MK1491-06
MDS 1491-06 J 1Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
AMD Geode™ Clock Source
Description
The MK1491-06 is a low-cost, low-jitter,
high-performance clock synthesizer for AMD’s
Geode-based computer and portable appliance
applications. Using patented analog Phased-Locked
Loop (PLL) techniques, the device accepts a 14.318
MHz crystal input to produce multiple output clocks. It
provides selectable PCI local bus and AC97 audio
clocks, 24 MHz and 48 MHz clocks for Super I/O and
USB, as well as multiple Reference outputs.
The device has multiple power-down modes to reduce
power consumption.
Features
•Packaged in 28-pin SOIC or in 28-pin SSOP
•Available in Pb (lead) free
•Provides all critical timing for the AMD Geode
companion chip
•Four PCI clocks
•Selectable PCIF on up to 2 outputs
•Early PCI clock selectability
•Up to 4 Reference clocks
•48 MHz USB and 24MHz SIO support
•AC97 audio clock
•Multiple power down modes
•Low EMI Enable pin reduces EMI radiation on PCI
clocks (patented)
•Operating voltage of 3.3 V ±5%
Block Diagram
Crystal
Oscillator
Fixed
Clocks
Audio
Clock
PCI
Clocks
MUX
PCI Frequency Select
Low EMI Enable
PCIF Function Enable
Early PCI Enable
SLOW#
PCISTP#
PWRDWN#
Audio Select
VDD GND
2
5
6
3
3PCI
EPCI/PCI
48 MHz
14.318 MHz or
24 MHz
14.318 MHz
16.394 MHz or
24.576 MHz or
49.152 MHz
14.31818 MHz
crystal
XI
XO
14.3M/24M Select
AMD Geode™ Clock Source
MDS 1491-06 J 2Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
Pin Assignment
Early PCI Control Table
EMI Control
Spread direction is DOWN.
PCI Frequency Select Table
24M/14.3M Frequency Select Table
PCIF Enable Control
PCIF continues to run in PCI STOP mode. See table on page
4.
AC97 Audio Frequency Select
Pin Descriptions
EPCI# PCI (Pin 22)
0 1 ns early
1Normal
LE# PCI Low EMI
0ON
1OFF
18
7
17
8
16
9
15
GND
10
14.3M (SEL AUDIO)
11
VDD
12
48M (LE#)
13
SLOW#
14
GND
VDD
24M/14.3M
VDD
FS GND
PWRDWN#
SEL24 PCISTP#
22
21
20
19
VDD
PCI (EPCI#)
5
6
14.3M (TS)
14.3M GND
24
23
PCI
3
4
XO
GND PCI
26
25
VDD
1
2
VDD
XI PCI
28
27
AC97 AUDIO (PEN)
TS FS PCI
0 0 Tristate all clocks
01 Reserved
M0 30 MHz
M 1 33.3 MHz
10 25 MHz
1 1 37.5 MHz
SEL24 24M/14.3M
0 14.31818 MHz
1 24.0 MHz
PEN Pin 25 Pin 24
0PCI PCI
MPCI PCIF
1 PCIF PCIF
SEL AUDIO AC97 AUDIO
0 16.9344 MHz
M 24.576 MHz
1 49.152 MHz
Pin
Number
Pin
Name
Pin
Type
Pin Description
1, 9, 14 VDD P Connect to +3.3 V. Must be same voltage on all pins.
2 XI I Crystal connection. Connect to a 14.31818 MHz crystal or input clock.
3 XO O Crystal connection. Connect to a 14.31818 MHz crystal, or leave
unconnected for clock.
4, 7, 11,
17, 23
GND P Connect to Ground.
5 14.3M (TS) TI/O 14.318 MHz output. Input control for all clocks per table above.
6 14.3M O 14.318 MHz buffered reference clock output.
AMD Geode™ Clock Source
MDS 1491-06 J 3Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
KEY:
I = Input
TI = Tri-level
O = Output
P = Power supply connection
(T)I/O = Input on power up, becomes an Output after 10 ms
Weak internal pull-up resistors are present on SEL24, EPCI#, FS, LE#, PCISTP#, and SLOW#. These pins
should be tied to VDD or GND, and not be left floating. Internal resistors on PEN, SEL AUDIO, and TS pull
to mid-level (M).
8 14.3M (SEL
AUDIO)
TI/O 14.318 MHz output and audio frequency select input per table above.
10 SLOW# I PCI normal or slow mode select input per table on page 4.
12 FS I Frequency Select for PCI clocks per table above.
13 SEL24 I Fixed frequency select input per table above. Selects frequency on pin
19.
15 PWRDWN# I Power down control; defined in table on page 4.
16 PCISTP# I PCI Stop power down control; defined in table on page 4.
18, 20, 26 VDD P Connect to +3.3 V. Must be same voltage on all pins.
