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Description
The MK3235 is the smallest size, lowest power system
clock synthesizer available. It is the ideal way to
generate clocks for handheld computers, such as PDAs,
PICs, 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, 14.318MHz, and serial
communications output clocks.
The device has three power down modes for the
14.3MHz, communications, and 32.768kHz clocks.
The MK3235 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, and
the power down capability are added benefits in using
the part.
MK3235
Handheld System Clock Synthesizer
Features
• Input crystal frequency of 32.768 kHz
• Lowest power solution available
• Lowest profile clock solution where height is critical
• Three output clocks
• 3.3V or 5.0V operation
• Duty cycle of 45/55
• 14.3MHz or 14.3MHz+Comm clock power downs
• Separate battery supply pin for 32 kHz runs to 2V
• IDD less than 4µA when 32 kHz running
• Packaged in 16 pin narrow SOIC
Block Diagram
VDD
GND
PD14
14.318MHz
Clock Synthesis
and Control
Circuitry
Output
Buffer
14.3 MHz
PDCOMM
PD
VDD32
32.768 kHz
crystal
X1
Crystal
Oscillator
X2
Communications
Clock Synthesis
and Control
Circuitry
Output
Buffer
1.843 or
3.686 MHz
Output
Buffer
32.768 kHz
MDS 3235 D
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Revision 092397
Printed 11/16/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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Pin Assignment
X2
X1
VDD32
VDD
GND
COMMCLK
32K
PDCOMM
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
GND
VDD
PD14
GND
14.3M
PD
GND
MK3235
Handheld System Clock Synthesizer
Pin Descriptions
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
X2
X1
VDD32
VDD
GND
COMMCLK
32K
PDCOMM
GND
PD
14.3M
GND
PD14
VDD
GND
GND
Type
O
I
P
P
P
O
O
I
P
I
O
P
I
P
P
P
Description
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 14.
Connect to ground.
Serial communications (1.84 on -01 version, or 3.68MHz on -02 version) clock output.
32.768 kHz square wave clock output.
Power Down serial Communications and 14.3M clock outputs (stop low) when low.
Connect to ground.
Powers Down everything but 32kHz oscillator internally. 32kHz output buffer is off.
14.318 MHz output clock.
Connect to ground.
Power Down 14.318MHz clock output (stops low) when low.
Connect to +3.3V or +5V. Must be the same voltage as pin 4.
Connect to ground.
Connect to ground.
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 MK3235 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
MK3235 as possible. A series resistor 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. Consult MicroClock for a recommended external circuit schematic.
MDS 3235 D
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Revision 092397
Printed 11/16/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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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, 3.3V or 5V
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
Power up time, to all clocks stable, 32k running
Power on time,VDD32=0V to all clocks stable
Power on time, all power down pins taken high
MK3235
Handheld System Clock Synthesizer
Minimum
Typical
Maximum
7
VDD+0.5
70
260
150
5.5
5.5
0.8
VDD-0.4
2.4
0.4
1.9
0.4
2.4
0.4
9
3.5
6
2.5
1
±30
±80
7
32.768
Units
V
V
°C
°C
°C
V
V
V
V
V
V
V
V
V
V
V
mA
µA
mA
µA
µA
mA
mA
pF
kHz
ns
%
%
ps
ms
ms
ms
Conditions
Referenced to GND
Referenced to GND
Max of 30 seconds
ABSOLUTE MAXIMUM RATINGS (note 1)
-0.5
0
-65
3.0
2.0
2.0
DC CHARACTERISTICS (at 5.0V unless otherwise noted)
VDD=5V
VDD=5V
IOH=-4mA
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
No Load
No Load
No Load
32kHz output off. PD=0
32kHz output
14, 1.8MHz outputs
AC CHARACTERISTICS (at 5.0V unless otherwise noted)
2
55
500
9
500
15
1000
At VDD/2
45
At VDD32/2
14.318 MHz
-500
VDD=3.3 or 5V
32.768kHz crystal with ESR
≤25kΩ
32.768kHz oscillator running
49 to 51
57
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.
MDS 3235 D
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Revision 092397
Printed 11/16/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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Package Outline and Package Dimensions
MK3235
Handheld 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
MK3235-01S
MK3235-02S
MK3235-01STR
MK3235-02STR
Marking
MK3235-01S
MK3235-02S
MK3235-01S
MK3235-02S
Communications Clock
1.843 MHz
3.686 MHz
1.843 MHz
3.686 MHz
Package
16 pin SOIC
16 pin SOIC
Add Tape & Reel
Add Tape & Reel
Temperature
0-70°C
0-70°C
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.
MDS 3235 D
4
Revision 092397
Printed 11/16/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
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