LTC6905CS5#TRM [Linear]
LTC6905 - 17MHz to 170MHz Resistor Set SOT-23 Oscillator; Package: SOT; Pins: 5; Temperature Range: 0°C to 70°C;
| 型号： | LTC6905CS5#TRM |
| 厂家： | 
Linear |
| 描述： | LTC6905 - 17MHz to 170MHz Resistor Set SOT-23 Oscillator; Package: SOT; Pins: 5; Temperature Range: 0°C to 70°C 光电二极管 |
| 文件： | 总12页 (文件大小：161K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC6905
17MHz to 170MHz
Resistor Set SOT-23 Oscillator
FEATURES
DESCRIPTION
The LTC®6905 precision, programmable silicon oscilla-
tor is easy to use and occupies very little board space. It
requires only a single resistor to set the output frequency
from 17MHz to 170MHz with a typical frequency error of
0.5% or less.
n
One External Resistor Sets the Frequency
n
Fast Start-Up Time: 100μs Typical
n
Frequency Range: 17MHz to 170MHz
n
Frequency Error 0.5% Typ 17MHz to 170MHz
(T = 0°C to 70°C, Over All Settings)
A
n
20ppm/°C Temperature Stability
The LTC6905 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. Operation is simple: A
n
Rise Time: 0.5ns, C = 5pF
L
n
n
n
n
n
n
Timing Jitter: 7.2ps RMS at 170MHz
50% 2.5% Duty Cycle
6mA Typical Supply Current, f
= 100MHz
S
OSC
single resistor, R , between 10k to 25k is used to set
SET
CMOS Output Drives 500Ω Load (V = 3V)
the frequency, and an internal three-state divider (DIV
Operates from a Single 2.7V to 5.5V Supply
input) allows for division of the master clock by 1, 2 or 4,
™
Low Profile (1mm) ThinSOT Package
providing three frequencies for each R value.
SET
The LTC6905 features a proprietary feedback loop that
APPLICATIONS
linearizes the relationship between R
and frequency,
SET
eliminating the need for tables to calculate frequency. The
oscillator can be easily programmed using the simple
formula outlined below:
n
High Frequency Precision Oscillator
n
High Speed Data Bus Clock
n
Fixed Crystal Oscillator Replacement
Ceramic Oscillator Replacement
n
1, DIV Pin = V+
⎧
⎪
⎛168.5MHz •10kΩ
⎞
1
⎠ N
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6614313, 6342817.
fOSC
=
+ 1.5MHz • , N = 2, DIV Pin = Open
⎜
⎟
⎨
⎝
RSET
⎪
4,DIV Pin = GND
⎩
For higher accuracy, fixed frequency versions that
include an internal frequency-setting resistor, see the
LTC6905-XXX Series data sheet
.
TYPICAL APPLICATION
Typcial Distribution of Frequency Error, TA = 25°C
60
+
V
R
= 3V
= 12k
SET
50
DIV = 1
Basic Connection
40
30
17.225MHz ≤ f
5
≤ 170MHz
OSC
5V
1
2
3
+
V
OUT
LTC6905
0.1μF
5V
10k ≤ R
≤ 25k
20
10
0
SET
GND
SET
÷1
÷4
4
÷2
DIV
OPEN
6905 TA01
–0.5
–0.3
–0.1
0.1
0.3
0.5
6905 TA02
% ERROR
NOTE: RESISTOR, R , TOLERANCE WILL ADD
SET
TO THE FREQUENCY ERROR
6905fd
1
LTC6905
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
(Note 1)
+
TOP VIEW
+
Supply Voltage (V ) to GND.........................–0.3V to 6V
+
+
DIV to GND .................................... –0.3V to (V + 0.3V)
V
1
5 OUT
4 DIV
GND 2
SET 3
SET to GND.................................... –0.3V to (V + 0.3V)
Output Short-Circuit Duration (Note 6) ........... Indefinite
Operating Temperature Range (Note 7)
S5 PACKAGE
5-LEAD PLASTIC SOT-23
LTC6905C, I .........................................–40°C to 85°C
LTC6905H ..........................................–40°C to 125°C
LTC6905MP .......................................–55°C to 125°C
Specified Temperature Range (Note 8)
T
= 125°C, θ = 160°C/W
JA
JMAX
LTC6905C ................................................ 0°C to 70°C
LTC6905I..............................................–40°C to 85°C
LTC6905H ..........................................–40°C to 125°C
