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PDF LTC1799IS5 Data sheet ( Hoja de datos )
| Número de pieza | LTC1799IS5 | |
| Descripción | 1kHz to 33MHz Resistor Set SOT-23 Oscillator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC1799
1kHz to 33MHz
Resistor Set SOT-23 Oscillator
FEATURES
s One External Resistor Sets the Frequency
s Fast Start-Up Time: < 1ms
s 1kHz to 33MHz Frequency Range
s Low Profile (1mm) ThinSOTTM Package
s Frequency Error ≤1.5% 5kHz to 20MHz
(TA = 25°C)
s Frequency Error ≤ 2% 5kHz to 20MHz
(TA = 0°C to 70°C)
s ±40ppm/°C Temperature Stability
s 0.05%/V Supply Stability
s 50% ±1% Duty Cycle 1kHz to 2MHz
s 50% ±5% Duty Cycle 2MHz to 20MHz
s 1mA Typical Supply Current
s 100Ω CMOS Output Driver
s Operates from a Single 2.7V to 5.5V Supply
U
APPLICATIO S
s Low Cost Precision Oscillator
s Charge Pump Driver
s Switching Power Supply Clock Reference
s Clocking Switched Capacitor Filters
s Fixed Crystal Oscillator Replacement
s Ceramic Oscillator Replacement
s Small Footprint Replacement for Econ Oscillators
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
DESCRIPTIO
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.
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 pro-
grammed using the simple formula outlined below:
100, DIV Pin = V +
fOSC
=
10MHz
•
N
10k
• RSET
,
N
=
10,
1,
DIV Pin = Open
DIV Pin = GND
TYPICAL APPLICATIO
Basic Connection
5V
3k ≤ RSET ≤ 1M
0.1µF
1 V+
1kHz ≤ fOSC ≤ 33MHz
5
OUT
2 LTC1799
GND
34
SET DIV
5V
÷100
÷10
OPEN
1799 TA01
÷1
SOT-23 Actual Size
Typical Distribution of Frequency Error,
TA = 25°C (5kHz ≤ fOSC ≤ 20MHz, V+ = 5V)
25
20
15
10
5
0
–1.25
–0.75 –0.25 0 0.25 0.75
FREQUENCY ERROR (%)
1.25
1799 TA02
1
1 page  
LTC1799
PI FU CTIO S
V+ (Pin 1): Voltage Supply (2.7V ≤ V+ ≤ 5.5V). This supply
must be kept free from noise and ripple. It should be
bypassed directly to a ground plane with a 0.1µF capacitor.
GND (Pin 2): Ground. Should be tied to a ground plane for
best performance.
SET (Pin 3): Frequency-Setting Resistor Input. The value
of the resistor connected between this pin and V+ deter-
mines the oscillator frequency. The voltage on this pin is
held by the LTC1799 to approximately 1.13V below the V+
voltage. For best performance, use a precision metal film
resistor with a value between 10k and 200k and limit the
capacitance on this pin to less than 10pF.
DIV (Pin 4): Divider-Setting Input. This three-state input
selects among three divider settings, determining the
value of N in the frequency equation. Pin 4 should be tied
to GND for the ÷1 setting, the highest frequency range.
Floating Pin 4 divides the master oscillator by 10. Pin 4
should be tied to V+ for the ÷100 setting, the lowest
frequency range. To detect a floating DIV pin, the LTC1799
attempts to pull the pin toward midsupply. This is realized
with two internal current sources, one tied to V+ and Pin
4 and the other one tied to ground and Pin 4. Therefore,
driving the DIV pin high requires sourcing approximately
5µA. Likewise, driving DIV low requires sinking 5µA.
When Pin 4 is floated, preferably it should be bypassed by
a 1nF capacitor to ground or it should be surrounded by a
ground shield to prevent excessive coupling from other
PCB traces.
OUT (Pin 5): Oscillator Output. This pin can drive 5kΩ
and/or 10pF loads. Larger loads may cause inaccuracies
due to supply bounce at high frequencies. Transients will
not cause latchup if the current into/out of the OUT pin is
limited to 50mA.
BLOCK DIAGRA
V+
1
RSET
IRES SET
3
+– VBIAS
VRES(V=+1–.1V3SVET±)25%
+
GAIN = 1
–
MASTER OSCILLATOR
ƒMO
=
100MHz
•
kΩ
•
(V+
IRES
– VSET)
2 GND
IRES
PROGRAMMABLE
DIVIDER
(÷1, 10 OR 100)
DIVIDER
SELECT
OUT
5
V+
5µA
THREE-STATE
INPUT DETECT
DIV
4
5µA
GND
1799 BD
5
5 Page 
PACKAGE DESCRIPTIO
S5 Package
5-Lead Plastic SOT-23
(Reference LTC DWG # 05-08-1633)
(Reference LTC DWG # 05-08-1635)
SOT-23
(Original)
A
.90 – 1.45
(.035 – .057)
.00 – .15
A1 (.00 – .006)
A2
.90 – 1.30
(.035 – .051)
L
.35 – .55
(.014 – .021)
SOT-23
(ThinSOT)
1.00 MAX
(.039 MAX)
.01 – .10
(.0004 – .004)
.80 – .90
(.031 – .035)
.30 – .50 REF
(.012 – .019 REF)
.20
(.008)
DATUM ‘A’
2.60 – 3.00
(.102 – .118)
1.50 – 1.75
(.059 – .069)
(NOTE 3)
PIN ONE
.95
(.037)
REF
A A2
L
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2.
DIMENSIONS
ARE
IN
MILLIMETERS
(INCHES)
.09 – .20
(.004 – .008)
(NOTE 2)
3. DRAWING NOT TO SCALE
4. DIMENSIONS ARE INCLUSIVE OF PLATING
5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
6. MOLD FLASH SHALL NOT EXCEED .254mm
7. PACKAGE EIAJ REFERENCE IS:
SC-74A (EIAJ) FOR ORIGINAL
JEDEL MO-193 FOR THIN
2.80 – 3.10
(.110 – .118)
(NOTE 3)
1.90
(.074)
REF
LTC1799
.25 – .50
(.010 – .020)
(5PLCS, NOTE 2)
A1
S5 SOT-23 0401
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1799IS5.PDF ] | |
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