input. Also on the chip is the ability to generate a
1.25x clock of the reference plus the reference,
making it possible to generate 20 and 25 MHz
clocks from a 20 MHz crystal.
Features
• Packaged as 8 pin SOIC
• For Fast Ethernet plus SCSI on computer
motherboards
• For AC97 sound on computer motherboards
• Less than 1 ppm synthesis error
• Input crystal frequency of 14.31818 MHz
• Operating voltages of 3.0 to 5.5V
• Available in industrial temperature
• Full CMOS level outputs with 25mA drive
capability at TTL levels
• Ideal for oscillator replacement
• Advanced, low power CMOS process
Block Diagram
VDD GND
2
S1, S0
PLL
Clock
Synthesis
and Control
Circuitry
Crystal
Oscillator
X2
Output
Buffer
CLK1
14.31818MHz
crystal
X1
or clock
Output
Buffer
CLK2
1
Revision 120799
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA•95126• (408)295-9800tel • www.icst.com
MDS 1449B C
MK1449B
Sound/SCSI+Fast Ethernet Clock
Pin Assignment
X1/ICLK
VDD
GND
CLK2
1
2
3
4
8
7
6
5
X2
S1
S0
CLK1
Clock Decoding Table (MHz)
S1
0
0
1
1
S0
0
1
0
1
CLK1
test
40
49.152
x1.25
CLK2
test
25
12.288
Reference
0 = connect directly to ground.
1 = connect directly to VDD.
In the 1,1 mode, crystals or clocks from
5 to 27 MHz can be used as an input.
Pin Descriptions
Number
1
2
3
4
5
6
7
8
Name
X1/ICLK
VDD
GND
CLK2
CLK1
S0
S1
X2
Type
I
P
P
O
O
I
I
O
Description
Crystal connection or clock input. Connect to a 14.31818MHz parallel resonant crystal.
Connect to +3.3V or +5V.
Connect to ground.
Clock 2 output per Table above.
Clock 1 output per Table above.
Select 0 for output clocks. Connect to GND or VDD. See table above.
Select 1 for output clocks. Connect to GND or VDD. See table above.
Crystal connection to a 14.31818 MHz crystal. Leave unconnected for clock input.
Key: I = Input, O = output, P = power supply connection
2
Revision 120799
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA•95126• (408)295-9800tel • www.icst.com
MDS 1449B C
MK1449B
Sound/SCSI+Fast Ethernet Clock
Electrical Specifications
Parameter
Conditions
Minimum
Typical
ABSOLUTE MAXIMUM RATINGS (stresses beyond these can permanently damage the device)
Supply Voltage, VDD
Referenced to GND
Inputs
Referenced to GND
-0.5
Clock Output
Referenced to GND
-0.5
Ambient Operating Temperature
0
Industrial temperature
-40
Soldering Temperature
Max of 10 seconds
Storage temperature
-65
DC CHARACTERISTICS (VDD = 3.3V unless otherwise noted)
Operating Voltage, VDD
3
Input High Voltage, VIH, ICLK only
ICLK (Pin 1)
(VDD/2)+1
VDD/2
Input Low Voltage, VIL, ICLK only
ICLK (Pin 1)
VDD/2
Input High Voltage, VIH
S0, S1
VDD-0.5
Input Low Voltage, VIL
S0, S1
Output High Voltage, VOH
IOH=-25mA
2.4
Output Low Voltage, VOL
IOL=25mA
IDD Operating Supply Current, 5V
No Load, 25, 40MHz
18
IDD Operating Supply Current, 3.3V
No Load, 25, 40MHz
10
Short Circuit Current
CLK output
±70
On-Chip Pull-up Resistor
Pin 7
270
Input Capacitance, S1, S0
Pins 6, 7
4
AC CHARACTERISTICS (VDD = 3.3V unless otherwise noted)
Input Frequency, crystal input
10
14.31818
Input Frequency, clock input
10
14.31818
Output Frequency
VDD = 3.0 to 5.5V
10
Output Clock Rise Time
0.8 to 2.0V
1
Output Clock Fall Time
2.0 to 0.8V
1
Output Clock Duty Cycle
at VDD/2
40
49 to 51
Synthesis error, 25, 40 MHz
Synthesis error, 12.288, 49.152 MHz
Absolute Clock Period Jitter, 20 pF load
Deviation from mean
±240
One Sigma Clock Period Jitter, 20 pF load
100
Maximum
7
VDD+0.5
VDD+0.5
70
85
260
150
5.5
(VDD/2)-1
0.5
0.4
Units
V
V
V
°C
°C
°C
°C
V
V
V
V
V
V
V
mA
mA
mA
kΩ
pF
MHz
MHz
MHz
ns
ns
%
ppm
ppm
ps
ps
27
50
75
60
1
1
3
Revision 120799
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA•95126• (408)295-9800tel • www.icst.com
MDS 1449B C
MK1449B
Sound/SCSI+Fast Ethernet Clock
External Components / Crystal Selection
The MK1449B requires a 0.01µF decoupling capacitor to be connected between VDD and GND. It must
be connected close to the MK1449B to minimize lead inductance. No external power supply filtering is
required for this device. 33Ω terminating resistors can be used next to the CLK pins. The total on-chip
capacitance is approximately 13 pF, so a parallel resonant, fundamental mode crystal should be used. For
crystals with a specified load capacitance greater than 13 pF, crystal capacitors should be connected from
each of the pins X1 and X2 to ground. The value (in pF) of these crystal caps should be = (C
L
-13)*2,
where C
L
is the crystal load capacitance in pF. These external capacitors are only required for applications
where the exact frequency is critical. For a clock input, connect to X1 and leave X2 unconnected (no
capacitors on either).
Package Outline and Package Dimensions
(For current dimensional specifications, see JEDEC pub. no. 95)
8 pin SOIC
E
Pin 1
H
Inches
Symbol Min
Max
A
0.053 0.069
A1
0.004 0.0098
B
0.013 0.020
C
0.0075 0.0098
D
0.189 0.197
E
0.150 0.157
H
0.228 0.244
e
.050 BSC
L
0.016
0.05
Millimeters
Min
Max
1.35
1.75
0.10
0.25
0.33
0.51
0.19
0.25
4.80
5.00
3.80
4.00
5.80
6.20
1.27 BSC
0.41
1.27
D
A1
e
B
C
L
A
Ordering Information
Part/Order Number
MK1449S
MK1449STR
MK1449SI
MK1449SITR
Marking
MK1449S
MK1449S
MK1449SI
MK1449SI
Package
8 pin SOIC
8 pin SOIC on tape and reel
8 pin SOIC
8 pin SOIC on tape and reel
Temperature
0 to 70 °C
0 to 70 °C
-40 to 85 °C
-40 to 85 °C
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems, Inc. (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.
4
Revision 120799
Printed 11/15/00
Integrated Circuit Systems, Inc. • 525 Race Street • San Jose •CA•95126• (408)295-9800tel • www.icst.com
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