LTC6905MP .......................................–55°C to 125°C
Storage Temperature Range...................–65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL (MINI)
LTC6905CS5#TRMPBF
LTC6905IS5#TRMPBF
LTC6905HS5#TRMPBF
LTC6905MPS5#TRMPBF
LEAD BASED FINISH
TAPE AND REEL (MINI)
LTC6905MPS5#TRM
TAPE AND REEL
PART MARKING*
LTBJC
LTBJC
LTBJC
LTDVW
PACKAGE DESCRIPTION
5-Lead Plastic SOT-23
5-Lead Plastic SOT-23
5-Lead Plastic SOT-23
5-Lead Plastic SOT-23
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
–55°C to 125°C
LTC6905CS5#TRPBF
LTC6905IS5#TRPBF
LTC6905HS5#TRPBF
LTC6905MPS5#TRPBF
TAPE AND REEL
LTC6905MPS5#TR
PART MARKING*
LTDVW
PACKAGE DESCRIPTION
5-Lead Plastic SOT-23
TEMPERATURE RANGE
–55°C to 125°C
TRM = 500 pieces. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
6905fd
2
LTC6905
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full specified
temperature range, otherwise specifications are at TA = 25°C or as noted. V+ = 2.7V to 5.5V, RL = 15k, CL = 5pF, Pin 4 = V+ unless
otherwise noted. All voltages are with respect to GND.
SYMBOL PARAMETER
Δf Frequency Accuracy (Notes 2, 9)
CONDITIONS
MIN
TYP
MAX
UNITS
+
+
V = 2.7V, 17.225MHz < f < 170MHz
0.5
1.4
2.2
%
%
V = 5V, 17.225MHz < f < 170MHz
LTC6905CS5
+
+
l
l
V = 2.7V, 17.225MHz < f < 170MHz
1.7
2.5
%
%
V = 5V, 17.225MHz < f < 170MHz
LTC6905MPS5 (25°C ≤ T ≤ 125°C),
LTC6905HS5 (25°C ≤ T ≤ 125°C),
LTC6905IS5 (25°C ≤ T ≤ 85°C)
V+ = 2.7V, 17.225MHz < f < 170MHz
V+ = 5V, 17.225MHz < f < 170MHz
LTC6905MPS5 (–55°C < T < 125°C),
LTC6905HS5 (–40°C ≤ T ≤ 125°C),
LTC6905IS5 (–40°C ≤ T ≤ 85°C)
1.9
2.9
%
%
+
+
l
l
V = 2.7V, 17.225MHz < f < 170MHz
3.5
3.5
%
%
V = 5V, 17.225MHz < f < 170MHz
Δf
Frequency Accuracy (Notes 2, 9)
Frequency-Setting Resistor Range
Maximum Frequency
R
10
25
kΩ
MHz
SET
MAX
MIN
+
f
f
Pin 4 = V , N = 1
170
17.225
20
Minimum Frequency
Pin 4 = 0V, N = 4
MHz
l
l
Δf/ΔT
Δf/ΔV
Freq Drift Over Temp (Note 2)
Freq Drift Over Supply (Notes 2, 9)
Peak-to-Peak Timing Jitter (Note 3)
Long-Term Stability of Output Frequency
Duty Cycle
R
= 10k
ppm/°C
%/V
SET
+
V = 2.7V to 5.5V, R
= 10k
0.5
SET
0.8
%
300
50
ppm/√kHr
%
l
l
47.5
2.7
52.5
5.5
+
V
Operating Supply Range
V
+
l
l
I
S
Power Supply Current
R
OSC
= 10k, N = 1, R = ∞,
V = 5.5V
14
7
20
12
mA
mA
SET
L
+
f
= 170MHz, C = 5pF
V = 2.7V
L
+
l
l
R
OSC
= 20k, N = 4, R = ∞,
V = 5.5V
5
3
7
5
mA
mA
SET
L
+
f
= 21.44MHz, C = 5pF
V = 2.7V
L
+
l
l
l
V
V
High Level DIV Input Voltage
Low Level DIV Input Voltage
DIV Input Current (Note 4)
V – 0.15
V
V
IH
0.2
40
IL
+
+
I
Pin 4 = V
V = 5.5V
15
–11
μA
μA
DIV
+
Pin 4 = 0V
V = 5.5V
–40
+
l
l
V
OH
High Level Output Voltage (Note 4)
V = 5.5V, Pin 4 = 0V
I
I
= –1mA
= –4mA
5.25
5.20
5.45
5.30
V
V
OH
OH
+
l
l
V = 2.7V, Pin 4 = 0V
I
I
= –1mA
= –4mA
2.5
2.4
2.6
2.4
V
V
OH
OH
6905fd
3
LTC6905
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full specified
temperature range, otherwise specifications are at TA = 25°C or as noted. V+ = 2.7V to 5.5V, RL = 15k, CL = 5pF, Pin 4 = V+ unless
otherwise noted. All voltages are with respect to GND.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
l
l
V
Low Level Output Voltage (Note 4)
V = 5.5V, Pin 4 = 0V
I
I
= 1mA
= 4mA
0.05
0.2
0.25
0.3
V
V
OL
OL
OL
+
l
l
V = 2.7V, Pin 4 = 0V
I
I
= 1mA
= 4mA
0.1
0.4
0.3
0.5
V
V
OL
OL
t , t
OUT Rise/Fall Time (Note 5)
0.5
ns
r
f
+
l
l
V
SET
Voltage at R Pin
V = 5.5V
4.27
1.61
4.5
1.7
4.73
1.79
V
V
SET
+
V = 2.7V
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 6: A heat sink may be required to keep the junction temperature
below the absolute maximum when the output is shorted indefinitely.
