Datasheet

DS1089L
3.3V Center Spread-Spectrum EconOscillator™
_____________________________________________________________________ 7
Block Diagram
FACTORY-
PROGRAMMED
MASTER
OSCILLATOR
33.3MHz TO
66.6MHz
PRESCALER
DIVIDE BY 1, 2, 4,
8, 16, 32, 64,
128, OR 256
TRIANGLE-
WAVE
GENERATOR
I
2
C SERIAL
INTERFACE
PRESCALER
ADDR
P0P1P2P3X
LO/
HIZ
J0J1
A0A1A2WCXOEJ2
J3
V
CC
V
CC
SCL
SDA
DITHER RATE
DITHER %
EEPROM
WRITE EE
COMMAND
OUT
I
2
C
ADDRESS
BITS
PRESCALER SETTING
EEPROM
WRITE
CONTROL
CONTROL REGISTERS
f
MOD
f
OSC
f
MOSC
f
MOSC
f
OUT
SYNCED
OUTPUT
BUFFER
OUTPUT CONFIGURATION
OUTPUT CONTROL
OE
PDN
GND
SPRD
S/W GATED OUTPUT
H/W GATED OUTPUT
DS1089L
Detailed Description
Master Oscillator
The internal master oscillator is capable of generating a
square wave with a 33.3MHz to 66.6MHz frequency
range. The master oscillator frequency (f
MOSC
) is factory
programmed, and is specified in the Ordering Information.
Prescaler
The user can program the prescaler divider to produce
an output frequency (f
OUT
) as low as 130kHz using bits
P0, P1, P2, and P3 in the PRESCALER register. The
output frequency can be calculated using Equation 1.
Any value programmed greater than 2
8
will be decod-
ed as 2
8
. See Table 1 for prescaler divider settings.
Equation 1
where x = P3, P2, P1, P0
Output Frequency Hz f
f
OSC
MOSC
x
() =
2
BITS P3, P2,
P1, P0
2
x
=f
OUT =
f
OSC
0000 1 f
MOSC
0001 2 f
MOSC
/ 2
0010 4 f
MOSC
/ 4
0011 8 f
MOSC
/ 8
0100 16 f
MOSC
/ 16
0101 32 f
MOSC
/ 32
0110 64 f
MOSC
/ 64
0111 128 f
MOSC
/ 128
1000 256 f
MOSC
/ 256
1111 256 f
MOSC
/ 256
Table 1. Prescaler Divider Settings