to ground, 1 = connect directly to VDD.  
• Crystal is connected to pins 2 and 3; clock input is applied to pin 13.  
= No Zero (Fixed) I/O Delay for these selections shown in the shaded boxes.  
Note 3: CLK1 rising or falling edge may align with the input clock. See Figure 1 on page 6  
for more details.  
MDS 2049-02/03 B  
4
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
MK2049-03 Output Decoding Table – External Mode (MHz)  
ICLK  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
FS3 FS2 FS1 FS0  
CLK1  
1.544  
2.048  
18.688  
7.68  
19.44  
16.384  
24.576  
8.64  
12.416  
18.528  
10.24  
4.096  
CLK2  
3.088  
4.096  
37.376  
15.36  
38.88  
32.768  
49.152  
17.28  
24.832  
37.056  
20.48  
8.192  
CLK3  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
8 kHz  
Crystal  
12.352  
12.288  
9.344  
10.24  
9.72  
8.192  
12.288  
11.52  
12.416  
0
0
0
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
1
0
0
0
1
0
1
0
1
0
1
0
1
0
1
1.544 MHz  
8 kHz  
12.352  
10.24  
8.192  
8 kHz  
= No Zero (Fixed) I/O Delay for these selections shown in the shaded boxes.  
MK2049-03 Output Decoding Table – Loop Timing Mode (MHz) for T1/E1  
ICLK  
1.544  
2.048  
FS3 FS2 FS1 FS0  
CLK1  
1.544  
2.048  
CLK2  
3.088  
4.096  
Crystal  
12.352  
12.288  
CLK3  
N/A  
1
1
0
0
0
0
0
1
N/A  
MK2049-03 Output Decoding Table – Buffer Mode (MHz)  
ICLK  
19 - 28  
10 - 14  
FS3 FS2 FS1 FS0  
CLK1  
CLK2  
ICLK ICLK/2  
ICLK  
Crystal  
CLK3  
N/A  
1
1
1
1
1
1
0
1
ICLK/2  
2*ICLK 4*ICLK  
Low  
• 0 = connect directly to ground, 1 = connect directly to VDD.  
• Crystal is connected to pins 2 and 3; clock input is applied to pin 13.  
OPERATING MODES  
The MK2049-02/03 have three operating modes: External, Loop Timing, and Buffer. Although each  
mode uses an input clock to generate various output clocks, there are important differences in their input  
and crystal requirements.  
External Mode  
The MK2049-02/03 accept an external 8 kHz clock and will produce a number of common communica-  
tion clock frequencies. The 8 kHz input clock does not need to have a 50% duty cycle; a “high” or “on”  
pulse as narrow as 10 ns is acceptable. In the MK2049-02, the rising edge of CLK2 is aligned with the  
rising edge of the 8 kHz ICLK; refer to Figure 1 for more details. In the MK2049-03, the rising edges of  
CLK1 and CLK2 are both aligned with the rising edge of the 8 kHz ICLK (unless noted in the shaded area  
of the table); refer to Figure 2 for more details.  
MDS 2049-02/03 B  
5
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
OPERATING MODES (continued)  
Loop Timing Mode  
This mode can be used to remove the jitter from standard high-frequency communication clocks. For T1  
and E1 inputs, the CLK1 output will be the same as the input frequency, with CLK2 at twice the input  
frequency. For T3 and E3 inputs, CLK1 will be 1/2 the input frequency and CLK2 will be the same as the  
input frequency.  
Buffer Mode  
Unlike the other two modes that accept only a single specified input frequency, Buffer Mode will accept a  
wider range of input clocks. The input jitter is attenuated, and the outputs on CLK1 and CLK2 also  
provide the option of getting x1, x2, x4, or 1/2 of the input frequency. For example, this mode can be used  
to remove the jitter from a 27 MHz clock, generating low-jitter 27 MHz and 13.5 MHz outputs.  
INPUT AND OUTPUT SYNCHRONIZATION  
As shown in the tables on pages 4 and 5, the MK2049-02/03 offer a Zero Delay feature in most selections.  
In these selections, there is an internal feedback path between ICLK and the CLK2 output clock. This  
provides a fixed phase relationship between the input and output, a requirement in many communications  
systems.  
MK2049-02  
As illustrated in the diagram below, when using the MK2049-02 in one of the Zero Delay selections, the  
rising edge of ICLK will be aligned with the rising edge of CLK2. However, the CLK1 edge in these cases  
will be either rising or falling. (8 kHz is used in this illustration, but the same is true for the Zero Delay  
selections in the Loop Timing and Buffer modes.)  