Note 7: The LTC6905C is guaranteed functional over the operating
temperature range.
Note 2: Frequency accuracy is defined as the deviation from the f
equation. Accuracy is tested with DIV = V , N = 1 and other divide ratios
are guaranteed by design.
Note 3: 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.
OSC
Note 8: The LTC6905C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6905C-XXX is designed, characterized and expected
to meet specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LTC6905I-XXX is guaranteed to meet
specified performance from –40°C to 85°C.
Note 9: The LTC6905 is optimized for the performance with a 3V power
supply voltage. Please consult LTC Marketing for parts optimized for 5V
operation.
+
Note 4: To conform with the Logic IC Standard convention, current out of
a pin is arbitrarily given as a negative value.
Note 5: Output rise and fall times are measured between the 10% and
90% power supply levels.
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Frequency
Frequency Error vs RSET
Frequency Error vs Supply Voltage
0.60
0.40
0.20
0
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0
18
16
14
12
10
8
5.5V
2.7V
÷1
÷2
–0.20
–0.40
–0.60
–0.80
÷1
÷4
6
÷2
4
÷4
–0.20
2
–0.40
0
12
14
16
R
18
20
24
10
22
100
FREQUENCY (MHz)
2.5
3
3.5
4
5.5
0
50
150
200
4.5
5
(kΩ)
SUPPLY VOLTAGE (V)
SET
6905 G02
6905 G03
6905 G01
6905fd
4
LTC6905
TYPICAL PERFORMANCE CHARACTERISTICS
ROUT vs V+
Jitter vs Frequency
Frequency vs Temperature
1.0
0.8
45
40
35
30
25
20
15
10
5
1.20
1.00
0.6
÷4
÷2
÷1
0.4
0.80
0.2
0
0.60
0.40
–0.2
–0.4
–0.6
–0.8
–1.0
0.20
0
0
–40 –20
0
20 40 60 80 100 120
TEMPERATURE (°C)
0
20 40 60 80 100 120 140 160 180
FREQUENCY (MHz)
2.5
3
3.5
4
5.5
4.5
5
SUPPLY VOLTAGE (V)
6905 G08
6905 G05
6905 G04
LTC6905 Output Operating at
17.5MHz, VS = 3V
LTC6905 Output Operating at
170MHz, VS = 3V
1V/DIV
1V/DIV
6905 G06
6905 G07
12.5ns/DIV
1ns/DIV
PIN FUNCTIONS
+
+
+
V (Pin 1): Voltage Supply (2.7V ≤ V ≤ 5.5V). This sup-
ply must be kept free from noise and ripple. It should be
bypassed directly to the GND (Pin 2) with a 0.1μF capaci-
tor or higher.
of N in the frequency equation. Pin 4 should be tied to V
for the ÷1 setting, the highest frequency range. Floating
Pin 4 divides the master oscillator by 2. Pin 4 should
be tied to GND for the ÷4 setting, the lowest frequency
range. To detect a floating DIV pin, the LTC6905 attempts
to pull the pin toward midsupply. This is realized with two
GND (Pin 2): Ground. Should be tied to a ground plane
for best performance.
