The MK3234 is the smallest size, lowest power system
clock synthesizer available. It is the ideal way to
generate clocks for portable computers and other
devices where low power is required. Using analog
Phase-Locked Loop (PLL) techniques, the device
operates from a single 32.768 kHz crystal to produce
the 32.768kHz, CPU, and ISA bus (system) output
clocks.
The device has an individual power down pin for the
CPU clock, and a power down pin for the entire device.
The MK3234 can save board space and cost even if it
only replaces the 32kHz oscillator circuitry and one
additional surface mount crystal or oscillator. The
extremely low IDD, the ease of surface mounting, the
upgradeability of CPU frequencies, and the power
down capability are added benefits in using the part.
MK3234
Portable System Clock Synthesizer
Features
• Input crystal frequency of 32.768 kHz
• Lowest power solution available
• Lowest profile clock solution where height is critical
• Output clock frequencies up to 50 MHz
• Three output clocks
• 3.3V or 5.0V operation
• Duty cycle of 45/55
• Eight selectable CPU frequencies
• CPU clock power down
• Separate battery supply pin for 32 kHz runs to 2V
• IDD less than 4µA when 32 kHz running
• Packaged in 16 pin narrow (0.150”) SOIC
Block Diagram
VDD
GND
CPUS0
CPUS1
CPUS2
PDCPU
CPU
Clock Synthesis
and Control
Circuitry
Output
Buffer
CPUCLK
PD
VDD32
32.768 kHz
crystal
X1
Crystal
Oscillator
X2
System
Clock Synthesis
and Control
Circuitry
Output
Buffer
14.318 MHz
Output
Buffer
32.768 kHz
1
Revision 022798
Printed 11/16/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
MDS 3234 C
I C R O
C
LOC K
Pin Assignment
CPUS2
X2
X1
VDD32
VDD
GND
32K
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CPUS1
CPUS0
CPUCLK
VDD
GND
14.3M
PD
PDCPU
MK3234
Portable System Clock Synthesizer
CPU Clock Decoding
CPUS2 CPUS1 CPUS0 CPUCLK (MHz)
0
0
0
8.00
0
0
1
13.00
0
1
0
16.00
0
1
1
20.00
1
0
0
40.00
1
0
1
25.00
1
1
0
50.00
1
1
1
33.33
Frequency transitions will occur smoothly.
Pin Descriptions
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
CPUS2
X2
X1
VDD32
VDD
GND
32K
GND
PDCPU
PD
14.3M
GND
VDD
CPUCLK
CPUS0
CPUS1
Type
I
O
I
P
P
P
O
P
I
I
O
P
P
O
I
I
Description
Select 2 for CPUCLK frequencies. See Table above.
Crystal connection. Connect to 32.768 kHz crystal.
Crystal connection. Connect to 32.768 kHz crystal.
Separate power supply connection for 32.768kHz clock. Will operate to 2.0V.
Connect to +3.3V or +5V. Must be the same voltage as pin 13.
Connect to ground.
32.768 kHz square wave clock output.
Connect to ground.
Power Down CPU clock output (stops low) when low.
Powers Down everything but 32kHz oscillator internally. 32kHz output buffer is off.
14.318 MHz clock output. Do not use to drive video CRT controller.
Connect to ground.
Connect to +3.3V or +5V. Must be the same voltage as pin 5.
CPUCLK output. See Table above.
Select 0 for CPUCLK frequencies. See Table above.
Select 1 for CPUCLK frequencies. See Table above.
Type: I = Input, O = output, P = power supply connection
Power Down status:
Output clocks will stop in a low state when powered down
External Components
The MK3234 requires a minimum number of external components for proper operation. Decoupling
capacitors of 0.1µF should be connected between VDD and GND, and VDD32 and GND, as close to the
MK3234 as possible. A series resistor of 10kΩ should be used on the VDD32 supply. A series termination
resistor of 33Ω may be used for each clock output, except the 32.768 kHz. For tuning the real time clock
output, use a 32.768 kHz crystal with a load capacitance of 12.5pF, and connect a 20pF±5% (NPO
dielectric) capacitor between each crystal pin and ground. The 32.768 kHz crystal must be connected as
close to the chip as possible. The 14.3 MHz output is not suitable for driving CRT displays. A separate
14.318 MHz crystal should be used at the input to the graphics controller chip. Consult MicroClock for a
recommended external circuit schematic.