ICLK (8 kHz)  
CLK2 (MHz)  
CLK1 (MHz)  
Figure 1. MK2049-02 Input and Output Clock Waveforms in Zero Delay Selections  
MDS 2049-02/03 B  
6
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
INPUT AND OUTPUT SYNCHRONIZATION (continued)  
MK2049-03  
As illustrated in the diagram below, when using the MK2049-03 in one of the Zero Delay selections, the  
rising edge of ICLK will be aligned with the rising edges of CLK1 and CLK2.  
ICLK (8 kHz)  
CLK2 (MHz)  
CLK1 (MHz)  
Figure 2. MK2049-03 Input and Output Clock Waveforms in Zero Delay Selections  
In the MK2049-02 and MK2049-03 selections that are not Zero Delay, the phase relationship between the  
input and output clocks is not predictable. Although it will not change once the MK2049-02/03 is running,  
this relationship is likely to change when power is interrupted.  
Measuring Zero Delay on the MK2049  
The MK2049-02/03 both produce low-jitter output clocks. In addition, both parts have a very low  
bandwidth--on the order of a few Hertz. Since most 8 kHz input clocks will have high jitter, this can make  
measuring the input-to-output skew (zero delay feature) very difficult. The MK2049 are designed to reject  
the input jitter; when the input and output clocks are both displayed on an oscilloscope, they may appear  
not to be locked because the scope trigger point is constantly changing with the input jitter. In fact, the  
input and output clocks probably are locked, and the MK2049 will have zero delay to the average position  
of the 8 kHz input clock. In order to see this clearly, a low jitter 8 kHz input clock is necessary. Most lab  
frequency sources are NOT SUITABLE for this since they have high jitter at low frequencies.  
Frequency Locking to the Input  
In all modes, the output clocks are frequency-locked to the input. The output 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.  
MDS 2049-02/03 B  
7
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
LAYOUT AND EXTERNAL COMPONENTS  
The MK2049-02/03 require a minimum number of external components for proper operation. Decoupling  
capacitors of 0.01µF must be connected between VDD and GND pins close to the chip (especially pins 4  
and 7, 15 and 17), and 33 Wterminating resistors should be used on clock outputs with traces longer than 1  
inch (assuming 50 Wtraces).  
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 5 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 W  
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 MAN05 for additional suggestions on layout of the crystal section.  
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 MicroClock 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 described in the section titled “Determining the Crystal Frequency Adjustment  
Capacitors”.  
Cutout in ground and power plane.  
Route all traces away from this area.  
cap  
Optional;  
see text  
G
1
2
3
4
5
6
7
8
9
10  
20  
19  
cap  
resist.  
cap  
18  
cap  
V
17  
G
V
cap  
16  
15  
cap  
14  
13  
12  
11  
=connect to VDD  
resist.  
V
G
=connect to GND  
resist.  
Figure 3. Typical MK2049-02/03 Layout  
MDS 2049-02/03 B  
8
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
LAYOUT AND EXTERNAL COMPONENTS (continued)  
External Components Selection  
The external loop filter should be connected between CAP1 and CAP2 as shown in Figure 4 below, and as  
close to the chip as possible. High quality ceramic capacitors are recommended. DO NOT use any type of  
polarized or electrolytic capacitor. Ceramic capacitors should have C0G or NP0 dielectric. Another  
alternative is the Panasonic PPS polymer dielectric series; their part number for the 0.1 µF cap is  
ECHU1C104JB5. Avoid high-K dielectrics like Z5U and X7R; these and other ceramics which have  
piezolectric properties allow mechanical vibration in the system to increase the output jitter because the  
mechanical energy is converted directly to voltage noise on the VCO input.  
CAP2  
470 kW  
0.015 µF  
0.1 µF  
CAP1  
Figure 4. Loop Filter Component Values  
Typical component values are shown. Contact the ICS MicroClock applications  
department at (408)297-1201 for the recommended values for your application.  
Crystal Operation  
The MK2049 operates by phase locking the input signal to a VCXO which consists of the special  
recommended crystal and the integrated VCXO oscillator circuit on the MK2049. To achieve the best  
performance and reliability, the layout guidelines shown on the previous page must be closely followed.  
The frequency of oscillation of a quartz crystal is determined by its cut and by the load capacitors connected  
to it. The MK2049 has variable load capacitors on-chip which “pull”, or change the frequency of the crystal.  
External stray capacitance must be kept to a minimum to ensure maximum pullability of the crystal. To  
achieve this, the layout should use short traces between the MK2049 and the crystal.  
MDS 2049-02/03 B  
9
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
LAYOUT AND EXTERNAL COMPONENTS (continued)  
Crystal Specifications  
Parameter  
Minimum  
Typical  
Maximum  
Units  
C
Operating Temperature Range  
Initial Accuracy at 25 C  
Temperature stability  
Aging, first year  
0
25  
70  
20  
30  
5
-20  
-30  
-5  
ppm  
ppm  
ppm  
ppm  
Aging, 10 years  
-20  
20  
Load Capacitance  
Note 1  
Shunt Capacitance, C0  
Motional Capacitance, C1  
C0/C1 ratio  
7
pF  
pF  
none  
none  
250  
35  
none  
Ohms  
Equivalent Series Resistance  
*This ratio decreases for lower crystal frequencies.  
