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MK2745-21
DVD/MPEG Clock Source
Description
The MK2745-21 is a low cost, low jitter, high
performance clock synthesizer for DVD and other
MPEG 2 based applications. Using analog PhaseLocked Loop (PLL) techniques, the device accepts
a 27.00MHz fundamental mode crystal or clock
input to produce multiple output clocks including
the processor clock, the processor clock divided by
two, 27 MHz, 24.576 MHz, and a selectable
audio clock. The audio clocks are frequency
locked to the 27.00MHz input using our patented
zero ppm error techniques, allowing audio and
video to track exactly, thereby eliminating the
need for large buffer memory.
MicroClock manufactures the largest variety of
DVD, Set-Top Box, and multimedia clock
synthesizers for all applications. Consult
MicroClock to eliminate crystals and oscillators
from your board.
Block Diagram
VDD
GND
2
2
Features
• Packaged in 16 pin narrow (150 mil) SOIC
• Ideal for LuxSonor’s DVD solutions
• 3.3V upgrade to MK2744
• Patented zero ppm audio clock error for 256X and
384X sampling rates
• Selectable audio sampling frequencies support
32 kHz, 44.1 kHz, and 48 kHz in most DACs
• 27.00 MHz fundamental crystal or clock input
• Eight selectable processor frequencies
• Fixed clocks of 27 and 24.576 MHz
• Zero ppm error in all clocks
• Full CMOS outputs with 25mA output drive
capability at TTL levels
• Advanced, low power, sub-micron CMOS process
• 3.0V to 5.5V operating voltage
• See also the MK2712 for NTSC/PAL clocks
AS2:0
3
Clock Synthesis
and Control
PS1:0
2
clock or
crystal
X1
X2
MDS 2745-21 B 1 Revision 120400 Printed 12/5/00
Clock
Buffer/
Crystal
Oscillator
Circuitry
÷ 2
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
Output
Buffer
Audio Clock
24.576 MHz
Processor Clock27.00 MHz
PCLK/2
27 MHz
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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Pin Assignment
MK2745-21
PS1 PS0
X2
X1/ICLK
VDD
GND
ACLK
1
2
3
4
5
6
16
15
14
13
12
11
24.576M
PCLK/2
VDD
AS1
GND
DVD/MPEG Clock Source
Audio Clock (in MHz)
Decoding Table
AS2 AS1 AS0 ACLK
0 0 0 12.288
0 0 1 11.2896
0 1 0 8.192
0 1 1 24.576
1 0 0 8.192
1 0 1 16.9344
1 1 0 18.432
1 1 1 11.2896
MK2745-21
Processor Clock (in MHz)
PS1 PS0 PCLK PCLK/2
0 0 66.66 33.33
0 1 80 40
1 0 50 25
1 1 60 30
0 = connect directly to ground
1 = connect directly to VDD
PCLK
AS2
7
8
10
27M
9
AS0
16 pin (150 mil) SOIC
Pin Descriptions
Number Name Type Description
1 PS1 I Processor clock Select 1. Selects processor clock outputs per table above.
2 X2 XO Crystal connection. Connect to 27 MHz crystal. Leave unconnected for clock input.
3 X1/ICLK XI Crystal connection. Connect to 27 MHz crystal or connect to 27 MHz input clock.
4 VDD P Connect to +3.3 V or +5 V. Must be same as other VDD.
5 GND P Connect to ground.
6 ACLK O Audio Clock output. Determined by status of AS2, AS1, AS0. See table above.
7 PCLK O Processor Clock output. Determined by status of PS1, PS0. See table above.
8 AS2 I Audio clock Select 2. Selects audio clock on pin 6 per table above.
9 AS0 I Audio clock Select 0. Selects audio clock on pin 6 per table above.
10 27M O 27.00 MHz clock output.
11 GND P Connect to ground.
12 AS1 I Audio clock Select 1. Selects audio clock on pin 6 per table above.
13 VDD P Connect to +3.3 V or +5 V. Must be same as other VDD.
14 PCLK/2 O Processor Clock divided by two output. Determined by status of PS1, PS0. See table above.
15 24.576M O 24.576 MHz clock output.
