ICST MK3234-01S, MK3234-01STR Datasheet
MK3234
ICRO
C
LOCK
Description
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.
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
CPUS0
CPUS1
CPUS2
PDCPU
PD
VDD32
32.768 kHz
crystal
X1
X2
VDD GND
Crystal
Oscillator
CPU
Clock Synthesis
and Control
Circuitry
System
Clock Synthesis
and Control
Circuitry
Output
Buffer
Output
Buffer
Output
Buffer
CPUCLK
14.318 MHz
32.768 kHz
MDS 3234 C 1 Revision 022798 Printed 11/16/00
MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•(408)295-9800tel•(408)295-9818fax
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 Assignment
CPUS2
VDD32
VDD
GND
32K
GND
ICRO
X2
X1
C
LOCK
1
2
3
4
5
6
16
15
14
13
12
11
7 10
8 9
CPUS1
CPUS0
CPUCLK
VDD
GND
14.3M
PD
PDCPU
Pin Descriptions
Number Name Type Description
1 CPUS2 I Select 2 for CPUCLK frequencies. See Table above.
2 X2 O Crystal connection. Connect to 32.768 kHz crystal.
3 X1 I Crystal connection. Connect to 32.768 kHz crystal.
4 VDD32 P Separate power supply connection for 32.768kHz clock. Will operate to 2.0V.
5 VDD P Connect to +3.3V or +5V. Must be the same voltage as pin 13.
6 GND P Connect to ground.
7 32K O 32.768 kHz square wave clock output.
8 GND P Connect to ground.
9 PDCPU I Power Down CPU clock output (stops low) when low.
10 PD I Powers Down everything but 32kHz oscillator internally. 32kHz output buffer is off.
11 14.3M O 14.318 MHz clock output. Do not use to drive video CRT controller.
12 GND P Connect to ground.
13 VDD P Connect to +3.3V or +5V. Must be the same voltage as pin 5.
14 CPUCLK O CPUCLK output. See Table above.
15 CPUS0 I Select 0 for CPUCLK frequencies. See Table above.
16 CPUS1 I 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.
MDS 3234 C 2 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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