DATASHEET
DVD/MPEG CLOCK SOURCE
Description
The MK2746 is a low cost, low jitter, high performance clock
synthesizer for DVD and other MPEG2 based applications.
Using analog Phase Locked Loop (PLL) techniques, the
device accepts a 27 MHz fundamental mode crystal or
clock input to produce multiple output clocks including the
processor clock, audio clock, bus driver clock, SDRAM
clock and a Video clock. The audio clocks are frequency
locked to the 27 MHz input using our patented zero ppm
error techniques, allowing audio and video to track exactly,
thereby eliminating the need for large buffer memory.
IDT manufacturers the largest variety of DVD, set top box,
and multimedia clock synthesizers for all applications.
MK2746
Features
•
Packaged in 16 pin TSSOP
•
Operating voltage of 3.3 V
•
Provides tight jitter controlled selectable processor clock
per table.
•
Provides selectable audio clock per table.
•
Provides fixed outputs of 27 MHz (Video), 50 MHz
(DSP/Bus clock) and 133.33 MHz (SDRAM).
•
Advanced, low power, sub-micron CMOS process
Block Diagram
VDD
3
Audio
AS1:0
PLL / Clock
Circuit
PS1:0
27 MHz crystal
or clock
X1
Clock Buffer/
Crystal
Ocsillator
Processor
(Tight Jitter)
50M Bus Clock
133.33 M SDRAM Clock
27M Video Clock
X2
2
GND
IDT™
DVD/MPEG CLOCK SOURCE
1
MK2746
REV C 051310
MK2746
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
Pin Assignment
X2
X1/ICLK
VDD
GND
PCLK
PS0
133.33M
PS1
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VDD
27M
AS0
ACLK
AS1
VDD
GND
50M
Clock Output Select Table
in MHz
AS1
0
0
1
1
AS0
0
1
0
1
Audio CLK
12.288
11.2896
18.432
8.192
PS1
0
0
1
1
PS0
0
1
0
1
Processor
CLK
66.66
41.66
50
58.33
16 pin (173 mil) TSSOP
0 = connect directly to GND
1 = connect directly to VDD
Pin Descriptions
Pin
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Pin
Name
X2
X1/ICLK
VDD
GND
PCLK
PS0
133.33M
PS1
50M
GND
VDD
AS1
ACLK
AS0
27M
VDD
Pin
Type
Input
Input
Power
Power
Output
Input
Output
Input
Output
Power
Power
Input
Output
Input
Output
Power
Pin Description
Connect to a 27 MHz fundamental mode crystal. Leave open for clock input.
Connect to a 27 MHz fundamental mode crystal or clock.
Connect to +3.3 V.
Connect to ground
Processor clock output. Determined by the status of PS1, PS0 per table
above.
Processor Clock select 0. Selects processor clock per table above.
SDRAM clock output.
Processor Clock select 1. Selects processor clock per table above.
50 MHz clock output.
Connect to ground.
Connect to +3.3 V.
Audio clock select 1. Selects audio clock per table above.
Audio clock output determined by the status of PS1, PS0.
Audio clock select 0. Selects audio clock per table above.
27 MHz clock output.
Connect to +3.3 V.
IDT™
DVD/MPEG CLOCK SOURCE
2
MK2746
REV C 051310
MK2746
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
External Component Selection
The MK2746 requires a minimum number of external
components for proper operation.
PCB Layout Recommendations
For optimum device performance and lowest output phase
noise, the following guidelines should be observed.
1) The 0.01µF decoupling capacitor should be mounted on
the component side of the board as close to the VDD pin as
possible. No vias should be used between decoupling
capacitor and VDD pin. The PCB trace to VDD pin should
be kept as short as possible, as should the PCB trace to the
ground via. Distance of the ferrite bead and bulk decoupling
from the device is less critical.
2) The external crystal should be mounted just next to the
device with short traces. The X1 and X2 traces should not
be routed next to each other with minimum spaces, instead
they should be separated and away from other traces.
3) To minimize EMI the 33Ω series termination resistor, if
needed, should be placed close to the clock output.
4) An optimum layout is one with all components on the
same side of the board, minimizing vias through other signal
layers (the ferrite bead and bulk decoupling capacitor can be
mounted on the back). Other signal traces should be routed
away from the MK2746. This includes signal traces just
underneath the device, or on layers adjacent to the ground
plane layer used by the device.
Decoupling Capacitors
Decoupling capacitors of 0.01µF should be connected
between VDD and GND as close to the MK2746 as
possible. For optimum device performance, the decoupling
capacitors should be mounted on the component side of the
PCB. Avoid the use of vias in the decoupling circuit.
