MK2761
Set-Top Clock Source
MDS 2761 A
1
Revision 041796
Printed 11/16/00
MicroClock Division of ICS1271
Parkmoor Ave.San JoseCA95126(408)295-9800tel(408)295-9818fax
P R E L I M I N A R Y I N F O R M A T I O N
I C R O
C
LOC K
Block Diagram
Description
Features
The MK2761 is a low cost, low jitter, high
performance clock synthesizer designed for
set-top boxes. Using analog Phase-Locked Loop
(PLL) techniques, the device accepts a 27.00MHz
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 27MHz. The audio clocks are exactly
frequency locked to the 27.00MHz input with
zero ppm error, allowing audio and video to track
exactly.
MicroClock manufactures the largest variety of
Set-Top Box and multimedia clock synthesizers
for all applications. Consult MicroClock to
eliminate crystals and oscillators from your board.
Packaged in 16 pin narrow (150 mil) SOIC
Selectable audio sampling frequencies support
32 kHz, 44.1 kHz, and 48 kHz in most DACs
27.00 MHz crystal or clock input
Processor frequency of 16.67MHz
Zero ppm error in audio clocks exactly track video
frequency
25mA output drive capability at TTL levels
Advanced, low power, sub-micron CMOS process
5V10% operating voltage
Crystal
Oscillator
VDD
GND
Clock
Synthesis
Circuitry
Output
Buffer
Output
Buffer
27.000 MHz
Output
Buffers
3.6864 MHz
Audio Clock
Output
Buffer
16.667 MHz
3
2
2
ACS1:0
27.000 MHz
crystal or
clock
X1
X2
4
MK2761
Set-Top Clock Source
MDS 2761 A
2
Revision 041796
Printed 11/16/00
MicroClock Division of ICS1271
Parkmoor Ave.San JoseCA95126(408)295-9800tel(408)295-9818fax
P R E L I M I N A R Y I N F O R M A T I O N
I C R O
C
LOC K
Pin Descriptions
Key: I = Input, O = output, P = power supply connection
Pin Assignment
Number
Name
Type
Description
1
ACS1
I
Audio Clock Select 1. Selects ACLK on pin 8. See table above.
2
X2
O
Crystal connection. Connect to 27 MHz crystal. Leave unconnected for clock input.
3
X1/ICLK
I
Crystal connection. Connect to 27 MHz crystal or connect to 27 MHz input clock.
4
VDD
P
Connect to +5V.
5
GND
P
Connect to ground.
6
16.67M
O
16.667 MHz processor clock output.
7
3.68M
O
3.6864 MHz clock output.
8
ACLK
O
Audio Clock output. Determined by status of ACS1, ACS0. See table above.
9
GND
P
Connect to ground.
10
27M
O
27.00 MHz buffered reference clock output. Duty cycle matches input clock.
11
27M
O
27.00 MHz buffered reference clock output. Duty cycle matches input clock.
12
GND
P
Connect to ground.
13
VDD
P
Connect to +5V.
14
27M
O
27.00 MHz buffered reference clock output. Duty cycle matches input clock.
15
27M
O
27.00 MHz buffered reference clock output. Duty cycle matches input clock.
16
ACS0
I
Audio Clock Select 0. Selects audio clock on pin 8. See table above.
1
16
2
3
4
15
14
13
VDD
GND
X2
VDD
GND
16 pin narrow (150 mil) SOIC
5
6
7
8
12
11
10
9
ACLK
27MHz
X1/ICLK
ACS1
27MHz
ACS0
27MHz
27MHz
GND
3.68MHz
16.67MHz
ACS1 ACS0 ACLK (MHz)
0
0
8.192
0
1
11.2896
1
0
12.288
1
1
5.6448
MK2761
Set-Top Clock Source
MDS 2761 A
3
Revision 041796
Printed 11/16/00
MicroClock Division of ICS1271
Parkmoor Ave.San JoseCA95126(408)295-9800tel(408)295-9818fax
P R E L I M I N A R Y I N F O R M A T I O N
I C R O
C
LOC K
Parameter
Conditions
Minimum
Typical
Maximum
Units
ABSOLUTE MAXIMUM RATINGS (note 1)
ABSOLUTE MAXIMUM RATINGS (note 1)
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 10 seconds
260
C
Storage temperature
-65
150
C
DC CHARACTERISTICS (VDD = 5.0V unless noted)
DC CHARACTERISTICS (VDD = 5.0V unless noted)
Operating Voltage, VDD
4.5
5.5
V
Input High Voltage, VIH, X1/ICLK pin only
3.5
2.5
V
Input Low Voltage, VIL, X1/ICLK pin only
2.5
1.5
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
45
mA
Short Circuit Current
Each output
100
mA
Input Capacitance
7
pF
Frequency error, ACLK
0
ppm
AC CHARACTERISTICS (VDD = 5.0V unless noted)
AC CHARACTERISTICS (VDD = 5.0V unless noted)
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 1.4V
40
60
%
Maximum Absolute Jitter, short term
200
ps
Skew of 27 MHz outputs
Rising edges at 1.4V
-500
0
500
ps
Electrical Specifications
Notes:
1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged
exposure to levels above the operating limits but below the Absolute Maximums may affect device reliability.
2. With ACLK at 12.28MHz.
External Components
The MK2761 requires a minimum number of external components for proper operation. Decoupling
capacitors of 0.1F should be connected between VDD and GND (pins 4 and 5, and 13 and 12), as close
to the MK2761 as possible. A series termination resistor of 33
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, parallel resonant, 50 ppm or better. Crystal capacitors should be
connected from pins X1 to ground and X2 to ground. The value (in pF) of these crystal capacitors should
be = (C
L
-4)*2, where C
L
is the crystal load capacitance in pF. So for a crystal with 16pF load capacitance,
the crystal capacitors should be 24pF each.
MK2761
Set-Top Clock Source
MDS 2761 A
4
Revision 041796
Printed 11/16/00
MicroClock Division of ICS1271
Parkmoor Ave.San JoseCA95126(408)295-9800tel(408)295-9818fax
P R E L I M I N A R Y I N F O R M A T I O N
I C R O
C
LOC K
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.
Package Outline and Package Dimensions
Ordering Information
Part/Order Number
Marking
Shipping packaging
Package
Temperature
MK2761S
MK2761S
tubes
16 pin SOIC
0-70C
MK2761STR
MK2761S
tape and reel
16 pin SOIC
0-70C
16 pin SOIC narrow
Inches
Inches
Millimeters
Millimeters
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 .050 BSC
.050 BSC
1.27 BSC
1.27 BSC
h
0.016
0.406
Q
0.004
0.01
0.102
0.254
b
D
E
H
e
Q
c
h x 45
A
PDF 
ZIP