LTC6905-XXX Series
Fixed Frequency
SOT-23 Oscillator
FEATURES
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■
DESCRIPTIO
No External Components to Set Frequency
Frequency Error
±0.5%
Typical
Fast Start-Up Time: 100µs Typical
±20ppm/°C
Temperature Stability
Output Enable Provided
Includes Divide by 1, 2 or 4
Rise Time: 0.5ns, C
L
= 5pF
Timing Jitter: <0.8% Typical
50%
±2.5%
Duty Cycle
I
S
= 8mA Typical (f
OSC
= 100MHz, C
L
= 5pF)
CMOS Output Drives 600Ω Load
Single Supply 2.7V to 5.5V
Low Profile (1mm) ThinSOT
TM
Package
The LTC
®
6905-XXX series of parts are precision, fixed
frequency, silicon oscillators designed to minimize board
space while maximizing accuracy and ease of use.
Programmed at the factory to a fixed frequency, the
LTC6905-XXX series of parts need no external trim com-
ponents. An internal three-state divider allows for division
of the master clock by 1, 2 or 4, providing 3 frequencies
(for each device).
The LTC6905-XXX series operate with a single 2.7V to
5.5V power supply and provide a rail-to-rail, 50% duty
cycle, square wave output. The OE pin will disable the
output when brought low and synchronously enable the
output when brought high, avoiding pulse slivers.
The four products of the LTC6905-XXX family are:
LTC6905-133: f
OSC
= 133MHz, 66.7MHz, 33.3MHz
LTC6905-100: f
OSC
= 100MHz, 50MHz, 25MHz
LTC6905-96: f
OSC
= 96MHz, 48MHz, 24MHz
LTC6905-80: f
OSC
= 80MHz, 40MHz, 20MHz
The LTC6905-XXX series of parts are designed with a factory
trim option to modify the divider ratios from 1, 2, 4 to 8, 16,
32. A second trim option allows for additional master clock
frequencies. For the alternate divider ratios and unlisted
frequencies, contact LTC marketing.
APPLICATIO S
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Data Clocks for High Reliability Applications
High Vibration, High Acceleration Environments
Replacement for Fixed Crystal and Ceramic
Oscillators
, LTC and LT 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.
TYPICAL APPLICATIO
Typical Distribution of Frequency Error, T
A
= 25°C
40
V
S
= 3V
Basic Connection
f
OSC
= 133MHz
UNITS
30
3V
0.1µF
1
2
3
OUT
V
+
LTC6905-133
GND
OE
DIV
6905x TA01
5
20
3V
÷1
4
÷4
÷2
OPEN
10
0
–1
–0.5
0.0
0.5
% FREQUENCY ERROR
1
6905x TA02
U
6905xf
U
U
1
LTC6905-XXX Series
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
+
1
GND 2
OE 3
4 DIV
5 OUT
Supply Voltage (V
+
) to GND ........................– 0.3V to 6V
DIV to GND .................................... – 0.3V to (V
+
+ 0.3V)
OE to GND ..................................... – 0.3V to (V
+
+ 0.3V)
Output Short-Circuit Duration (Note 6) ........... Indefinite
Operating Temperature Range (Note 8)
LTC6905C .......................................... – 40°C to 85°C
LTC6905I ............................................ – 40°C to 85°C
LTC6905H ........................................ – 40°C to 125°C
Specified Temperature Range (Note 8)
LTC6905C ............................................... 0°C to 70°C
LTC6905I ............................................ – 40°C to 85°C
LTC6905H ........................................ – 40°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER PART NUMBER
LTC6905CS5-133
LTC6905IS5-133
LTC6905HS5-133
LTC6905CS5-100
LTC6905IS5-100
LTC6905HS5-100
LTC6905CS5-96
LTC6905IS5-96
LTC6905HS5-96
LTC6905CS5-80
LTC6905IS5-80
LTC6905HS5-80
S5 PART MARKING*
LTBPM
LTBPK
LTBPJ
LTBPH
*The temperature grade is identified by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
SYMBOL
∆f
PARAMETER
Frequency Accuracy (Notes 2, 7)
The
●
denotes the specifications which apply over the full specified
temperature range, otherwise specifications are at T
A
= 25°C or as noted. OE = DIV = V
+
, V
+
= 2.7V to 3.6V, R
L
= 15k, C
L
= 5pF, unless
otherwise noted. All voltages are with respect to GND.