+
internal current sources, one tied to V and Pin 4 and the
SET (Pin 3): Frequency-Setting Resistor Input. The value
other one tied to ground and Pin 4. Therefore, driving
the DIV pin high requires sourcing approximately 15μA.
Likewise, driving DIV low requires sinking 11μA. When
Pin 4 is floated, 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.
+
of the resistor connected between this pin and V deter-
mines the oscillator frequency. The voltage on this pin is
+
held by the LTC6905 to approximately 1V below the V
voltage. For best performance, use a precision metal film
resistor with a value between 10k and 25k and limit the
capacitance on this pin to less than 10pF.
OUT (Pin 5): Oscillator Output. This pin can drive 5kΩ
and/or5pFloads.Forlargerloads,refertotheApplications
DIV (Pin 4): Divider-Setting Input. This three-state input
selectsamongthreedividersettings,determiningthevalue
Information section.
6905fd
5
LTC6905
BLOCK DIAGRAM
f
V
= 1V 5%
MO
N
RES
f
=
+
+
OSC
PROGRAMMABLE
DIVIDER
(÷1, 2 OR 4)
(V – V
)
V
OUT
SET
1
5
+
R
SET
GAIN = 1
MASTER OSCILLATOR
I
RES
+
SET
DIVIDER
SELECT
V
3
2
–
15μA
DIV
–
+
THREE-STATE
INPUT DETECT
4
+
V
BIAS
–
I
RES
15μA
GND
GND
6905 BD
6905fd
6
LTC6905
THEORY OF OPERATION
As shown in the Block Diagram, the LTC6905’s master
highestfrequencyrange,withthemasteroutputfrequency
passeddirectlytoOUT.TheDIVpinmaybefloatedordriven
to midsupply to select ÷2, the intermediate frequency
range. The lowest frequency range, ÷4, is selected by
tying DIV to GND or driving it below 0.5V. Figure 1 shows
oscillator is controlled by the ratio of the voltage between
+
the V and SET pins and the current entering the SET pin
(I ). The voltage on the SET pin is forced to approxi-
RES
+
mately 1V below V by the PMOS transistor and its gate
bias voltage.
the relationship between R , divider setting and output
SET
frequency, including the overlapping frequencies.
+
A resistor R , connected between the V and SET pins,
SET
+
30
“locks together” the voltage (V – V ) and current, I
,
SET
RES
variation. This provides the LTC6905’s high precision. The
25
master oscillation frequency reduces to:
÷4 ÷2
÷1
20
15
10
5
168.5MHz •10kΩ
fMO
=
+ 1.5MHz
RSET
Toextendtheoutputfrequencyrange,themasteroscillator
signal is divided by 1, 2 or 4 before driving OUT (Pin 5).
The LTC6905 is optimized for use with resistors between
10k and 25k, corresponding to oscillator frequencies
between 17.225MHz and 170MHz. The divide-by value is
determined by the state of the DIV input (Pin 4). Tie DIV to
10
60
110
OUTPUT FREQUENCY (MHz)
160
6905 F01
+
+
Figure 1. RSET vs Output Frequency
V or drive it to within 0.4V of V to select ÷1. This is the
6905fd
7
LTC6905
APPLICATIONS INFORMATION
SELECTING THE DIVIDER SETTING AND RESISTOR
to 90% of the rise or fall transition). If the total output rise
time plus fall time is arbitrarily specified to be equal to
The LTC6905’s master oscillator has a frequency range
spanning 68.9MHz to 170MHz. A programmable divider
extendsthefrequencyrangefrom17.225MHzto170MHz.
Table 1 describes the recommended frequencies for each
divider setting. Note that the ranges overlap; at some fre-
quencies there are two divider/resistor combinations that
result in the same frequency. Choosing a higher divider
setting will result in less jitter at the expense of slightly
higher supply current.
or less than 20% of the oscillator’s period (1/f ), then
OSC
the maximum output C
in picofarads (pF) should be
LOAD
equal to or less than [45454/(R
• f )] (R
in ohms
OUT OSC
OUT
and f
in MHz).
OSC
Example: An LTC6905 is operating with a 3V power supply
and is set for a f
= 50MHz.
OSC
+
+
R
with V = 3V is 27Ω (using the R
vs V graph in
OUT
OUT
the Typical Performance Characteristics).
Table 1. Frequency Range vs Divider Setting
The maximum output C
should be equal to or less
LOAD
DIVIDER SETTING
FREQUENCY RANGE
than [45454/(27 • 50)] = 33.6pF.
