MK2761
S
ET
-
TOP
C
LOCK
S
OURCE
Description
The MK2761 is a low-cost, low-jitter, high-performance
clock synthesizer for set-top box applications. Using
analog Phase-Locked Loop (PLL) techniques, the
device accepts a 27 MHz crystal or clock input to
produce multiple output clocks including the processor
clock, the UART clock, a selectable audio clock, and
four low skew copies of the 27 MHz. 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.
ICS manufactures a large variety of Set-top Box and
multimedia clock synthesizers for all applications.
Consult ICS to eliminate crystals and oscillators from
your board.
Features
•
Packaged in a 16-pin narrow (150 mil) SOIC
•
Selectable audio sampling frequencies support 32,
44.1, and 48 kHz in most DACs
•
•
•
•
27 MHz crystal or clock input
Processor frequency of 16.67 MHz
Fixed clocks of 27 and 24.576 MHz
Zero ppm in audio clocks exactly track video
frequency
•
25 mA output drive capability at TTL levels
•
Advanced, low-power, sub-micron CMOS process
•
Operating voltage of 5.0 V ±10%
Block Diagram
VDD
2
ACS1:0
27.000 MHz
crystal or clock
X1
2
Clock
Synthesis and
Control
Circuitry
Audio Clock
3.6864 MHz
16.667 MHz
Crystal
Ocsillator
X2
3
GND
4
27.000 MHz
MDS 2761 B
I n t e gra te d C i r c u i t S y s t e m s
●
1
525 Race Stre et, San Jo se, CA 9 5126
●
Revision 120204
te l (40 8) 2 97-12 01
●
w w w. i c st . c o m
MK2761
S
ET
-
TOP
C
LOCK
S
OURCE
Pin Assignment
ACS1
X2
X1/ICLK
VDD
GND
16.67 MHz
3.68 MHz
ACLK
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
ACS0
27 MHz
27 MHz
VDD
GND
27 MHz
27 MHz
GND
Audio Clock (MHz) DecodingTable
ACS1
0
0
1
1
ACS0
0
1
0
1
ACLK
8.192
11.2896
12.288
5.6448
16-pin (150 mil) SOIC
Pin Descriptions
Pin
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Pin
Name
ACS1
X2
X1/ICLK
VDD
GND
16.67M
3.68M
ACLK
GND
27M
27M
GND
VDD
27M
27M
ACS0
Pin
Type
Input
XO
XI
Power
Power
Output
Output
Output
Power
Output
Output
Power
Power
Output
Output
Input
Pin Description
Audio clock Select 1. Selects ACLK on pin 8. See 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 +5 V.
Connect to ground.
16.667 MHz processor clock output.
3.6864 MHz clock output.
Audio clock output. Determined by status of ACS1, ACS0. See table above
Connect to ground.
27 MHz buffered reference clock output. Duty cycle matches input clock.
27 MHz buffered reference clock output. Duty cycle matches input clock.
Connect to ground.
Connect to +5 V.
27 MHz buffered reference clock output. Duty cycle matches input clock.
27 MHz buffered reference clock output. Duty cycle matches input clock.
Audio clock Select 0. Selects audio clock on pin 8. See table above.
MDS 2761 B
In te grated Circuit Systems
●
2
525 Ra ce Street, San Jose, CA 9512 6
●
Revision 120204
tel (4 08) 297-1 201
●
w w w. i c s t . c o m
MK2761
S
ET
-
TOP
C
LOCK
S
OURCE
External Components
The MK2761 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 MK2761 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-4) x 2. So, for a crystal with 16
pF load capacitance, the crystal caps should be 24 pF each.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2761. These ratings,
which are standard values for ICS 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
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Min.
0
+4.5
Typ.
Max.
+70
+5.5
Units
°C
V
MDS 2761 B
In te grated Circuit Systems
●
3
525 Ra ce Street, San Jose, CA 9512 6
●
Revision 120204
tel (4 08) 297-1 201
●
w w w. i c s t . c o m
MK2761
S
ET
-
TOP
C
LOCK
S
OURCE
DC Electrical Characteristics
VDD = 5.0 V ±10% (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, CMOS
level
Operating Supply Current
Short Circuit Current
Input Capacitance
Frequency Error, ACLK
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.
4.5
3.5
2
Typ.
2.5
2.5
Max.
5.5
1.5
0.8
Units
V
V
V
V
V
V
V
V
I
OH
= -25 mA
I
OL
= 25 mA
I
OH
= -8 mA
No load, Note 1
Each output
2.4
0.4
VDD-0.4
45
±100
7
0
mA
mA
pF
ppm
Note 1: With ACLK clock at 12.28 MHz.
AC Electrical Characteristics
VDD = 5.0 V ±10% (unless noted),
Temp 0 to +70°C
Parameter
Input Frequency
Output Clock Rise Time
Output Clock Fall Time
Output Clock Duty Cycle
Absolute Jitter, short term
Skew of 27 MHz Outputs
Symbol
t
OR
t
OF
Conditions
0.8 to 2.0 V
2.0 to 0.8 V
At 1.4 V
Variation from mean
Rising edges at 1.4 V
Min.
Typ.
27
Max. Units
MHz
1.5
1.5
ns
ns
%
ps
500
ps
40
200
-500
0
60
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
MDS 2761 B
In te grated Circuit Systems
●
4
525 Ra ce Street, San Jose, CA 9512 6
●
Revision 120204
tel (4 08) 297-1 201
●
w w w. i c s t . c o m
MK2761
S
ET
-
TOP
C
LOCK
S
OURCE
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
MK2761S
MK2761STR
Marking
MK2761S
MK2761S
Shipping Packaging
Tubes
Tape and Reel
Package
16-pin SOIC
16-pin SOIC
Temperature
0 to 70° C
0 to 70° C
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 2761 B
In te grated Circuit Systems
●
5
525 Ra ce Street, San Jose, CA 9512 6
●
Revision 120204
tel (4 08) 297-1 201
●
w w w. i c s t . c o m
微控制器 MCU
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
