LTC1799
1kHz to 33MHz
Resistor Set SOT-23 Oscillator
Features
Description
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The LTC®1799 is a precision oscillator that is easy to use
and occupies very little PC board space. The oscillator
frequency is programmed by a single external resistor
(RSET). The LTC1799 has been designed for high accuracy
operation (≤1.5% frequency error) without the need for
external trim components.
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One External Resistor Sets the Frequency
Fast Start-Up Time: <1ms
1kHz to 33MHz Frequency Range
Frequency Error ≤1.5% 5kHz to 20MHz
(TA = 25°C)
Frequency Error ≤2% 5kHz to 20MHz
(TA = 0°C to 70°C)
±40ppm/°C Temperature Stability
0.05%/V Supply Stability
50% ±1% Duty Cycle 1kHz to 2MHz
50% ±5% Duty Cycle 2MHz to 20MHz
1mA Typical Supply Current
100Ω CMOS Output Driver
Operates from a Single 2.7V to 5.5V Supply
Low Profile (1mm) SOT-23 (ThinSOT™ Package)
Applications
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Low Cost Precision Oscillator
Charge Pump Driver
Switching Power Supply Clock Reference
Clocking Switched Capacitor Filters
Fixed Crystal Oscillator Replacement
Ceramic Oscillator Replacement
Small Footprint Replacement for Econ Oscillators
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents including 6342817 and 6614313.
The LTC1799 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. The frequency-setting
resistor can vary from 3k to 1M to select a master oscillator frequency between 100kHz and 33MHz (5V supply).
The three-state DIV input determines whether the master
clock is divided by 1, 10 or 100 before driving the output, providing three frequency ranges spanning 1kHz to
33MHz (5V supply). The LTC1799 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:
100, DIV Pin = V +
10k
fOSC = 10MHz •
, N = 10, DIV Pin = Open
N • RSET
1,
DIV Pin = GND
Typical Distribution of Frequency Error,
TA = 25°C (5kHz ≤ fOSC ≤ 20MHz, V + = 5V)
Typical Application
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Basic Connection
1
0.1µF
3k ≤ RSET ≤ 1M
2
3
V+
OUT
LTC1799
5V
GND
SET
DIV
1799 TA01
TSOT-23 Actual Size
20
1kHz ≤ fOSC ≤ 33MHz
5
4
÷100
÷1
÷10
OPEN
UNITS (%)
5V
15
10
5
0
–1.25
–0.75
–0.25 0 0.25
0.75
FREQUENCY ERROR (%)
1.25
1799 TA02
1799fc
1
