Portable System Clock Synthesizer
Description
I C R O C LOC K
Description
The MK3230 is the smallest size, lowest power system clock synthesizer available.
It is the ideal way to generate clocks for portable computers, PDAs, 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, system, keyboard controller, and floppy (or super I/O) controller output clocks.
The device has two power down modes.
From the CPU decoding table (when FS0, FS1, and FS2 all are low), the CPU and 14.
3 MHz system clocks can be turned off.
Also, the keyboard and 24 MHz peripheral clocks can be shut off from PD24+KBD (pin 10).
The part has a separate VDD32 pin for the 32 kHz clock, allowing it to run at a different voltage (down to 2.
0V) from the rest of the chip, allowing it to run from a back-up battery.
MK3230 Portable System Clock Synthesizer
Features
• Packaged in 16 pin narrow (0.
150”) SOIC • Input crystal frequency of 32.
768 kHz • Lowest power solution available • Lowest profile clock solution where height is critical • Output clock frequencies up to 80 MHz • Five output clocks • 3.
3V or 5.
0V operation • Duty cycle of 45/55 • Seven selectable CPU frequencies • CPU and peripheral clock power downs • Separate battery supply pin for 32 kHz • IDD less than 5µA when 32 kHz running • Available with either 12MHz (-01) or 16MHz (-02) keyboard clock output • 14.
3MHz output is not suitable for driving PLL for CRT.
Will drive all other functions • 32kHz crystals require long startup (>500ms)
Block Diagram
VDD GND
CPUS0 CPUS1 CPUS2 Clock Synthesis and Control Circuitry
Output Buffer Output Buffer Output Buffer Output Buffer
CPUCLK
12 or 16 MHz
PD24+KBD
24.
00 MHz 14.
32 MHz
VDD32
X1
Crystal Oscillator
X2
Output Buffer
32.
768 kHz
32.
768 kHz crystal
MDS 3230 F
1 Revision 022798 Printed 11/16/00 Integrated Circuit Systems, Inc.
•525 Race Street•San Jose•CA•95126•(408)295-9800tel•www.
icst.
com
I C R O C LOC K
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