SIT8918BE-11-33N-54.000000E 数据手册
SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Features
Applications
Frequencies between 1 MHz and 110 MHz accurate to 6 decimal
places
Industrial, medical, non AEC-Q100 automotive, avionics and
other high temperature applications
Operating temperature from -40°C to 125°C. For -55°C option, refer
to SiT8920 and SiT8921
Industrial sensors, PLC, motor servo, outdoor networking
equipment, medical video cam, asset tracking systems, etc.
Supply voltage of 1.8V or 2.5V to 3.3V
Excellent total frequency stability as low as ±20 ppm
Low power consumption of 3.5 mA typical at 1.8V
LVCMOS/LVTTL compatible output
Industry-standard packages: 2.0 x 1.6, 2.5 x 2.0, 3.2 x 2.5, 5.0 x 3.2,
7.0 x 5.0 mm x mm
Instant samples with Time Machine II and field programmable
oscillators
RoHS and REACH compliant, Pb-free, Halogen-free and
Antimony-free
For AEC-Q100 oscillators, refer to SiT8924 and SiT8925
Electrical Specifications
Table 1. Electrical Characteristics
All Min and Max limits are specified over temperature and rated operating voltage with 15 pF output load unless otherwise stated. Typical values
are at 25°C and nominal supply voltage.
Parameters
Symbol
Min.
Typ.
Max.
Unit
Condition
Frequency Range
Output Frequency Range
f
1
–
110
MHz
F_stab
-20
–
+20
ppm
-25
–
+25
ppm
-30
–
+30
ppm
-50
–
+50
ppm
Refer to Table 13 for the exact list of supported frequencies
list of supported frequencies
Frequency Stability and Aging
Frequency Stability
Inclusive of Initial tolerance at 25°C, 1st year aging at 25°C, and
variations over operating temperature, rated power supply
voltage and load (15 pF ± 10%).
Operating Temperature Range
Operating Temperature Range
(ambient)
T_use
-40
–
+105
°C
Extended Industrial
-40
–
+125
°C
Automotive
Supply Voltage and Current Consumption
Supply Voltage
Current Consumption
OE Disable Current
Standby Current
Vdd
Idd
I_od
I_std
1.62
1.8
1.98
V
2.25
2.5
2.75
V
2.52
2.8
3.08
V
2.7
3.0
3.3
V
2.97
3.3
3.63
V
2.25
–
3.63
V
–
3.8
4.7
mA
No load condition, f = 20 MHz, Vdd = 2.8V, 3.0V or 3.3V
–
3.6
4.5
mA
No load condition, f = 20 MHz, Vdd = 2.5V
–
3.5
4.5
mA
No load condition, f = 20 MHz, Vdd = 1.8V
–
–
4.5
mA
Vdd = 2.5V to 3.3V, OE = Low, Output in high Z state.
–
–
4.3
mA
Vdd = 1.8V, OE = Low, Output in high Z state.
–
2.6
8.5
A
Vdd = 2.8V to 3.3V, ST = Low, Output is weakly pulled down
–
1.4
5.5
A
Vdd = 2.5V, ST = Low, Output is weakly pulled down
0.6
4.0
A
Vdd = 1.8V, ST = Low, Output is weakly pulled down
–
LVCMOS Output Characteristics
Duty Cycle
Rise/Fall Time
DC
45
–
55
%
Tr, Tf
–
1.0
2.0
ns
All Vdds
Vdd = 2.5V, 2.8V, 3.0V or 3.3V, 20% - 80%
–
1.3
2.5
ns
Vdd =1.8V, 20% - 80%
Vdd = 2.25V - 3.63V, 20% - 80%
–
1.0
3
ns
Output High Voltage
VOH
90%
–
–
Vdd
IOH = -4 mA (Vdd = 3.0V or 3.3V)
IOH = -3 mA (Vdd = 2.8V or 2.5V)
IOH = -2 mA (Vdd = 1.8V)
Output Low Voltage
VOL
–
–
10%
Vdd
IOL = 4 mA (Vdd = 3.0V or 3.3V)
IOL = 3 mA (Vdd = 2.8V or 2.5V)
IOL = 2 mA (Vdd = 1.8V)
SiTime Corporation
Rev. 1.01
990 Almanor Avenue, Sunnyvale, CA 94085
(408) 328-4400
www.sitime.com
Revised June 18, 2015
SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Table 1. Electrical Characteristics (continued)
Parameters
Symbol
Min.
