Datasheet MK3234-01S, MK3234-01STR Datasheet (ICST)

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•[phone]tel•[phone]fax

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•[phone]tel•[phone]fax

MK3234

ABSOLUTE MAXIMUM RATINGS (note 1)

DC CHARACTERISTICS (at 5.0V unless otherwise noted)

AC CHARACTERISTICS (at 5.0V unless otherwise noted)

32.768kHz crystal with ESR ≤25kΩ

32.768kHz oscillator running

ICRO

C

LOCK

Portable System Clock Synthesizer

Electrical Specifications

Parameter Conditions Minimum Typical Maximum Units

Supply Voltage, VDD Referenced to GND 7 V
Inputs and Clock Outputs Referenced to GND -0.5 VDD+0.5 V
Ambient Operating Temperature 0 70 °C
Soldering Temperature Max of 30 seconds 260 °C
Storage Temperature -65 150 °C

Operating Voltage, VDD 3.0 5.5 V
Operating Voltage,VDD32 2.0 5.5 V
Input High Voltage, VIH VDD=5V 2.0 V
Input Low Voltage, VIL VDD=5V 0.8 V
Output High Voltage, VOH VDD=5V, IOH=-25mA 2.4 V
Output Low Voltage, VOL VDD=5V, IOL=25mA 0.4 V
Input High Voltage, VIH VDD=3.3V 1.9 V
Input Low Voltage, VIL VDD=3.3V 0.4 V
Output High Voltage, VOH VDD=3.3V, IOH=-8mA 2.4 V
Output Low Voltage, VOL VDD=3.3V, IOL=8mA 0.4 V
IDD Operating Supply Current, 5V No Load, 50MHz 15 mA
IDD32 with only 32 kHz running, 5V No Load 3.5 µA
IDD Operating Supply Current, 3.3V No Load, 50MHz 9 mA
IDD32 with only 32 kHz output running, 3.3V No Load 2.5 µA
IDD32, only 32 kHz osc. running, 3.3V, note 2 32kHz output off. PD=0 1 µA
Short Circuit Current, 5V 32 kHz output ±30 mA
Short Circuit Current, 5V CPU output ±100 mA
Input Capacitance 7 pF

Input Frequency 32.768 kHz
Output Clock Rise and Fall Time, 0.2 to 0.8VDD 2 ns
Output Clock Duty Cycle, all MHz clocks At VDD/2 45 49 to 51 55 %

32.768 kHz Clock Duty Cycle At VDD32/2 57 %
Absolute Clock Period Jitter, CPU clock 20 to 50 MHz -500 500 ps
Power up time, CPU off to 50 MHz, 32k running VDD=3.3 or 5V 9 ms
Transition time, 8 MHz to 50 MHz VDD=3.3 or 5V 4 ms
Transition time, 50 MHz to 8 MHz VDD=3.3 or 5V 2.5 ms
Power on time,VDD32=0V to all clocks stable
Power on time, all power down pins taken high

Note 1: Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged
exposure to levels above the operating limits but below the Absolute Maximums may affect device reliability.
Note 2: When PD=0 (low) and VDD32 is greater than 2.0V, then the 32kHz oscillator will continue to run on the chip, but the
output is turned off. This allows for a quick power-up (<20ms), while the chip is only consuming approximately 1µA.

MDS 3234 C 3 Revision 022798 Printed 11/16/00

MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•[phone]tel•[phone]fax

500 1000 ms

15 ms

MK3234

Inches

Millimeters

ICRO

C

LOCK

Package Outline and Package Dimensions

E H

h x 45°

D

Q

e

b

c

Portable System Clock Synthesizer

16 pin SOIC narrow

Symbol Min Max Min Max

A 0.055 0.068 1.397 1.7272
b 0.013 0.019 0.330 0.483

c 0.007 0.010 0.191 0.254

D 0.385 0.400 9.779 10.160

E 0.150 0.160 3.810 4.064

H 0.225 0.245 5.715 6.223

e

h 0.016 0.406

Q 0.004 0.01 0.102 0.254

A

Ordering Information

Part/Order Number Marking Package Temperature

MK3234-01S MK3234-01S 16 pin SOIC 0-70°C

MK3234-01STR MK3234-01S Add Tape & Reel 0-70°C

While the information presented herein has been checked for both accuracy and reliability, MicroClock Incorporated assumes no responsibility for either its use or for the
infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in
normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements
are not recommended without additional processing by MicroClock. MicroClock reserves the right to change any circuitry or specifications without notice. MicroClock does not
authorize or warrant any MicroClock product for use in life support devices or critical medical instruments.

MDS 3234 C 4 Revision 022798 Printed 11/16/00

MicroClock Division of ICS•1271 Parkmoor Ave.•San Jose•CA•95126•[phone]tel•[phone]fax