LTC1799IS5#TRPBF [Linear]
LTC1799 - 1kHz to 33MHz Resistor Set SOT-23 Oscillator; Package: SOT; Pins: 5; Temperature Range: -40°C to 85°C;型号: | LTC1799IS5#TRPBF |
厂家: | Linear |
描述: | LTC1799 - 1kHz to 33MHz Resistor Set SOT-23 Oscillator; Package: SOT; Pins: 5; Temperature Range: -40°C to 85°C 振荡器 模拟IC 信号电路 光电二极管 |
文件: | 总4页 (文件大小:122K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
Final Electrical Specifications
LTC1799
1kHz to 30MHz
Resistor Set SOT-23 Oscillator
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January 2001
DESCRIPTIO
FEATURES
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). TheLTC1799hasbeendesignedforhighaccuracy
operation (≤1.5% frequency error) without the need for
external trim components.
■
One External Resistor Sets the Frequency
■
1kHz to 30MHz Frequency Range
■
SOT-23 Miniature Package
■
Frequency Error ≤1.5% 5kHz to 20MHz
(TA = 25°C)
■
Frequency Error ≤2% 5kHz to 20MHz
(TA = 0°C to 70°C)
The LTC1799 operates with a single 2.7V to 5.5V power
supply and provides a rail-to-rail, 50% duty cycle square
waveoutput.TheCMOSoutputdriverensuresfastrise/fall
times and rail-to-rail switching. The frequency-setting
resistor can vary from 3.32k to 1M to select a master
oscillator frequency between 100kHz and 30MHz (5V
supply). Thethree-stateDIVinputdetermineswhetherthe
master clock is divided by 1, 10 or 100 before driving the
output, providing three frequency ranges spanning 1kHz
to30MHz(5Vsupply).TheLTC1799featuresaproprietary
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:
■
±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
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APPLICATIO S
■
Low Cost Precision Oscillator
■
Charge Pump Driver
■
Switching Power Supply Clock Reference
■
Clocking Switched Capacitor Filters
100,DIV PIN = V+
■
Fixed Crystal Oscillator Replacement
■
10k
N• RSET
Ceramic Oscillator Replacement
fOSC = 10MHz •
, N = 10, DIV PIN = Hi- Z
1, DIV PIN = GND
■
Small Footprint Replacement for Econ Oscillators
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
Typical Distribution of Frequency Error, TA = 25°C
25
Basic Connection
20
15
10
5
5kHz ≤ f
5
≤ 20MHz
+
OSC
V
1
2
3
V+
LTC1799
OUT
0.1µF
+
V
5k ≤ R
≤ 200k
SET
GND
÷100
÷10
÷10
4
SET
DIV
Hi-Z
1799 TA01
GND
0
SOT-23 Actual Size
–1.25 –0.75
–0.25 0 0.25
0.75
1.25
FREQUENCY ERROR (%)
1799 TA02
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-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
1
LTC1799
W W
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ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
ORDER PART NUMBER
Supply Voltage (V+) to GND ........................–0.3V to 6V
DIV to GND .................................... –0.3V to (V+ + 0.3V)
SET to GND ................................... –0.3V to (V+ + 0.3V)
OUT to GND ................................... –0.3V to (V+ + 0.3V)
Operating Temperature Range
+
V
1
2
3
5
4
OUT
DIV
LTC1799CS5
LTC1799IS5
GND
SET
S5 PACKAGE
5-LEAD PLASTIC SOT-23
S5 PART MARKING
LTC1799C ............................................... 0°C to 70°C
LTC1799I............................................ –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
LTND
LTNE
TJMAX = 125°C, θJA = 256°C/W
Consult factory for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. V+ = 2.7V to 5.5V, RL=5k, CL = 5pF, Pin 4 = V+ unless otherwise noted.
All voltages are with respect to GND.
