LTC6990
TimerBlox: Voltage
Controlled Silicon Oscillator
FEATURES
DESCRIPTION
The LTC®6990 is a precision silicon oscillator with a pro-
grammable frequency range of 488Hz to 2MHz. It can be
used as a fixed-frequency or voltage-controlled oscillator
(VCO). The LTC6990 is part of the TimerBlox™ family of
versatile silicon timing devices.
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Fixed-Frequency or Voltage-Controlled Operation
– Fixed: Single Resistor Programs Frequency
with <2.2% Max Error
– VCO: Two Resistors Set VCO Center
Frequency and Tuning Range
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Frequency Range: 488Hz to 2MHz
A single resistor, R , programs the LTC6990’s inter-
SET
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2.25V to 5.5V Single Supply Operation
nal master oscillator frequency. The output frequency
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72μA Supply Current at 100kHz
is determined by this master oscillator and an internal
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500μs Start-Up Time
frequency divider, N , programmable to eight settings
DIV
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VCO Bandwidth >300kHz at 1MHz
from 1 to 128.
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CMOS Logic Output Sources/Sinks 20mA
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50% Duty Cycle Square Wave Output
1MHz 50kΩ
NDIV RSET
fOUT
=
•
,NDIV = 1, 2, 4 …128
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Output Enable (Selectable Low or Hi-Z When Disabled)
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–40°C to 125°C Operating Temperature Range
Optionally,asecondresistorattheSETinputprovideslinear
voltage control of the output frequency and can be used
for frequency modulation. A narrow or wide VCO tuning
range can be configured by the appropriate selection of
the two resistors.
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Available in Low Profile (1mm) SOT-23 (ThinSOT™)
and 2mm × 3mm DFN Package
APPLICATIONS
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Low Cost Precision Programmable Oscillator
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Voltage-Controlled Oscillator
The LTC6990 includes an enable function that is synchro-
nizedwiththemasteroscillatortoensureclean,glitch-free
output pulses. The disabled output can be configured to
be high impedance or forced low.
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High Vibration, High Acceleration Environments
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Replacement for Fixed Crystal and Ceramic Oscillators
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Portable and Battery-Powered Equipment
L, LT, LTC and LTM, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. TimerBlox and ThinSOT are trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners. Protected by U.S.
Patents including 6342817, 6614313.
The LTC6990 is available in the 6-lead SOT-23 (ThinSOT)
package or a 6-lead 2mm × 3mm DFN.
TYPICAL APPLICATION
Voltage Controlled Oscillator with 16:1 Frequency Range
VCO Transfer Function
1000
MHz
V
f
ꢀ 1MHz ꢁ V • 0.5
CTRL
+
OUT
V
750
500
250
0
OE
OUT
LTC6990
+
V
+
GND
V
C1
0.1μF
R
VCO
100k
V
SET
DIV
CTRL
6990 TA01a
R
SET
100k
0
0.5
1
1.5
2
V
CTRL
(V)
6990 TA01b
6990f
1