MK3234 Datasheet, PDF (1/4 Pages) Integrated Circuit Systems – Portable System Clock Synthesizer

I CR O C LOC K
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.
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
X2
Crystal
Oscillator
System
Clock Synthesis
and Control
Circuitry
Output
Buffer
14.318 MHz
Output
Buffer
32.768 kHz
MDS 3234 C
1
Revision 022798
Printed 11/16/00
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