SYMBOL PARAMETER
∆f Frequency Accuracy
CONDITIONS
MIN
TYP
MAX
UNITS
+
V = 5V
5kHz < f < 20MHz
±0.5
±1.5
±2
±2.5
%
%
%
%
%
5kHz < f < 20MHz, LTC1799C
5kHz < f < 20MHz, LTC1799I
1kHz < f < 5kHz
●
●
(Notes 2, 3)
±2.5
±2.5
20MHz < f < 30MHz
+
V = 3V
5kHz < f < 10MHz
±0.5
±1.5
±2
±2.5
%
%
%
%
%
5kHz < f < 10MHz, LTC1799C
5kHz < f < 10MHz, LTC1799I
1kHz < f < 5kHz
●
●
±2.5
±2.5
10MHz < f < 20MHz
+
R
Frequency-Setting Resistor Range
Maximum Frequency
∆f < 1.5%
V = 5V
5
10
200
200
kΩ
kΩ
SET
MAX
MIN
+
V = 3V
+
f
∆f < 2.5%, Pin 4= 0V
V = 5V
30
20
MHz
MHz
+
V = 3V
+
f
Minimum Frequency
∆f < 2.5%, Pin 4= V
1
kHz
%/°C
%/V
∆f/∆T
∆f/∆V
Freq Drift Over Temp (Note 3)
Freq Drift Over Supply (Note 3)
R
SET
= 31.6k
●
●
±0.004
0.05
+
V = 2.7V to 5.5V, R = 31.6k
0.1
SET
+
Timing Jitter
(Note 4)
Pin 4 = V
0.06
0.13
0.4
%
%
%
Pin 4 = Floating
Pin 4 = 0V
Long-Term Stability of Output Frequency
Duty Cycle
300
ppm/√kHr
+
Pin 4 = V or Floating (DIV Either by 100 or 10)
Pin 4 = 0V (DIV by 1)
●
●
49
45
50
50
51
55
%
%
+
V
Operating Supply Range
Power Supply Current
●
●
2.7
5.5
1.1
V
+
+
I
R
R
= 200k, Pin 4 = V , R = 0
V = 5V
0.7
mA
S
SET
L
+
= 10k, Pin 4 = 0V, No Load
V = 5V
●
●
2.4
2
mA
mA
SET
+
V = 3V
+
V
V
High Level DIV Input Voltage
Low Level DIV Input Voltage
DIV Input Current
●
●
V – 0.4
V
V
IH
IL
0.5
+
I
Pin 4 = V
●
●
5
–5
8
8
µA
µA
DIV
Pin 4 = 0V
2
LTC1799
ELECTRICAL CHARACTERISTICS
All voltages are with respect to GND.
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. V+ = 2.7V to 5.5V, RL=5k, CL = 5pF, Pin 4 = V+ unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
4.8
4.5
TYP
4.95
4.8
MAX
UNITS
+
V
V
High Level Output Voltage
Low Level Output Voltage
V = 5V
I
I
= –1mA
= –4mA
●
●
V
V
OH
OH
OH
+
V = 3V
I
I
= –1mA
= –4mA
●
●
2.7
2.2
2.9
2.6
V
V
OH
OH
+
V = 5V
I
I
= 1mA
= 4mA
●
●
0.05
0.2
0.15
0.4
V
V
OL
OL
OL
+
V = 3V
I
I
= 1mA
= 4mA
+
●
●
0.1
0.4
0.3
0.7
V
V
OL
OL
+
t
t
OUT Rise Time
(Note 5)
V = 5V
Pin 4 = V or Floating, R = 0
Pin 4 = 0V, R = 0
14
7
ns
ns
r
f
L
L
+
+
V = 3V
Pin 4 = V or Floating, R = 0
19
11
ns
ns
L
Pin 4 = 0V, R = 0
L
+
+
OUT Fall Time
(Note 5)
V = 5V
Pin 4 = V or Floating, R = 0
13
6
ns
ns
L
Pin 4 = 0V, R = 0
L
+
+
V = 3V
Pin 4 = V or Floating, R = 0
19
10
ns
ns
L
Pin 4 = 0V, R = 0
L
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: Frequencies near 100kHz and 1MHz may be generated using two
Note 4: Jitter is the ratio of the peak-to-peak distribution of the period to
the mean of the period. This specification is based on characterization and
is not 100% tested.
different values of R (see the Table 1 in the Applications Information
section). For these frequencies, the error is specified under the following
Note 5: Output rise and fall times are measured between the 10% and
90% power supply levels. These specifications are based on
characterization.