16 PS0 I Processor clock Select 0. Selects processor clock outputs per table above.
Key: I = Input, O = output, P = power supply connection
MDS 2745-21 B 2 Revision 120400 Printed 12/5/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
Page 3
MK2745-21
ABSOLUTE MAXIMUM RATINGS (note 1)
DC CHARACTERISTICS (VDD = 5.0V unless noted)
AC CHARACTERISTICS (VDD = 5.0V unless noted)
exposure to levels above the operating limits but below the Absolute Maximums may affect device reliability.
2. With Processor clock at 50MHz, and ACLK at 16.93MHz.
DVD/MPEG Clock Source
Electrical Specifications
Parameter Conditions Minimum Typical Maximum Units
Supply voltage, VDD Referenced to GND 7 V
Inputs and Clock Outputs Referenced to GND -0.5 VDD+0.5 V
Ambient Operating Temperature 0 70 °C
Soldering Temperature Max of 20 seconds 260 °C
Storage temperature -65 150 °C
Operating Voltage, VDD 3 5.5 V
Input High Voltage, VIH, X1/ICLK pin only VDD/2 + 1 VDD/2 V
Input Low Voltage, VIL, X1/ICLK pin only VDD/2 VDD/2 - 1 V
Input High Voltage, VIH 2 V
Input Low Voltage, VIL 0.8 V
Output High Voltage, VOH IOH=-25mA 2.4 V
Output Low Voltage, VOL IOL=25mA 0.4 V
Output High Voltage, VOH, CMOS level IOH=-8mA VDD-0.4 V
Operating Supply Current, IDD No Load, note 2 37 mA
Short Circuit Current Each output ±100 mA
Input Capacitance 7 pF
Input Frequency 27.000 MHz
Output Clock Rise Time 0.8 to 2.0V 1.5 ns
Output Clock Fall Time 2.0 to 0.8V 1.5 ns
Output Clock Duty Cycle At VDD/2 40 60 %
Frequency error, all clocks 0 1 ppm
Absolute Jitter, short term Variation from mean 200 ps
Notes: 1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged
External Components
The MK2745-21 requires a minimum number of external components for proper operation. Decoupling
capacitors of 0.1µF should be connected between VDD and GND, as close to the MK2745-21 as possible.
A series termination resistor of 33Ω may be used for each clock output. If a clock input is not used, the
27.00 MHz crystal must be connected as close to the chip as possible. The crystal should be a fundamental
mode (do not use third overtone), parallel resonant, 50ppm or better. Crystal capacitors should be
connected from pins X1 to ground and X2 to ground. The value of these capacitors is given by the
following equation, where CL is the crystal load capacitance: Crystal caps (pF) = (CL-6) x 2. So for a crystal
with 16pF load capacitance, two 20pF caps should be used.
MDS 2745-21 B 3 Revision 120400 Printed 12/5/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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MK2745-21
Inches
Millimeters
DVD/MPEG Clock Source
Package Outline and Package Dimensions
E H
h x 45°
D
Q
e
b
c
16 pin SOIC narrow
Symbol Min Max Min Max
A 0.055 0.070 1.397 1.778
b 0.013 0.019 0.330 0.483
c 0.007 0.010 0.191 0.254
D 0.385 0.400 9.779 10.160
E 0.150 0.160 3.810 4.064
H 0.225 0.245 5.715 6.223
e
h 0.016 0.406
Q 0.004 0.01 0.102 0.254
A
Ordering Information
Part/Order Number Marking Shipping packaging Package Temperature
MK2745-21S MK2745-21S tubes 16 pin narrow SOIC 0-70°C
MK2745-21STR MK2745-21S tape and reel 16 pin narrow SOIC 0-70°C
Rev. 03318, version A . First publication, Preliminary.
Rev. 04218, version B. Corrected VDD, VIH/VIL under DC Characteristics. Preliminary.
While the information presented herein has been checked for both accuracy and reliability, MicroClock Incorporated 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 MicroClock. MicroClock reserves the right to change any circuitry or specifications without notice. MicroClock does not
authorize or warrant any MicroClock product for use in life support devices or critical medical instruments.
MDS 2745-21 B 4 Revision 120400 Printed 12/5/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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