19 24M/14.3M O Fixed frequency clock output per table above.
21 48 (LE#) I/O Fixed frequency clock output and low EMI (spread spectrum) enable
input per table above.
22 PCI (EPCI#) I/O PCI Output clock that can be early. Input control for Early PCI per table
above.
24 PCI O PCI Output clock. PCI/PCIF control set by PEN per table above.
25 PCI O PCI Output clock. PCI/PCIF control set by PEN per table above.
27 PCI O PCI Output clock.
28 AC97 AUDIO
(PEN)
TI/O Audio clock output and PCIF Function Enable per table above.
Pin
Number
Pin
Name
Pin
Type
Pin Description
AMD Geode™ Clock Source
MDS 1491-06 J 4Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
Power Down Control Table
Key: 1 = connected to VDD, 0 = connected to ground, X = any valid logic level, combination inputs/outputs
should be connected to VDD or ground through a 10 kΩ resistor as shown below.
Power-on Default Conditions
PCISTP# PWRDWN# SLOW# MODE PCI PCIF 24/14.3 14.3 Description
X 0 X Power down LOW LOW LOW LOW All outputs low. PLL’s
and oscillators off.
0 1 X PCI STOP LOW ON ON ON PCI clocks
synchronously enter
and leave low state.
1 1 X ON ON ON ON ON All clocks on.
Pin # Function Default Condition
5 TS M All outputs enabled.
8 SEL AUDIO M Audio clock (pin 28) set to 24.576 MHz
10 SLOW# 1 PCI clocks set to 33.3 MHz. Refer to Power Down Control Table above.
12 FS 1 PCI frequency = 33.3 MHz.
13 SEL 24 1 24M/14.3M (pin 19) set to 24 MHz.
15 PWRDWN# 1 All clocks running.
16 PCISTP# 1 PCI clocks running.
21 LE# 1 Low EMI function OFF
22 EPCI# 1 Pin 22 set to normal PCI signal (not early).
28 PEN M PCI (pin 25) set to PCI clock (33.33 MHz). PCI (pin 24) set to PCIF clock
(33.33 MHz).
AMD Geode™ Clock Source
MDS 1491-06 J 5Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
External Components
The MK1491-06 requires some inexpensive external
components for proper operation. Decoupling
capacitors of 0.1µF should be connected on each VDD
pin to ground, as close to the MK1491-06 as possible.
A series termination resistor of 33Ω may be used for
each clock output. See the discussion below for other
external resistors required for proper I/O operation. The
14.3 MHz oscillator has internal caps that provide the
proper load for a parallel resonant crystal with CL=18
pF. For tuning with other values of CL, the formula
2*(CL-18) gives the value of each capacitor that should
be connected between X1 and ground and X2 and
ground.
I/O Structure
The MK1491-06 provides more functionality in a 28-pin
package by using a unique I/O technique. The device
checks the status of all I/O pins during power-up and at
exit from the Power Down state. This status (pulled
high, low, or mid-level) then determines the frequency
selections and power down modes (see the tables on
pages 2 and 4). Within 10ms after power up, the inputs
change to outputs and the clocks start up. In the
diagrams to the right, the 33Ω resistors are the normal
output termination resistors. The 10kΩ resistor pulls
low to generate a logic zero. Weak internal pull-up
resistors are present on SEL24, EPCI#, FS, LE#,
PCISTP#, and SLOW#. These pins should be
connected directly to VDD or GND if not under active
control. Internal resistors on PEN, SEL AUDIO, and TS
pull to a mid-level (M).
*Note: Do not use a TTL load. This will overcome the
10 kΩ pull-down and force the input to a logic 1.
33
To load*
10 k
I/O
For select
= 0 (low) Do not stuff for
“1” selection
AMD Geode™ Clock Source
MDS 1491-06 J 6Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK1491-06. 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.