CONDITIONS
LTC6905C-XXX
T
A
= 25°C, V
+
= 3V
0°C < T
A
< 70°C
LTC6905I-XXX
25°C < T
A
< 85°C
– 40°C < T
A
< 85°C
LTC6905H-XXX
25°C < T
A
< 125°C
– 40°C < T
A
< 125°C
V
+
= 5V
MIN
TYP
±0.5
●
MAX
±1.0
±1.5
±1.8
±2.9
±2.3
±2.9
UNITS
%
%
%
%
%
%
%
ppm/°C
%/V
%
ppm/√kHr
●
●
±1.5
●
∆f/∆T
∆f/∆V
Freq Drift Over Temp (Note 2)
Freq Drift Over Supply (Notes 2, 7)
Timing Jitter (Note 3)
Long-Term Stability of Output Frequency
Duty Cycle
V
+
= 2.7V to 3.6V
±20
0.5
0.8
300
●
●
47.5
2.7
50
52.5
5.5
V
+
Operating Supply Range
2
U
%
V
6905xf
W
U
U
W W
W
LTC6905-XXX Series
ELECTRICAL CHARACTERISTICS
SYMBOL
I
S
PARAMETER
Power Supply Current
The
●
denotes the specifications which apply over the full specified
temperature range, otherwise specifications are at T
A
= 25°C or as noted. OE = DIV = V
+
, V
+
= 2.7V to 3.6V, R
L
= 15k, C
L
= 5pF, unless
otherwise noted. All voltages are with respect to GND.
CONDITIONS
DIV = V
+
(÷ 1), V
+
= 3.6V
LTC6905-133
LTC6905-100
LTC6905-96
LTC6905-80
DIV = 0 (÷ 4), V
+
= 3.6V
LTC6905-133
LTC6905-100
LTC6905-96
LTC6905-80
●
●
●
●
●
●
●
●
●
V
+
– 0.15
●
MIN
TYP
10
8
8
7
5
4
4
3.5
MAX
15
12
12
11
8
7
7
6
0.2
UNITS
mA
mA
mA
mA
mA
mA
mA
mA
V
V
µA
µA
µA
µA
V
V
V
V
V
IH
V
IL
I
DIV
I
OE
V
OH
High Level DIV or OE Pins Input Voltage
Low Level DIV or OE Pins Input Voltage
DIV Input Current (Note 4)
OE Input Current (Note 4)
High Level Output Voltage (Note 4)
DIV = V
+
DIV = 0V
OE = V
+
OE = 0V
V
+
= 5.5V
V
+
= 2.7V
V
+
= 5.5V
V
+
= 5.5V
V
+
= 5.5V
V
+
= 5.5V
I
OH
= – 1mA
I
OH
= – 4mA
I
OH
= – 1mA
I
OH
= – 4mA
I
OL
= 1mA
I
OL
= 4mA
I
OL
= 1mA
I
OL
= 4mA
●
●
– 40
15
– 11
15
–11
40
●
●
●
●
●
●
●
●
5.25
5.20
2.5
2.3
5.45
5.30
2.6
2.5
0.05
0.2
0.1
0.4
0.5
0.25
0.3
0.3
0.5
V
OL
Low Level Output Voltage (Note 4)
V
+
= 5.5V
V
+
= 2.7V
V
V
V
V
ns
t
r
, t
f
OUT Rise/Fall Time (Note 5)
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2:
Frequency accuracy is tested with DIV = V
+
(÷1). 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.
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.
