ICST MK3235-02STR, MK3235-01S, MK3235-01STR, MK3235-02S Datasheet
MK3235
ICRO
C
LOCK
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.
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
PD14
PDCOMM
PD
VDD32
32.768 kHz
crystal
X1
X2
VDD GND
Crystal
Oscillator
14.318MHz
Clock Synthesis
and Control
Circuitry
Communications
Clock Synthesis
and Control
Circuitry
Output
Buffer
Output
Buffer
Output
Buffer
14.3 MHz
1.843 or
3.686 MHz
32.768 kHz
MDS 3235 D 1 Revision 092397 Printed 11/16/00
Integrated Circuit Systems, Inc.•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.icst.com
MK3235
ICRO
C
LOCK
Handheld System Clock Synthesizer
Pin Assignment
X2
X1
VDD32
VDD
GND
COMMCLK
32K
PDCOMM
1
2
3
4
5
6
7 10
8 9
16
15
14
13
12
11
GND
GND
VDD
PD14
GND
14.3M
PD
GND
Pin Descriptions
Number Name Type Description
1 X2 O Crystal connection. Connect to 32.768 kHz crystal.
2 X1 I Crystal connection. Connect to 32.768 kHz crystal.
3 VDD32 P Separate power supply connection for 32.768kHz clock. Will operate to 2.0V.
4 VDD P Connect to +3.3V or +5V. Must be the same voltage as pin 14.
5 GND P Connect to ground.
6 COMMCLK O Serial communications (1.84 on -01 version, or 3.68MHz on -02 version) clock output.
7 32K O 32.768 kHz square wave clock output.
8 PDCOMM I Power Down serial Communications and 14.3M clock outputs (stop low) when low.
9 GND P Connect to ground.
10 PD I Powers Down everything but 32kHz oscillator internally. 32kHz output buffer is off.
11 14.3M O 14.318 MHz output clock.
12 GND P Connect to ground.
13 PD14 I Power Down 14.318MHz clock output (stops low) when low.
14 VDD P Connect to +3.3V or +5V. Must be the same voltage as pin 4.
15 GND P Connect to ground.
16 GND P 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 2 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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