LTC1799
1kHz to 33MHz
Resistor Set SOT-23 Oscillator
FEATURES
s
s
s
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
One External Resistor Sets the Frequency
Fast Start-Up Time: < 1ms
1kHz to 33MHz Frequency Range
Low Profile (1mm) ThinSOT
TM
Package
Frequency Error
≤1.5%
5kHz to 20MHz
(T
A
= 25°C)
Frequency Error
≤
2% 5kHz to 20MHz
(T
A
= 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
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
(R
SET
). The LTC1799 has been designed for high accuracy
operation (≤1.5% frequency error) without the need for
external trim components.
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
R
SET
and frequency, eliminating the need for tables to
calculate frequency. The oscillator can be easily pro-
grammed using the simple formula outlined below:
100, DIV Pin
=
V
+
10k
f
OSC
=
10MHz
•
, N
=
10, DIV Pin
=
Open
N
•
R
SET
1, DIV Pin
=
GND
APPLICATIO S
s
s
s
s
s
s
s
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
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
Typical Distribution of Frequency Error,
T
A
= 25°C (5kHz
≤
f
OSC
≤
20MHz, V
+
= 5V)
25
Basic Connection
5V
0.1µF
3k
≤
R
SET
≤
1M
1
2
3
1kHz
≤
f
OSC
≤
33MHz
5
5V
4
÷100
÷1
÷10
UNITS (%)
20
V
+
OUT
LTC1799
GND
SET
DIV
1799 TA01
15
10
OPEN
5
SOT-23 Actual Size
0
–1.25
–0.75
–0.25 0 0.25
0.75
FREQUENCY ERROR (%)
U
1.25
1799 TA02
U
U
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
