LTC6905C(RevA) Ver la hoja de datos (PDF) - Linear Technology
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LTC6905C Datasheet PDF : 8 Pages
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LTC6905
17MHz to 170MHz
Resistor Set SOT-23 Oscillator
FEATURES
■ One External Resistor Sets the Frequency
■ Fast Start-Up Time: 100µs Typical
■ Frequency Range: 17MHz to 170MHz
■ Frequency Error ±0.5% Typ 17MHz to 170MHz
(TA = 0°C to 70°C, Over All Settings)
■ ±20ppm/°C Temperature Stability
■ Rise Time: 0.5ns, CL = 5pF
■ Timing Jitter: 50ps at 170MHz
■ 50% ±2.5% Duty Cycle
■ 6mA Typical Supply Current, fOSC = 100MHz
■ CMOS Output Drives 500Ω Load (VS = 3V)
■ Operates from a Single 2.7V to 5.5V Supply
■ Low Profile (1mm) ThinSOTTM Package
U
APPLICATIO S
■ High Frequency Precision Oscillator
■ High Speed Data Bus Clock
■ Fixed Crystal Oscillator Replacement
■ Ceramic Oscillator Replacement
, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a
trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents, including 6614313, 6342817.
DESCRIPTIO
The LTC®6905 precision, programmable silicon oscillator
is easy to use and occupies very little board space. It
requires only a single resistor to set the output frequency
from 17MHz to 170MHz with a typical frequency error of
0.5% or less.
The LTC6905 operates with a single 2.7V to 5.5V power
supply and provides a rail-to-rail, 50% duty cycle square
wave output. The CMOS output driver ensures fast rise/fall
times and rail-to-rail switching. Operation is simple: A
single resistor, RSET, between 10K to 25K is used to set the
frequency, and an internal three-state divider (DIV input)
allows for division of the master clock by 1, 2 or 4,
providing three frequencies for each RSET value.
The LTC6905 features a proprietary feedback loop that
linearizes the relationship between RSET and frequency,
eliminating the need for tables to calculate frequency. The
oscillator can be easily programmed using the simple
formula outlined below:
⎧1, DIV Pin = V +
fOSC
=
⎛ 168.5MHz •10kΩ
⎝⎜
RSET
+ 1.5MHz⎞⎠⎟
•
1,
N
N
=
⎨⎪2, DIV
⎩⎪4, DIV
Pin
Pin
=
=
Open
GND
For higher accuracy, fixed frequency versions that include
an internal frequency-setting resistor, see the LTC6905-
XXX Series datasheet.
TYPICAL APPLICATIO
Basic Connection
5V
10k ≤ RSET ≤ 25k
0.1µF
17.225MHz ≤ fOSC ≤ 170MHz
1 V+
5
OUT
LTC6905
2
GND
3
4
SET DIV
5V
÷1
÷2
OPEN
6905 TA01
÷4
Typical Distribution of Frequency Error, TA = 25°C
60 V+ = 3V
RSET = 12k
50 DIV = 1
40
30
20
10
0
–0.5 –0.3
–0.1 0.1
% ERROR
0.3
0.5
6905 TA02
NOTE: RESISTOR, RSET, TOLERANCE WILL ADD
TO THE FREQUENCY ERROR
6905fa
1
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