DATASHEET
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 Phase-Locked Loop (PLL)
techniques, the device accepts a 27 MHz fundamental
mode crystal or clock input to produce multiple audio output
clocks, a 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 MHz using
our patented zero ppm error techniques. This allows audio
and video to track exactly, thereby eliminating the need for
large buffer memory.
IDT manufactures a large variety of DVD, Set-top Box, and
multimedia clock synthesizers for all applications. Consult
IDT to eliminate crystals and oscillators from your board.
MK2745-21
Features
•
•
•
•
Packaged in a 16-pin narrow (150 mil) SOIC
Ideal for LuxSonor’s DVD solutions
3.3 V upgrade to the MK2744
Patented zero ppm audio clock error for 256x and 384x
sampling rates
and 48 kHz in most DACs
•
Selectable audio sampling frequencies support 32, 44.1,
•
•
•
•
•
•
•
•
VDD
2
27 MHz fundamental crystal or clock input
Eight selectable processor frequencies
Fixed clocks of 27 and 24.576 MHz
Zero ppm in all clocks
25 mA output drive capability at TTL levels
Advanced, low-power, sub-micron CMOS process
Operating voltage of 3.0 V to 5.5 V
See also the MK2712 for NTSC/PAL clocks
Block Diagram
AS2:0
3
Audio Clock
Clock
Synthesis and
Control
Circuitry
/2
24.576 MHz
Processor Clock
PCLK/2
PS1:0
27 MHz crystal
or clock
X1
2
Clock Buffer/
Crystal
Ocsillator
X2
2
GND
27 MHz
IDT™
DVD/MPEG CLOCK SOURCE
1
MK2745-21
REV F 051310
MK2745-21
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
Pin Assignment
PS1
X2
X1/ICLK
VDD
GND
ACLK
PCLK
AS2
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
PS0
24.576M
PCLK/2
VDD
AS1
GND
27M
AS0
Audio Clock (MHz) DecodingTable
AS2 AS1 AS0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
ACLK
12.288
11.2896
8.192
24.576
8.192
16.9344
18.432
11.2896
16-pin (150 mil) SOIC
Processor Clock (MHz)
PS1 PS0
0
0
1
1
0
1
0
1
PCLK
66.66
80
50
60
PCLK/2
33.33
40
25
30
0 = connect directly to ground
1 = connect directly to VDD
Pin Descriptions
Pin
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
Pin
Name
PS1
X2
X1/ICLK
VDD
GND
ACLK
PCLK
AS2
AS0
27M
GND
AS1
VDD
Pin
Type
Input
XO
XI
Power
Power
Output
Output
Input
Input
Output
Power
Input
Power
Pin Description
Processor clock Select 1. Selects processor clock outputs per table above.
Crystal connection. Connect to 27 MHz crystal. Leave unconnected for clock
input.
Crystal connection. Connect to 27 MHz crystal or to a 27 MHz input clock.
Connect to +3.3 V or +5 V. Must be same as other VDD.
Connect to ground.
Audio Clock output. Determined by status of AS2, AS1, AS0. See table above.
Processor Clock output. Determined by status of PS1, PS0. See table above.
Audio clock Select 2. Selects audio clock on pin 6 per table above.
Audio clock Select 0. Selects audio clock on pin 6 per table above.
27 MHz clock output.
Connect to ground.
Audio clock Select 1. Selects audio clock on pin 6 per table above.
Connect to +3.3 V or +5 V. Must be same as other VDD.
IDT™
DVD/MPEG CLOCK SOURCE
2
MK2745-21
REV F 051310
MK2745-21
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
Pin
Number
14
15
16
Pin
Name
PCLK/2
24.576M
PS0
Pin
Type
Output
Output
Input
Pin Description
Processor Clock divided by two output. Determined by status of PS1, PS0. See
table above.
24.576 MHz clock output.
Processor clock Select 0. Selects processor clock outputs per table above.
