LTC6905_15 Datasheet, PDF (1/12 Pages) Linear Technology – 17MHz to 170MHz Resistor Set SOT-23 Oscillator

FEATURES
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_A = 0°C to 70°C, Over All Settings)
n _{±20ppm/°C Temperature Stability}
n _{Rise Time: 0.5ns, CL = 5pF}
n _{Timing Jitter: 7.2ps RMS at 170MHz}
n _{50% ±2.5% Duty Cycle}
n _{6mA Typical Supply Current, fOSC = 100MHz}
n _{CMOS Output Drives 500Ω Load (VS = 3V)}
n _{Operates from a Single 2.7V to 5.5V Supply}
n _{Low Profile (1mm) ThinSOT™ Package}
APPLICATIONS
n _{High Frequency Precision Oscillator}
n _{High Speed Data Bus Clock}
n _{Fixed Crystal Oscillator Replacement}
n _{Ceramic Oscillator Replacement}
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.
LTC6905
17MHz to 170MHz
Resistor Set SOT-23 Oscillator
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.
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, R_SET, 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 R_SET value.
The LTC6905 features a proprietary feedback loop that
linearizes the relationship between R_SET 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 ⁺
f_OSC
=
⎛ 168.5MHz •10kΩ
⎝⎜
R_SET
+
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 data sheet.
TYPICAL APPLICATION
Basic Connection
5V
10k ≤ R_SET ≤ 25k
0.1μF
17.225MHz ≤ f_OSC ≤ 170MHz
1 _V+
5
OUT
2 ^LTC6905
GND
3
4
SET DIV
5V
÷1
÷2
OPEN
6905 TA01
÷4
Typcial Distribution of Frequency Error, T_A = 25°C
60 _{V+ = 3V}
R_SET = 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, R_SET, TOLERANCE WILL ADD
TO THE FREQUENCY ERROR
6905fd
1