Typ.
Max.
Unit
Condition
Input Characteristics
Input High Voltage
VIH
70%
–
–
Vdd
Input Low Voltage
VIL
–
–
30%
Vdd
Pin 1, OE or ST
Input Pull-up Impedence
Z_in
50
87
150
k
Pin 1, OE logic high or logic low, or ST logic high
–
–
M
Pin 1, ST logic low
2
Pin 1, OE or ST
Startup and Resume Timing
Startup Time
T_start
–
–
5
ms
Measured from the time Vdd reaches its rated minimum value
T_oe
–
–
130
ns
T_resume
–
–
5
ms
f = 110 MHz. For other frequencies, T_oe = 100 ns + 3 * clock
periods
Measured from the time ST pin crosses 50% threshold
Enable/Disable Time
Resume Time
Jitter
RMS Period Jitter
T_jitt
Peak-to-peak Period Jitter
T_pk
RMS Phase Jitter (random)
T_phj
–
1.6
2.5
ps
f = 75MHz, Vdd = 2.5V, 2.8V, 3.0V or 3.3V
–
1.9
3
ps
f = 75MHz, Vdd = 1.8V
–
12
20
ps
f = 75MHz, Vdd = 2.5V, 2.8V, 3.0V or 3.3V
–
14
25
ps
f = 75MHz,Vdd = 1.8V
–
0.5
0.8
ps
f = 75MHz, Integration bandwidth = 900 kHz to 7.5 MHz
–
1.3
2
ps
f = 75MHz, Integration bandwidth = 12 kHz to 20 MHz
Table 2. Pin Description
Pin
1
Symbol
OE/ ST/NC
Top View
Functionality
Output
Enable
H[1]: specified frequency output
L: output is high impedance. Only output driver is disabled.
Standby
H[1]: specified frequency output
L: output is low (weak pull down). Device goes to sleep mode. Supply
current reduces to I_std.
No Connect
Any voltage between 0 and Vdd or Open[1]: Specified frequency
output. Pin 1 has no function.
2
GND
Power
Electrical ground
3
OUT
Output
Oscillator output
4
VDD
Power
Power supply voltage[2]
OE/ST/NC
1
4
VDD
GND
2
3
OUT
Figure 1. Pin Assignments
Notes:
1. In OE or ST mode, a pull-up resistor of 10 kΩ or less is recommended if pin 1 is not externally driven.
If pin 1 needs to be left floating, use the NC option.
2. A capacitor of value 0.1 µF or higher between Vdd and GND is required.
Rev. 1.01
Page 2 of 13
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
N
Table 3. Absolute Maximum Limits
Attempted operation outside the absolute maximum ratings of the part may cause permanent damage to the part. Actual performance of the IC is only guaranteed within the operational specifications, not at absolute maximum ratings.
Min.
Max.
Unit
Storage Temperature
Parameter
-65
150
°C
Vdd
-0.5
4
V
Electrostatic Discharge
–
2000
V
Soldering Temperature (follow standard Pb free soldering guidelines)
–
260
°C
Junction Temperature[3]
–
150
°C
Note:
3. Exceeding this temperature for extended period of time may damage the device.
Table 4. Thermal Consideration[4]
JA, 4 Layer Board
JA, 2 Layer Board
JC, Bottom
7050
142
273
30
5032
97
199
24
3225
109
212
27
2520
117
222
26
2016
152
252
36
(°C/W)
Package
(°C/W)
(°C/W)
Note:
4. Refer to JESD51-7 for JA and JC definitions, and reference layout used to determine the JA and JC values in the above table.
