LTC6990 Datasheet, PDF (1/28 Pages) Linear Technology – TimerBlox: Voltage Controlled Silicon Oscillator

Electrical Specifications Subject to Change
LTC6990
TimerBlox: Voltage
Controlled Silicon Oscillator
FEATURES
n _{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
n _{Frequency Range: 488Hz to 2MHz}
n _{2.25V to 5.5V Single Supply Operation}
n _{72μA Supply Current at 100kHz}
n _{500μs Start-Up Time}
n _{VCO Bandwidth >300kHz at 1MHz}
n _{CMOS Logic Output Sources/Sinks 20mA}
n _{50% Duty Cycle Square Wave Output}
n _{Output Enable (Selectable Low or Hi-Z When Disabled)}
n _{–40°C to 125°C Operating Temperature Range}
n _{Available in Low Profile (1mm) SOT-23 (ThinSOT™)}
and 2mm × 3mm DFN Package
APPLICATIONS
n _{Low Cost Precision Programmable Oscillator}
n _{Voltage-Controlled Oscillator}
n _{High Vibration, High Acceleration Environments}
n _{Replacement for Fixed Crystal and Ceramic Oscillators}
n _{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.
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.
A single resistor, R_SET, programs the LTC6990’s inter-
nal master oscillator frequency. The output frequency
is determined by this master oscillator and an internal
frequency divider, N_DIV, programmable to eight settings
from 1 to 128.
f_OUT
=
1MHz
N_DIV
•
50kΩ
R_SET
,
N_DIV
=
1,
2,
4
…128
Optionally, a second resistor at the SET input provides linear
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.
The LTC6990 includes an enable function that is synchro-
nized with the master oscillator to ensure clean, glitch-free
output pulses. The disabled output can be configured to
be high impedance or forced low.
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
V_CTRL
V⁺
f_OUT
 1MHz V_CTRL
•
0.5
MHz
V
R_VCO
100k
OE
OUT
LTC6990
GND
V⁺
SET
R_SET
100k
DIV
6990 TA01a
V⁺
C1
0.1μF
VCO Transfer Function
1000
750
500
250
0
0
0.5
1
1.5
2
V_CTRL (V)
6990 TA01b
6990p
1