Recommended Operation Conditions
DC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±5%, Ambient Temperature 0 to +70°C
Item Rating
Supply Voltage, VDD 7 V
All Inputs and Outputs -0.5 V to VDD+0.5 V
Ambient Operating Temperature 0 to +70°C
Storage Temperature -65 to +150°C
Junction Temperature 125°C
Soldering Temperature 260°C
Parameter Min. Typ. Max. Units
Ambient Operating Temperature 0 +70 °C
Power Supply Voltage (measured in respect to GND) +3.15 +3.3 +3.45 V
Parameter Symbol Conditions Min. Typ. Max. Units
Operating Voltage VDD 3.15 3.3 3.45 V
Input High Voltage VIH 2V
Input Mid-level Voltage VIM 1.2 1.4 1.6 V
Input Low Voltage VIL 0.8 V
Output High Voltage VOH IOH = -8 mA 2.4 V
Output Low Voltage VOL IOL = 8 mA 0.4 V
Output High Voltage VOH IOH = -8 mA VDD-0.4 V
Operating Supply Current IDD 33 MHz, no load 30 mA
Power Down Mode Supply
Current
15 µA
Short Circuit Current,
SIngle Output Driver
VDD = 3.3 V ±60 mA
Input Capacitance CIN 7pF
AMD Geode™ Clock Source
MDS 1491-06 J 7Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±5%, Ambient Temperature 0 to +70° C
Thermal Characteristics
Parameter Symbol Conditions Min. Typ. Max. Units
Input Frequency FIN 14.31818 MHz
Output Clock Rise Time tOR 20% to 80% 1.5 ns
Output Clock Fall Time tOF 80% to 20% 1.5 ns
Output Clock Duty Cycle, all
MHz Clocks tOD At 1.5 V 45 49 to 51 55 %
PCI Output to Output Skew Rising edges at 1.5 V 500 ps
Skew of EPCI with respect to
PCI 1ns
Cycle-to-Cycle Jitter, PCI clocks 250 ps
EMI Reduction, peaks of 5th -
19th odd harmonics 33.3 MHz PCI Clock 6 11 dB
Power-up Time, PWRDWN#
High to all Clocks Stable 820ms
Power-on Time, applied VDD to
all Clocks Stable 12 25 ms
Parameter Symbol Conditions Min. Typ. Max. Units
Thermal Resistance Junction to
Ambient
θJA Still air 100 °C/W
θJA 1 m/s air flow 80 °C/W
θJA 3 m/s air flow 67 °C/W
Thermal Resistance Junction to Case θJC 60 °C/W
AMD Geode™ Clock Source
MDS 1491-06 J 8Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
Marking Diagram
Notes:
1. ###### is the lot code.
2. YYWW is the last two digits of the year, and the week number that the part was assembled.
14
28 15
######
YYWW
MK1491-06R
ICS
1
AMD Geode™ Clock Source
MDS 1491-06 J 9Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
Package Outline and Package Dimensions (28-pin SOIC, 150 mil Body)
Package dimensions are kept current with JEDEC Publication No. 95, MO-153
h x 45°
α
L
C
SEATING
PLANE
A1
B
A
e
.10 (.004)
INDEX
AREA
1 2
N
D
EH
Millimeters Inches
Symbol Min Max Min Max
A 2.65 0.104
A1 0.10 .0040
B 0.33 0.51 .013 .020
C 0.18 0.32 .007 .013
D 17.70 18.40 .697 .724
E 7.40 7.60 .291 .299
e 1.27 Basic 0.050 Basic
H 10.00 10.65 .394 .419
h 0.25 0.75 .010 .029
L 0.40 1.27 .016 .050
α0°8°0°8°
AMD Geode™ Clock Source
MDS 1491-06 J 10 Revision 110204
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
MK1491-06
Package Outline and Package Dimensions (28-pin SSOP, 150 mil Body, 0.025 mm Pitch)
Package dimensions are kept current with JEDEC Publication No. 95, MO-153
Ordering Information
“LF” denotes Pb (lead) free package.
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.
Part / Order Number Marking Shipping Packaging Package Temperature
MK1491-06R MK1491-06R Tubes 28-pin SSOP 0 to +70°C
MK1491-06RTR MK1491-06R Tape and Reel 28-pin SSOP 0 to +70°C
MK1491-06RLF MK1491-06RLF Tubes 28-pin SSOP 0 to +70°C
MK1491-06RLFTR MK1491-06RLF Tape and Reel 28-pin SSOP 0 to +70°C
MK1491-06S MK1491-06S Tubes 28-pin SOIC 0 to +70°C
MK1491-06STR MK1491-06S Tape and Reel 28-pin SOIC 0 to +70°C
MK1491-06SLF MK1491-06SLF Tubes 28-pin SOIC 0 to +70°C
MK1491-06SLFTR MK1491-06SLF Tape and Reel 28-pin SOIC 0 to +70°C
INDEX
AREA
1 2
28
D
E1 E
SEATING
PLANE
A
1
A
A
2
e
- C -
b
aaa C
c
L
Millimeters Inches
Symbol Min Max Min Max
A 1.351.75.053.069
A1 0.10 0.25 .0040 .010
A2 -- 1.50 -- .059
b 0.200.30.008.012
C 0.180.25.007.010
D 9.80 10.00 .386 .394
E 5.806.20.228.244
E1 3.80 4.00 .150 .157
e 0.635 Basic 0.025 Basic
L 0.401.27.016.050
α0°8°0°8°
aaa -- 0.10 -- 0.004