SET
assumption: 10k < R ≤ 100k.
SET
Note 3: Frequency error (defined as the deviation from the f
equation)
OSC
includes drift over temperature and over supply.
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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.
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
frequencyrange. TodetectafloatingDIVpin, theLTC1799
attempts to pull the pin toward midsupply. Therefore,
driving the DIV pin high requires sourcing approximately
5µA. Likewise, driving DIV low requires sinking 5µA.
When floated, the DIV pin will be held near midsupply by
these current sources. When it is floated, it is recom-
mended that the DIV pin be bypassed by a 1nF capacitor
or surrounded by a ground shield to prevent excessive
coupling from other PCB traces.
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 1.1V 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 2pF.
OUT (Pin 5): Oscillator Output. This pin can easily drive
5kΩ or 10pF loads. Larger loads may cause inaccuracies
due to supply bounce at high frequencies.
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
3
LTC1799
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APPLICATIO S I FOR ATIO
Table 1. Frequency Range vs Divider Setting
DIVIDER SETTING FREQUENCY RANGE
Selecting the Divider Setting and Resistor
The LTC1799’s master oscillator has a frequency range
spanning 0.1MHz to 30MHz. However, accuracy may
suffer if the master oscillator is operated at greater than
10MHz with a supply voltage lower than 4V. A program-
mable divider extends the frequency range to greater than
three decades. Table 1 describes the recommended fre-
quencies for each divider setting. Note that the ranges
overlap;atsomefrequenciestherearetwodivider/resistor
combinations that result in the desired frequency.
*
÷1
DIV (Pin 4) = GND
>500kHz
÷10
DIV (Pin 4) = Floating
50kHz to 1MHz
< 100kHz
+
÷100
DIV (Pin 4) = V
*
At master oscillator frequencies greater than 10MHz (R < 10kΩ), the
SET
LTC1799 may suffer reduced accuracy with a supply voltage less than 4V.
After choosing the proper divider setting, determine the
correct frequency-setting resistor. Because of the linear
correspondence between oscillation period and resis-
tance,asimpleequationrelatesresistancewithfrequency.
In general, any given oscillator frequency (fOSC) should be
obtained using the lowest master oscillator frequency.
Lower master oscillator frequencies use less power and
are more accuate. For instance, fOSC = 100kHz can be
obtained by either RSET = 10k, N = 100, master oscillator
=10MHzorRSET =100k, N=10, masteroscillator=1MHz.
The RSET = 100k is preferred for lower power and better
accuracy.
RSET = 10k • [10MHz/(N • fOSC)], N = 1, 10, 100
(RSETMIN = 3.32k (5V Supply), 5k (3V Supply),
RSETMAX = 1M)
Any resistor, RSET, tolerance adds to the inaccuracy of the
oscillator, fOSC
.
Settling Time
The settling time is proportional to RSET and is approxi-
mately tSETTLE ≈ RSET • (5µs/kΩ). This parameter is
guaranteed by design and not 100% tested.
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PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
S5 Package
5-Lead Plastic SOT-23
(LTC DWG # 05-08-1633)
2.60 – 3.00
(0.102 – 0.118)
2.80 – 3.00
(0.110 – 0.118)
(NOTE 3)
1.50 – 1.75
(0.059 – 0.069)
0.00 – 0.15
(0.00 – 0.006)
0.90 – 1.45
(0.035 – 0.057)
0.35 – 0.55
(0.014 – 0.022)
0.35 – 0.50
(0.014 – 0.020)
FIVE PLACES (NOTE 2)
0.90 – 1.30
(0.035 – 0.051)
0.09 – 0.20
(0.004 – 0.008)
(NOTE 2)
0.95
(0.037)
REF
1.90
(0.074)
REF
NOTE:
S5 SOT-23 0599
1. DIMENSIONS ARE IN MILLIMETERS
2. DIMENSIONS ARE INCLUSIVE OF PLATING
3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
4. MOLD FLASH SHALL NOT EXCEED 0.254mm
5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)
1799i LT/TP 0101 2K • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
4
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
LINEAR TECHNOLOGY CORPORATION 2001
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