2
Revision 022798
Printed 11/16/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
MDS 3234 C
I C R O
C
LOC K
Electrical Specifications
Parameter
Supply Voltage, VDD
Inputs and Clock Outputs
Ambient Operating Temperature
Soldering Temperature
Storage Temperature
Operating Voltage, VDD
Operating Voltage,VDD32
Input High Voltage, VIH
Input Low Voltage, VIL
Output High Voltage, VOH
Output Low Voltage, VOL
Input High Voltage, VIH
Input Low Voltage, VIL
Output High Voltage, VOH
Output Low Voltage, VOL
IDD Operating Supply Current, 5V
IDD32 with only 32 kHz running, 5V
IDD Operating Supply Current, 3.3V
IDD32 with only 32 kHz output running, 3.3V
IDD32, only 32 kHz osc. running, 3.3V, note 2
Short Circuit Current, 5V
Short Circuit Current, 5V
Input Capacitance
Input Frequency
Output Clock Rise and Fall Time, 0.2 to 0.8VDD
Output Clock Duty Cycle, all MHz clocks
32.768 kHz Clock Duty Cycle
Absolute Clock Period Jitter, CPU clock
Power up time, CPU off to 50 MHz, 32k running
Transition time, 8 MHz to 50 MHz
Transition time, 50 MHz to 8 MHz
Power on time,VDD32=0V to all clocks stable
Power on time, all power down pins taken high
Conditions
MK3234
Portable System Clock Synthesizer
Minimum
Typical
Maximum
7
VDD+0.5
70
260
150
5.5
5.5
0.8
2.4
0.4
1.9
0.4
2.4
0.4
15
3.5
9
2.5
1
±30
±100
7
32.768
Units
V
V
°C
°C
°C
V
V
V
V
V
V
V
V
V
V
mA
µA
mA
µA
µA
mA
mA
pF
kHz
ns
%
%
ps
ms
ms
ms
ms
ms
ABSOLUTE MAXIMUM RATINGS (note 1)
Referenced to GND
Referenced to GND
Max of 30 seconds
-65
3.0
2.0
2.0
-0.5
0
DC CHARACTERISTICS (at 5.0V unless otherwise noted)
VDD=5V
VDD=5V
VDD=5V, IOH=-25mA
VDD=5V, IOL=25mA
VDD=3.3V
VDD=3.3V
VDD=3.3V, IOH=-8mA
VDD=3.3V, IOL=8mA
No Load, 50MHz
No Load
No Load, 50MHz
No Load
32kHz output off. PD=0
32 kHz output
CPU output
AC CHARACTERISTICS (at 5.0V unless otherwise noted)
2
55
500
9
4
2.5
500
15
At VDD/2
45
At VDD32/2
20 to 50 MHz
-500
VDD=3.3 or 5V
VDD=3.3 or 5V
VDD=3.3 or 5V
32.768kHz crystal with ESR
≤25kΩ
32.768kHz oscillator running
49 to 51
57
1000
Note 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.
Note 2: When PD=0 (low) and VDD32 is greater than 2.0V, then the 32kHz oscillator will continue to run on the chip, but the
output is turned off. This allows for a quick power-up (<20ms), while the chip is only consuming approximately 1µA.
3
Revision 022798
Printed 11/16/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
MDS 3234 C
I C R O
C
LOC K
Package Outline and Package Dimensions
MK3234
Portable System Clock Synthesizer
16 pin SOIC narrow
Symbol
A
b
c
D
E
H
e
h
Q
Inches
Min
Max
0.055 0.068
0.013 0.019
0.007 0.010
0.385 0.400
0.150 0.160
0.225 0.245
.050 BSC
0.016
0.004
0.01
Millimeters
Min
Max
1.397 1.7272
0.330
0.483
0.191
0.254
9.779 10.160
3.810
4.064
5.715
6.223
1.27 BSC
0.406
0.102
0.254
E
H
D
Q
e
c
h x 45°
A
b
Ordering Information
Part/Order Number
MK3234-01S
MK3234-01STR
Marking
MK3234-01S
MK3234-01S
Package
16 pin SOIC
Add Tape & Reel
Temperature
0-70°C
0-70°C
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.
4
Revision 022798
Printed 11/16/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
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