Low-Frequency Dual EconOscillator
Functional Diagram
DS1099
V
CC
V
CC
MASTER
OSCILLATOR
1.048MHz
f
MOSC
DIVIDER 0
DIVIDE BY 2
X
(X = X
0
= 0...22)
OUTPUT
DRIVER
f
OUT0
DS1099
GND
OUT0
FACTORY-
PROGRAMMED
EEPROM
DIVIDER 1
DIVIDE BY 2
X
(X = X
1
= 0...22)
OUTPUT
DRIVER
f
OUT1
OUT1
OE0
OE1
Detailed Description
The DS1099 consists of a fixed-frequency 1.048MHz
master oscillator followed by two independent factory-
programmable dividers. The two divider outputs are
connected to pins OUT0 and OUT1, which are inde-
Table 1. Divider Settings and Output
Frequencies
DIVIDER SETTING
X
0
OR X
1
0
1
2
3
4
5
—
19
20
21
22
DIVISOR
1
2
4
8
16
32
—
524,288
1,048,576
2,097,152
4,194,304
f
OUT0
OR f
OUT1
1.048MHz
0.524MHz
0.262MHz
0.131MHz
65.50kHz
32.75kHz
—
2Hz
1Hz
0.5Hz
0.25Hz
pendently enabled/disabled using the output-enable
pins,
OE0
and
OE1,
respectively. When the output-
enable pins are active (low), the corresponding outputs
are enabled. If either output-enable pin is tied to its
inactive state (high), then the corresponding output is
disabled and forced high immediately. The output-
enable pins only disable the corresponding output
driver(s) and do not shut down the master oscillator or
the dividers.
Since the master oscillator frequency, f
MOSC
, is fixed,
the frequency of OUT0 and OUT1 is determined by
DIVIDER 0 and DIVIDER 1, respectively. And since
each output has its own divider, f
OUT0
and f
OUT1
can
be programmed independent of each other.
The frequency of the outputs are calculated as follows:
f
OUT0
= f
MOSC
/ 2
X0
= 1.048MHz / 2
X0
f
OUT1
= f
MOSC
/ 2
X1
= 1.048MHz / 2
X1
where X
0
is the DIVIDER 0 setting and X
1
is the
DIVIDER 1 setting. Valid values for X
0
and X
1
are inte-
gers 0 to 22 (dec).
Table 1 shows output frequencies and divider values
for the range of divider settings.
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5
DALLAS [ DALLAS SEMICONDUCTOR ]