+
68.9MHz to 170MHz
÷1
⇒
DIV (Pin 4) = V
The lowest resistive load Pin 5 can drive can be calculated
usingtheminimumhighleveloutputvoltageintheElectrical
Characteristics. With a V equal to 5.5V and 4mA output
34.45MHz to 85MHz
17.225MHz to 43MHz
÷2
÷4
⇒
⇒
DIV (Pin 4) = Floating
DIV (Pin 4) = GND
+
current, the minimum high level output voltage is 5V and
thelowestresistiveloadPin5candriveis1.25k(5V/4mA).
After choosing the proper divider setting, determine the
correct frequency-setting resistor. Because of the linear
correspondencebetweenoscillationperiodandresistance,
a simple equation relates resistance with frequency.
+
With a V equal to 2.7V and 4mA output current, the
minimum high level output voltage is 1.9V and the lowest
resistive load Pin 5 can drive is 475Ω (1.9V/4mA).
⎧
1
⎛
⎞
168.5MHz
⎪
RSET = 10k •
, N = 2
⎨
FREQUENCY ACCURACY AND POWER SUPPLY NOISE
⎜
⎟
f
•N – 1.5MHz
⎝
⎠
OSC
⎪
4
⎩
The frequency accuracy of the LTC6905 may be affected
when its power supply generates noise with frequency
(R
= 10k, R
= 25k)
SETMIN
SETMAX
contents equal to f /64 or its multiples (f
is the
MO
MO
Any resistor, R , tolerance adds to the inaccuracy of
SET
OSC
internal LTC6905 master oscillator frequency before the
the oscillator. f
.
divider and f /64 is the master oscillator control loop
MO
frequency). Ifforexample, themasteroscillatorfrequency
is set equal to 80MHz and the LTC6905 is powered by a
switching regulator, then the oscillator frequency may
show an additional error if the switching frequency is
1.4MHz (80MHz/64).
START-UP TIME
The start-up time and settling time to within 1% of the
final frequency is typically 100μs.
MAXIMUM OUTPUT LOAD
JITTER AND POWER SUPPLY NOISE
The LTC6905 output (Pin 5) can drive a capacitive load
If the LTC6905 is powered by a supply that has frequency
contentsequaltotheoutputfrequencythentheoscillators
jitter may increase. In addition, power supply ripple in
excess of 20mV at any frequency may increase jitter.
(C ) of 5pF or more. Driving a C
LOAD
greater than 5pF
OSC
LOAD
depends on the oscillator’s frequency (f ) and output
resistance (R ). The output rise time or fall time due to
OUT
R
OUT
and C
is equal to 2.2 • R
• C
(from 10%
LOAD
OUT
LOAD
6905fd
8
LTC6905
APPLICATIONS INFORMATION
JITTER AND DIVIDE RATIO
1) Thebypasscapacitormustbeplacedascloseaspossible
to the LTC6905, and no vias should be placed between
the capacitor and the LTC6905. The bypass capacitor
must be on the same side of the circuit board as the
LTC6905.
At a given output frequency, a higher master oscillator
frequency and a higher divide ratio will result in lower
jitter and higher power supply dissipation. Indeterminate
jitter percentage will decrease by a factor of slightly less
than the square root of the divider ratio, while determinate
jitter will not be similarly attenuated. Please consult the
specificationtablesandJittervsFrequencygraphshowing
jitter at various divider ratios.
2) The resistor R should be placed as close as possible
SET
to the LTC6905, and the connection of R
to V
SET
CC
should be closely shared with the bypass capacitor.
The resistor R may be placed on the opposite side
SET
of the board from the LTC6905, directly underneath the
bypass capacitor.
JITTER AND STRAY CAPACITANCE ON THE SET PIN
(PIN 3)
3) Ifagroundplaneisused,theconnectionoftheLTC6905
to the ground plane should be as close as possible
to the LTC6905 GND pin and should be composed of
multiple, high current capacity vias.
The stray capacitance on the SET pin (Pin 3) should be
limited to 10pF or less to avoid increased jitter or unstable
oscillation.
