DS1086L Dallas Semiconductor, DS1086L Datasheet - Page 10

• Manufacturer Part Number: DS1086L
• Description: Spread-Spectrum EconOscillator
• Manufacturer: Dallas Semiconductor

The output frequency is determined by the following
equation:
where: min frequency of selected OFFSET range is the
lowest frequency (shown in
ing offset).
DAC value is the value of the DAC register (0 to 1023).
Prescaler is the value of 2
3.3V Spread-Spectrum EconOscillator
Table
X
X
X
X = Don’t care.
Table
*Factory default setting. OS is the integer value of the five LSBs
of the RANGE register.
10
PRESCALER
PRESCALER
DAC (MSB)
DAC (LSB)
OFFSET
ADDR
RANGE
WRITE EE
0
1
X
f
OUTPUT
REGISTER
= Don’t care, reads as zero.
= Don’t care, reads as one.
= Don’t care, reads indeterminate.
OFFSET
OS + 1
OS + 2
OS + 3
OS + 4
OS + 5
OS + 6
____________________________________________________________________
OS - 6
OS - 5
OS - 4
OS - 3
OS - 2
OS - 1
OS*
1. Register Summary
2. Offset Settings
=
(
MIN FREQUENCY OF SELECTED OFFSET RANGE
ADDR
0Dh
02h
08h
0Eh
37h
3Fh
—
—
+
(
DAC VALUE
FREQUENCY RANGE (MHz)
MSB
JS4
x
P1
b9
b1
X
X
X
1
1
X
where x = 0 to 8.
PRESCALER
Table
× 5
30.7 to 35.8
33.3 to 38.4
35.8 to 41.0
38.4 to 43.5
41.0 to 46.1
43.5 to 48.6
46.1 to 51.2
48.6 to 53.8
51.2 to 56.3
53.8 to 58.9
56.3 to 61.4
58.9 to 64.0
61.4 to 66.6
JS3
P0
b0
X
b8
X
X
kHz STEP SIZE
X
1
1
2 for the correspond-
JS2
X
b7
X
X
X
X
X
0
1
1
X
)
JS1
X
b6
X
b4
X
b4
NO DATA
X
0
1
BINARY
)
JS0
WC
b5
b3
b3
X
X
X
0
See the Example Frequency Calculations section for a
more in-depth look at using the registers.
The DS1086L registers are used to program the output
frequency, dither percent, dither rate, and 2-wire
address. Table 1 shows a summary of the registers and
detailed descriptions follow below.
The PRESCALER word is a two-byte value containing
control bits for the prescaler (P3 to P0), output control
(Lo/HiZ), the jitter rate (JS4 to JS3), as well as control
bits for the jitter percentage (JS2 to JS0). The
PRESCALER word is read and written using two-byte
reads and writes beginning at address 02h.
JS4 to JS3: Jitter Rate. This is the frequency of the tri-
angle wave generator and the modulation frequency
that the output is dithered. It can be programmed to the
master oscillator frequency, f
8192, 4096, or 2048.
LO/HiZ
________________Register Definitions
JS4
b4
b2
A2
b2
X
X
0
0
1
X
0
JS3
P3
X
b3
X
b1
A1
b1
0
1
0
X
0
LSB
P2
X
b2
b0
A0
b0
X
X
0
f
OSC
JITTER RATE
f
f
/4096 (default)
OSC
OSC
01111101b
00000000b
11110000b
FACTORY
0 1 1 0 0 0 0 0
1 1 1 - - - - - b
0 0 X X X X X
x x x - - - - - b
DEFAULT
/8192
/2048
—
OSC
PRESCALER (02h)
, divided by either
ACCESS
R/W
R/W
R/W
R/W
R/W
R/W
—
R