LTC6905
17MHz to 170MHz
Resistor Set SOT-23 Oscillator
FEATURES
DESCRIPTION
The LTC®6905 precision, programmable silicon oscilla-
tor 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.
n
One External Resistor Sets the Frequency
n
Fast Start-Up Time: 100μs Typical
n
Frequency Range: 17MHz to 170MHz
n
Frequency Error 0.5% Typ 17MHz to 170MHz
(T = 0°C to 70°C, Over All Settings)
A
n
20ppm/°C Temperature Stability
The LTC6905 operates with a single 2.7V to 5.5V power
supply and provides a rail-to-rail, 50% duty cycle square
waveoutput.TheCMOSoutputdriverensuresfastrise/fall
times and rail-to-rail switching. Operation is simple: A
n
Rise Time: 0.5ns, C = 5pF
L
n
n
n
n
n
n
Timing Jitter: 7.2ps RMS at 170MHz
50% 2.5% Duty Cycle
6mA Typical Supply Current, f
= 100MHz
S
OSC
single resistor, R , between 10k to 25k is used to set
SET
CMOS Output Drives 500Ω Load (V = 3V)
the frequency, and an internal three-state divider (DIV
Operates from a Single 2.7V to 5.5V Supply
input) allows for division of the master clock by 1, 2 or 4,
™
Low Profile (1mm) ThinSOT Package
providing three frequencies for each R value.
SET
The LTC6905 features a proprietary feedback loop that
APPLICATIONS
linearizes the relationship between R
and frequency,
SET
eliminating the need for tables to calculate frequency. The
oscillator can be easily programmed using the simple
formula outlined below:
n
High Frequency Precision Oscillator
n
High Speed Data Bus Clock
n
Fixed Crystal Oscillator Replacement
Ceramic Oscillator Replacement
n
1, DIV Pin = V+
⎧
⎪
⎛168.5MHz •10kΩ
⎞
1
⎠ N
L, LT, LTC and LTM 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.
fOSC
=
+ 1.5MHz • , N = 2, DIV Pin = Open
⎜
⎟
⎨
⎝
RSET
⎪
4,DIV Pin = GND
⎩
For higher accuracy, fixed frequency versions that
include an internal frequency-setting resistor, see the
LTC6905-XXX Series data sheet
.
TYPICAL APPLICATION
Typcial Distribution of Frequency Error, TA = 25°C
60
+
V
R
= 3V
= 12k
SET
50
DIV = 1
Basic Connection
40
30
17.225MHz ≤ f
5
≤ 170MHz
OSC
5V
1
2
3
+
V
OUT
LTC6905
0.1μF
5V
10k ≤ R
≤ 25k
20
10
0
SET
GND
SET
÷1
÷4
4
÷2
DIV
OPEN
6905 TA01
–0.5
–0.3
–0.1
0.1
0.3
0.5
6905 TA02
% ERROR
NOTE: RESISTOR, R , TOLERANCE WILL ADD
SET
TO THE FREQUENCY ERROR
6905fd
1