LTC6905 SUGGESTED CRITICAL COMPONENT LAYOUT
R
C
In order to provide the specified performance, it is re-
LTC6905
quired that the frequency setting resistor R
and the
SET
supply bypass capacitor be placed as close as possible
to the LTC6905. The following additional rules should be
followed for best performance:
6905 F02
Figure 2. LTC6905 Suggested Critical Component Layout
6905fd
9
LTC6905
APPLICATIONS INFORMATION
ALTERNATIVE METHODS OF SETTING THE OUTPUT
Figure 3 shows a method to control the frequency of the
FREQUENCY OF THE LTC6905
LTC6905 using a current source. R , in this case, sets a
SET
maximum frequency according to the regular expression
The LTC6905 may be programmed by any method that
sources a current into the SET pin (Pin 3). The accuracy
of the programming is best with a simple resistor because
theLTC6905takesintoaccountboththevoltageattheSET
pin and the current into the SET pin when generating the
output frequency. Since the voltage at the SET pin can
vary by as much as 5%, setting the frequency using a
current rather than a resistor will result in as much as 5%
additional inaccuracy in the output frequency.
for f . The current source will subtract current from the
OSC
SET pin to lower the frequency.
Figure 4 shows a method for controlling the frequency
of the LTC6905 using a voltage source. In this case, R
SET
will
sets a constant current into the SET pin, and R
CNTRL
subtractfromthiscurrentinordertochangethefrequency.
Increasing V
will increase the output frequency.
CNTRL
+
⎡
⎤
⎥
⎥
⎥
⎥
⎡
⎢
⎣
⎤
⎥
⎦
V – VSET
RSET
⎢168.5MHz •10kΩ •
–ICNTRL
+
⎢
⎢
1
N
⎢
⎥
V
fOSC
=
+ 1.5MHz
1
2
3
5
4
+
V+ – VSET
V
OUT
⎢
LTC6905
0.1μF
SET
f
OSC
⎢
⎥
69.8MHz TO 170MHz
GND
SET
R
10k
⎣
⎦
+
V
DIV
N = 1
I
Frequency ≤ 100kHz
I
CNTRL
CNTRL
6905 F03
0μA TO 60μA
+
Figure 3. Current Controlled Oscillator
Example (Figure 3): V = (V – 1V), R = 10k, N = 1
SET
SET
f
= [168.5MHz • (1 – 10kΩ • I ) + 1.5MHz
CNTRL
OSC
+
⎡
⎤
⎥
⎥
⎥
⎥
⎡
⎢
⎣
⎤
⎥
⎦
V – VSET VSET – VCNTRL
+
V
= 3V
⎢168.5MHz •10kΩ •
–
1
2
3
5
4
+
RSET
V+ – VSET
RCNTRL
V
OUT
⎢
⎢
⎢
1
N
⎢
⎥
fOSC
=
+ 1.5MHz
LTC6905
0.1μF
SET
f
OSC
69.8MHz TO 170MHz
GND
SET
R
10k
⎢
⎥
+
V
DIV
⎣
⎦
N = 1
R
CNTRL
6905 F04
33.2k
V
Frequency ≤ 100kHz
CNTRL
V
CNTRL
+
–
0V TO 2V
+
Example (Figure 4): V = (V – 1V), R = 10k, R = 33.2k,
CNTRL
SET
SET
Figure 4. Voltage Controlled Oscillator
+
N = 1, V = 3V
⎡
⎤
⎡
⎤
2V – VCNTRL
33.2kΩ
1
fOSC = 168.5MHz •10kΩ •
–
+ 1.5MHz
⎢
⎥
⎢
⎥
10kΩ
⎣
⎦
⎣
⎦
6905fd
10
LTC6905
PACKAGE DESCRIPTION
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
0.62
MAX
0.95
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.50 – 1.75
(NOTE 4)
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
PIN ONE
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.90 BSC
0.09 – 0.20
(NOTE 3)
NOTE:
S5 TSOT-23 0302
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
6905fd
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
LTC6905
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1799
1kHz to 33MHz ThinSOT Oscillator
Single Output, High Frequency Operation
Single Output Lower Power
LTC6900
1kHz to 20MHz ThinSOT Oscillator
LTC6902
Multiphase Oscillator with Spread Spectrum Modulation
1kHz to 68MHz Serial Port Programmable Oscillator
Fixed Frequency LTC6905
2-, 3- or 4-Phase Outputs
2
™
LTC6903/LTC6904
LTC6905-XXX Series
LTC6906
3-Wire or I C Programmable
High Accuracy, No External Resistor
Micropower, 10kHz to 1MHz Resistor Set ThinSOT Oscillator
Ultralow Power, Resistor Sets Frequency
6905fd
LT 0808 REV D • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
© LINEAR TECHNOLOGY CORPORATION 2005
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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