Series Termination Resistor
When the PCB traces between the clock outputs and the
loads are over 1 inch, series termination should be used. To
series terminate a 50Ω trace (a commonly used trace
impedance) place a 33Ω resistor in series with the clock line,
as close to the clock output pin as possible. The nominal
impedance of the clock output is 20Ω
.
Crystal Tuning Load Capacitors
For a crystal input, a parallel resonant fundamental mode
crystal should be used. Crystal capacitors must be
connected between each of the pins X1 and X2 to ground.
The value (in pF) of these crystal caps should equal
(CL-6)*2. In this equation CL is equal to the crystal load
capacitance in pF. As an example, for a crystal with an 18 pF
load capacitance, each crystal capacitor would be 24 pF
[(18-6)*2=24].
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2746. 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
Soldering Temperature
7V
Rating
-0.5 V to VDD+0.5 V
0 to +70° C
-65 to +150° C
260° C
IDT™
DVD/MPEG CLOCK SOURCE
3
MK2746
REV C 051310
MK2746
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
+3.6
Units
°
C
V
DC Electrical Characteristics
VDD=3.3 V ±10%
, Ambient temperature 0 to +70° C, unless stated otherwise
Parameter
Operating Voltage
Input High Voltage
Input Low Voltage
Input High Voltage
Input Low Voltage
Output High Voltage
Output Low Voltage
Output High Voltage (CMOS
Level)
Operating Supply Current
Short Circuit Current
Input Capacitance
Nominal Output Impedance
On Chip Pull-up Resistor
Symbol
VDD
V
IH
V
IL
V
IH
V
IL
V
OH
V
OL
V
OH
IDD
I
OS
C
IN
Z
OUT
R
PU
Conditions
input selects
input selects
ICLK
ICLK
I
OH
= -12 mA
I
OL
= 12 mA
I
OH
= -4 mA
No load
Min.
3.0
2.0
Typ.
Max.
3.6
0.8
Units
V
V
V
V
V
V
V
V
(VDD/2)-1
2.4
VDD/2
VDD/2
(VDD/2)+1
0.4
VDD-0.4
40
±70
5
20
mA
mA
pF
Ω
kΩ
kΩ
AS1, AS0 pins
PS1 pin
120
510
AC Electrical Characteristics
VDD = 3.3 V ±10%
, Ambient Temperature 0 to +70° C, unless stated otherwise
Parameter
Input Frequency
Output Rise Time
Output Fall Time
Output Clock Duty Cycle
Maximum Output Jitter,
short term, peak to peak
Maximum Output Jitter,
short term, peak to peak
Maximum Output Jitter,
long term, peak to peak
t
OR
t
OF
t
D
t
J
t
J
t
J
20% to 80% of VDD, Note 1
80% to 20% of VDD, Note 1
at VDD/2, Note 1
PCLK output, Note 1
All clocks, except PCLK,
Note 1
1000 cycles, except ACLK,
Note 1
40
Symbol
Conditions
Min.
Typ.
27
1.0
1.0
50
+100
+200
750
Max. Units
MHz
1.8
1.8
60
ns
ns
%
ps
ps
ps
Note 1: Measured with 15 pF Load.
IDT™
DVD/MPEG CLOCK SOURCE
4
MK2746
REV C 051310
MK2746
DVD/MPEG CLOCK SOURCE
VCXO AND SYNTHESIZER
Package Outline and Package Dimensions
(16-pin TSSOP, 4.40 mm Body, 0.65 mm Pitch)
Package dimensions are kept current with JEDEC Publication No. 95
16
Millimeters
Symbol
Min
Max
Inches*
Min
Max
E1
IN D EX
AR EA
E
1
2
D
A
A1
A2
b
C
D
E
E1
e
L
α
aaa
--
1.20
0.05
0.15
0.80
1.05
0.19
0.30
0.09
0.20
4.90
5.1
6.40 BASIC
4.30
4.50
0.65 Basic
0.45
0.75
0°
8°
--
0.10
--
0.047
0.002
0.006
0.032
0.041
0.007
0.012
0.0035 0.008
0.193
0.201
0.252 BASIC
0.169
0.177
0.0256 Basic
0.018
0.030
0°
8°
--
0.004
A
2
A
1
A
*For reference only. Controlling dimensions in mm.
c
-C -
e
b
S E A TIN G
P LA N E
L
aaa
C
Ordering Information
Part / Order Number
MK2746GLF
MK2746GLFT
Marking
MK2746GL
MK2746GL
Shipping Packaging
Tubes
Tape and Reel
Package
16-pin TSSOP
16-pin TSSOP
Temperature
0 to +70° C
0 to +70° C
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
MK2746
REV C 051310
实时操作系统RTOS
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