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 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, 50 ppm 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 16 pF load capacitance, two 20 pF caps should be used.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2745-21. These ratings, which are
standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at these
or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Item
Supply Voltage, VDD
All Inputs and Outputs
Ambient Operating Temperature
Storage Temperature
Junction Temperature
Soldering Temperature
7V
Rating
-0.5 V to VDD+0.5 V
0 to +70° C
-65 to +150° C
125° C
260° C
IDT™
DVD/MPEG CLOCK SOURCE
3
MK2745-21
REV F 051310
MK2745-21
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Min.
0
+3.0
Typ.
Max.
+70
+5.5
Units
°
C
V
DC Electrical Characteristics
VDD = 5.0 V (unless noted),
Temp 0 to +70°
C
Parameter
Operating Voltage
Input High Voltage
Input Low Voltage
Input High Voltage
Input Low Voltage
Output High Voltage
Output Low Voltage
Output High Voltage
Operating Supply Current
Short Circuit Current
Input Capacitance
Symbol
VDD
V
IH
V
IL
V
IH
V
IL
V
OH
V
OL
V
OH
IDD
I
OS
C
IN
Conditions
X1/ICLK pin only
X1/ICLK pin only
Min.
3.0
(VDD/2)+1
Typ.
Max.
5.5
(VDD/2)-1
Units
V
V
V
V
V
V
V
V
mA
mA
pF
2
0.8
I
OH
= -25 mA
I
OL
= 25 mA
I
OH
= -8 mA
No Load, Note 1
Each output
VDD-0.4
37
±100
7
2.4
0.4
Note 1: With processor clock at 50 MHz and ACLK at 16.93 MHz.
AC Electrical Characteristics
VDD = 5.0 V (unless noted),
Temp 0 to +70° C
Parameter
Input Frequency
Output Clock Rise Time
Output Clock Fall Time
Output Clock Duty Cycle
Frequency Error
Absolute Jitter, short term
Symbol
t
OR
t
OF
Conditions
0.8 to 2.0 V
2.0 to 0.8 V
at VDD/2
Variation from mean
Min.
Typ.
27
Max. Units
MHz
1.5
1.5
ns
ns
%
ppm
ps
40
0
200
60
1
Thermal Characteristics
Parameter
Thermal Resistance Junction to
Ambient
Symbol
θ
JA
θ
JA
θ
JA
θ
JC
Conditions
Still air
1 m/s air flow
3 m/s air flow
Min.
Typ.
120
115
105
58
Max. Units
°
C/W
°
C/W
°
C/W
°
C/W
Thermal Resistance Junction to Case
IDT™
DVD/MPEG CLOCK SOURCE
4
MK2745-21
REV F 051310
MK2745-21
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
Package Outline and Package Dimensions
(16-pin SOIC, 150 Mil. Narrow Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters
Symbol
Min
Max
Inches
Min
Max
16
E
INDEX
AREA
H
1 2
D
A
A1
B
C
D
E
e
H
h
L
α
1.35
1.75
0.10
0.25
0.33
0.51
0.19
0.25
9.80
10.00
3.80
4.00
1.27 BASIC
5.80
6.20
0.25
0.50
0.40
1.27
0
°
8
°
.0532
.0688
.0040
.0098
.013
.020
.0075
.0098
.3859
.3937
.1497
.1574
0.050 BASIC
.2284
.2440
.010
.020
.016
.050
0
°
8
°
A
A1
h x 45
C
-C-
e
B
SEATING
PLANE
L
.10 (.004)
C
Ordering Information
Part / Order Number
MK2745-21SLF
MK2745-21SLFTR
Marking
2745-21SLF
2745-21SLF
Shipping Packaging
Tubes
Tape and Reel
Package
16-pin SOIC
16-pin SOIC
Temperature
0 to 70° C
0 to 70° C
“LF” denotes Pb (lead) free package
While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology (IDT) 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 IDT. IDT reserves the right to change any circuitry or specifications without notice. IDT
does not authorize or warrant any IDT product for use in life support devices or critical medical instruments.
IDT™
DVD/MPEG CLOCK SOURCE
5
MK2745-21
REV F 051310
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