MK3235
Handheld System Clock Synthesizer
ICR O CLOC K
Pin Assignment
1
16 GND
X2
15
14
13
12
11
10
9
X1
VDD32
VDD
2
3
GND
VDD
4
5
PD14
GND
14.3M
GND
6
7
COMMCLK
32K
PD
8
GND
PDCOMM
Pin Descriptions
Number
Name
Type Description
1
2
X2
O
I
Crystal connection. Connect to 32.768 kHz crystal.
Crystal connection. Connect to 32.768 kHz crystal.
X1
3
VDD32
VDD
P
P
P
O
O
I
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.
4
5
GND
6
COMMCLK
32K
Serial communications (1.84 on -01 version, or 3.68MHz on -02 version) clock output.
32.768 kHz square wave clock output.
7
8
PDCOMM
GND
Power Down serial Communications and 14.3M clock outputs (stop low) when low.
Connect to ground.
9
P
I
10
11
12
13
14
15
16
PD
Powers Down everything but 32kHz oscillator internally. 32kHz output buffer is off.
14.318 MHz output clock.
14.3M
GND
O
P
I
Connect to ground.
PD14
VDD
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.
P
P
P
GND
GND
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
33Wmay 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