Note 1: Nominal crystal load capacitance specification varies with frequency.  
Contact the ICS MicroClock applications department at (408)297-1201.  
Note 2: The third overtone mode of the crystal and all spurs must be >200 ppm  
away from 3x the fundamental resonance shown in the table below.  
For recommended crystal devices, please contact the ICS MicroClock application department  
at 408-297-1201.  
MDS 2049-02/03 B  
10  
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
LAYOUT AND EXTERNAL COMPONENTS (continued)  
Determining the Crystal Frequency Adjustment Capacitors  
To determine the crystal adjustment capacitor values, you will need a PC board of your final layout, a  
frequency counter capable of less than 1 ppm resolution and accuracy, two power supplies, and some samples  
of the crystals which you plan to use in production, along with measured initial accuracy for each crystal at  
the specified load capacitance, C .  
L
To determine the value of the crystal capacitors:  
1. Connect VDD of the MK2049 to 5.0 V. Connect pin 18 of the MK2049 to the second power supply.  
Adjust the voltage on pin 18 to 0.0 V. Measure and record the frequency of the CLK1 or CLK2 output .  
2. Adjust the voltage on pin 18 to 3.0 V. Measure and record the frequency of the same output.  
To calculate the centering error:  
(f  
- f  
) + (f  
- f  
)
3.0V target  
0.0V target  
Centering  
error  
6
- error  
= 10  
xtal  
f
target  
Where f  
target  
= 44.736000 MHz, for example, and error  
= actual initial accuracy (in ppm) of the  
xtal  
crystal being measured.  
If the centering error is less than ±15 ppm, no adjustment is needed. If the centering error is more than  
15 ppm negative, the PC board has too much stray capacitance and will need to be redone with a new layout  
to reduce stray capacitance. (The crystal may be re-specified to a lower load capacitance instead. Contact ICS  
MicroClock for details.) If the centering error is more than 15 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:  
External Capacitor = 2*(centering error)/(trim sensitivity)  
Trim sensitivity is a parameter which can be supplied by your crystal vendor. If you do not know the value,  
assume it is 30 ppm/pF. After any changes, repeat the measurement to verify that the remaining error is  
acceptably low (less than ±15 ppm).  
The MicroClock Applications department can perform this procedure on your board. Call us at 408-295-  
9800, and we will arrange for you to send us a PC board (stuffed or unstuffed) and one of your crystals. We  
will calculate the value of capacitors needed.  
MDS 2049-02/03 B  
11  
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  
MK2049-02/03  
Communications Clock PLLs  
Package Outline and Package Dimensions  
(For current dimensional specifications, see JEDEC Publication No. 95.)  
20 pin SOIC  
Inches  
Millimeters  
Symbol Min  
Max  
0.104  
--  
Min  
Max  
2.65  
--  
A
A1  
B
C
D
E
--  
--  
0.0040  
0.10  
0.33  
0.18  
E
H
0.013 0.020  
0.007 0.013  
0.51  
0.33  
13.00  
7.60  
INDEX  
AREA  
0.496 0.512 12.60  
0.291 0.299  
.050 BSC  
7.40  
e
1.27 BSC  
1
2
H
h
0.394 0.419 10.01  
10.64  
0.74  
1.27  
0.01  
0.029  
0.25  
0.41  
h x 45°  
D
L
0.016 0.050  
A
A1  
C
B
e
L
Ordering Information  
Part/Order Number  
Marking  
Package  
Temperature  
MK2049-02S  
MK2049-02STR  
MK2049-02SI  
MK2049-02S  
MK2049-02S  
MK2049-02SI  
MK2049-02SI  
MK2049-03S  
MK2049-03S  
MK2049-03SI  
MK2049-03SI  
20 pin SOIC  
Add Tape & Reel  
20 pin SOIC  
0 to 70 °C  
0 to 70 °C  
-40 to 85 °C  
-40 to 85 °C  
0 to 70 °C  
MK2049-02SITR  
MK2049-03S  
Add Tape & Reel  
20 pin SOIC  
MK2049-03STR  
MK2049-03SI  
Add Tape & Reel  
20 pin SOIC  
0 to 70 °C  
-40 to 85 °C  
-40 to 85 °C  
MK2049-03SITR  
Add Tape & Reel  
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems (ICS) assumes no responsibility for either its use or for the  
infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in  
normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements  
are not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any  
ICS product for use in life support devices or critical medical instruments.  
MDS 2049-02/03 B  
12  
Revision 040601  
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose • CA • 95126 • (408)295-9800tel• www.icst.com  

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