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參數(shù)資料
| 型號(hào)： | DS1086 |
| 英文描述： | 10/100/1000 Base-T Ethernet LAN Switch |
| 中文描述： | 擴(kuò)頻EconOscillator |
| 文件頁數(shù)： | 11/14頁 |
| 文件大?。?/td> | 229K |
| 代理商： | DS1086 |
D
DS1086 Spread-Spectrum EconOscillator
____________________________________________________________________
11
must be read from the RANGE register (last five bits). In
this example, 12h (18 decimal) was read from the
RANGE register. OS - 2 for this case is 10h (16 deci-
mal). This is the value that is written to the OFFSET reg-
ister.
Finally, the two-byte DAC value needs to be deter-
mined. Since OS - 2 only sets the range of frequencies,
the DAC selects one frequency within that range as
shown in Equation 3.
f
MASTER OSCILLATOR = (MIN FREQUENCY OF SELECTED OFFSET
RANGE) + (DAC value x 10kHz)
Valid values of DAC are 0 to 1023 (decimal) and 10kHz
is the step size. Equation 4 is derived from rearranging
Equation 3 and solving for DAC.
Since the two-byte DAC register is left justified, 655 is
converted to hex (028Fh) and bit-wise shifted left six
places. The value to be programmed into the DAC reg-
ister is A3C0h.
In summary, the DS1086 is programmed as follows:
PRESCALER = 03h (4% peak dither) or 13h (2% peak
dither)
OFFSET = OS - 2 or 10h (if range was read as 12h)
DAC = A3C0h
Notice that the DAC value was rounded. Unfortunately,
this means that some error is introduced. In order to
calculate how much error, a combination of Equation 1
and Equation 3 is used to calculate the expected out-
put frequency. See Equation 5.
The expected output frequency is not exactly equal to the
desired frequency of 11.0592MHz. The difference is
450Hz. In terms of percentage, Equation 6 shows that the
expected error is 0.004%. The expected error assumes
typical values and does not include deviations from the
typical as specified in the electrical tables.
Example #2:
Calculate the register values needed to
generate a desired output frequency of 100MHz.
Since the desired frequency is already within the valid
master oscillator frequency range, the prescaler is set
to divide by 1, and hence, PRESCALER = 00h (for 4%
peak dither) or 10h (for 2% peak dither).
f
MASTER OSCILLATOR
= 100.0MHz x 2
0
= 100.0MHz
Next, looking at
Table
2, OS + 1 provides a range of
frequencies centered around the desired frequency. In
order to determine what value to write to the OFFSET
register, the RANGE register must first be read.
Assuming 12h was read in this example, 13h (OS + 1)
is written to the OFFSET register.
Finally, the DAC value is calculated as shown in
Equation 8.
The result is then converted to hex (0110h) and then
left-shifted, resulting in 4400h to be programmed into
the DAC register.
In summary, the DS1086 is programmed as follows:
PRESCALER = 00h (4% peak dither) or 10h (2% peak
dither)
OFFSET = OS + 1 or 13h (if RANGE was read as 12h)
DAC = 4400h
f
MHz
kHz
MHz
1
MHz
OUTPUT
(
.
) (
2
)
.
.
=
=
=
97 28
272 10
100 0
100 0
0
DAC VALUE
MHz
kHz STEP SIZE
10
MHz
decimal
(
(
.
.
)
.
)
=
=
100 0
97 28
272 00
%
×
%
.
.
.
.
×
.
0 004
%
ERROR
f
f
f
ERROR
MHz
11 0592
MHz
MHz
Hz
MHz
EXPECTED
DESIRED
EXPECTED
DESIRED
EXPECTED
=
=
×
=
=
100
11 0592
11 05875
100
450
11 0592
100
f
MIN FREQUENCY OF SELECTED OFFSET
RANGE
DAC VALUE x
prescaler
MHz
OUTPUT
=
kHz STEP SIZE
10
f
x
kHz
MHz
8
MHz
OUTPUT
(
) (
)
(
.
) (
)
.
.
=
=
=
81 92
655
10
8
88 47
11 05875
DAC VALUE
f
MIN FREQUENCY OF SELECTED
OFFSET RANGE
kHz STEP SIZE
10
DAC VALUE
MHz
kHz STEP SIZE
decimal
(
655
MHz
MASTER OSCILLATOR
(
)
(
.
.
)
.
)
=
=
=
≈
88 4736
10
81 92
655 36
(4)
(8)
(7)
(6)
(5)
(9)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS1086U | DS1086 Spread-Spectrum EconOscillator |
| DS1086Z | DS1086 Spread-Spectrum EconOscillator |
| DS1094L | 10/100/1000 Base-T Ethernet LAN Switch |
| DS1094LU | Multiphase Spread-Spectrum EconOscillator |
| DS1099 | Low-Frequency Dual EconOscillator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS1086_1203 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Spread-Spectrum EconOscillator |
| DS1086HU-C01 | 制造商:Maxim Integrated Products 功能描述:TRW 5V OSC 360 KHZ 8% CTR 8192 8U - Rail/Tube |
| DS1086HU-C01/T | 制造商:Maxim Integrated Products 功能描述:TRW 5V OSC 360 K 8% CTR 8192 8U TRL - Tape and Reel |
| DS1086HU-C02+ | 功能描述:可編程振蕩器 Spread-Spectrum EconOscillator RoHS:否 制造商:IDT 封裝 / 箱體:5 mm x 7 mm x 1.5 mm 頻率:15.476 MHz to 866.67, 975 MHz to 1300 MHz 頻率穩(wěn)定性:+/- 50 PPM 電源電壓:3.63 V 負(fù)載電容:10 pF 端接類型:SMD/SMT 輸出格式:LVPECL 最小工作溫度:- 40 C 最大工作溫度:+ 85 C 尺寸:7 mm W x 5 mm L x 1.5 mm H 封裝: |
| DS1086HU-C02+T | 制造商:Maxim Integrated Products 功能描述:TRW 5V OSC 600KHZ 8 CTR 8196 8U T&R - Tape and Reel |
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