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 LTC6905 is optimized for the performance with a 3V power
supply voltage. Refer to Typical Performance Characteristics curves in this
data sheet for additional information regarding the LTC6905 voltage
coefficient, especially between 4.5V and 5.5V. Please consult LTC
Marketing for parts optimized for 5V operation.
Note 8:
The LTC6905C-XXX is guaranteed functional over the operating
temperature range and 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.
6905xf
3
LTC6905-XXX Series
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Frequency
18
16
SUPPLY CURRENT (mA)
5.5V
2.7V
12
10
8
6
4
2
0
÷4
÷4
÷2
÷2
÷1
FREQUENCY ERROR (%)
14
0
50
FREQUENCY (MHz)
6905x G01
R
OUT
vs V
+
45
40
1.00
1.20
OUTPUT RESISTANCE (Ω)
÷1
PERCENTAGE ERROR (%)
35
30
25
20
15
10
0.20
0.80
JITTER (%)
5
0
2.5
3
3.5
4
4.5
SUPPLY VOLTAGE (V)
5
5.5
0
0
20
40
60 80 100 120 140 160 180
FREQUENCY (MHz)
6905x G05
LTC6905-80 Output Operating at
20MHz, V
S
= 3V
0.75V/DIV
4
U W
÷1
100
6905x G04
Frequency Error vs Supply Voltage
2.50
2.00
LTC6905-133
1.50
1.00
0.50
O
–0.50
LTC6905-100
LTC6905-96
LTC6905-80
2.5
3
3.5
4
4.5
SUPPLY VOLTAGE (V)
5
5.5
6905x G09
150
200
Jitter vs Frequency
1.0
0.8
÷4
÷2
Frequency vs Temperature
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–40 –20
0
20 40 60 80 100 120
TEMPERATURE (°C)
6905x G08
0.60
0.40
LTC6905-133 Output Operating at
133MHz, V
S
= 3V
0.75V/DIV
10ns/DIV
6905x G06
2.5ns/DIV
6905x G07
6905xf
LTC6905-XXX Series
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 the GND (Pin 2) with a 0.1µF capacitor
or higher.
GND (Pin 2):
Ground. Should be tied to a ground plane for
best performance.
OE (Pin 3):
Output Enable. Pull to V+ or leave floating to
enable the output driver (Pin 5). Pull low to disable the
output. The output is disabled asynchronously. Pulling OE
pin low will immediately disable the output. Pulling the OE
pin high will bring the output high on the next low to high
transition of the clock. This eliminates pulse slivers.
DIV (Pin 4):
Divider-Setting Input. This three-state input
selects among three divider settings. Pin 4 should be tied
to V
+
for the
÷1
setting, the highest frequency range. Float-
ing 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 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 15µA. Likewise, driving
DIV low requires sinking 15µA. 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 cou-
pling from other PCB traces.
OUT (Pin 5):
Oscillator Output. This pin can drive 5kΩ
and/or 5pF loads. For heavier loads, refer to the Applica-
tions Information section.
BLOCK DIAGRA
1
V
+
R
SET
+
–
2
GND
–
V
BIAS
I
RES
+
GND
Table 1. LTC6905-XXX Frequency Settings
DIV SETTING
V+
OPEN
GND
LTC6905-133
133.33MHz
66.66MHz
33.33MHz
LTC6905-100
100MHz
50MHz
25MHz
LTC6905-96
96MHz
48MHz
24MHz
LTC6905-80
80MHz
40MHz
20MHz
W
U
U
U
3
V
RES
= 1V
±5%
(V
+
– V
SET
)
OE
PROGRAMMABLE
DIVIDER
(N = 1, 2 OR 4)
MASTER OSCILLATOR
DIVIDER
SELECT
f
MO
THREE-STATE
INPUT DETECT
V
+
15µA
DIV
4
f
OSC
=
f
MO
N
OUT
5
+
I
RES
GAIN = 1
–
15µA
6905x BD
6905xf
5
测试/测量
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