Table 5. Maximum Operating Junction Temperature[5]
Max Operating Temperature (ambient)
Maximum Operating Junction Temperature
105°C
115°C
125°C
135°C
Note:
5. Datasheet specifications are not guaranteed if junction temperature exceeds the maximum operating junction temperature.
Table 6. Environmental Compliance
Parameter
Condition/Test Method
Mechanical Shock
MIL-STD-883F, Method 2002
Mechanical Vibration
MIL-STD-883F, Method 2007
Temperature Cycle
JESD22, Method A104
Solderability
MIL-STD-883F, Method 2003
Moisture Sensitivity Level
MSL1 @ 260°C
Rev. 1.01
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Test Circuit and Waveform[6]
Vdd
Vout
0.1µF
tr
3
4
Power
Supply
Test
Point
1
tf
80% Vdd
15pF
(including probe
and fixture
capacitance)
2
50%
20% Vdd
High Pulse
(TH)
Low Pulse
(TL)
Period
Vdd
1k
OE/ST Function
Figure 2. Test Circuit
Figure 3. Waveform
Note:
6. Duty Cycle is computed as Duty Cycle = TH/Period.
Timing Diagrams
Vdd
90% Vdd
Vdd
T_start
Pin 4 Voltage
50% Vdd
T_resume
ST Voltage
[7]
No Glitch
during start up
CLK Output
CLK Output
HZ
HZ
T_start: Time to start from power-off
T_resume: Time to resume from ST
Figure 4. Startup Timing (OE/ST Mode)
Figure 5. Standby Resume Timing (ST Mode Only)
u
Vdd
Vdd
OE Voltage
50% Vdd
OE Voltage
50% Vdd
T_oe
T_oe
CLK Output
CLK Output
HZ
HZ
T_oe: Time to put the output in High Z mode
T_oe: Time to re-enable the clock output
Figure 6. OE Enable Timing (OE Mode Only)
Figure 7. OE Disable Timing (OE Mode Only)
Note:
7. SiT8918 has “no runt” pulses and “no glitch” output during startup or resume.
Rev. 1.01
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Performance Plots[8]
1.8 V
2.5 V
2.8 V
3V
3.3 V
6.0
DUT1
DUT2
DUT3
DUT4
DUT5
DUT6
DUT7
DUT8
DUT9
DUT10
DUT11
DUT12
DUT13
DUT14
DUT15
DUT16
DUT17
DUT18
DUT19
DUT20
25
5.5
20
15
Frequency (ppm)
Idd (mA)
5.0
4.5
4.0
3.5
10
5
0
-5
-10
-15
-20
3.0
0
20
40
60
80
-25
100
‐55
‐35
‐15
Frequency (MHz)
Figure 8. Idd vs Frequency
1.8 V
2.5 V
2.8 V
3.0 V
25
45
65
85
105
125
Figure 9. Frequency vs Temperature
3.3 V
1.8 V
2.5 V
2.8 V
3.0 V
3.3 V
55
4.0
54
3.5
53
3.0
52
Duty cycle (%)
RMS period jitter (ps)
5
Temperature (°C)
2.5
2.0
1.5
1.0
51
50
49
48
47
0.5
46
0.0
0
20
40
60
80
45
100
0
Frequency (MHz)
2.8 V
3.0 V
3.3 V
1.8 V
2.5
2.5
2.0
2.0
1.5
1.0
80
100
2.5 V
2.8 V
20
40
3.0 V
3.3 V
1.5
1.0
0.5
0.5
0.0
0.0
-40
-20
0
20
40
60
80
100
-40
120
Temperature (°C)
-20
0
60
80
100
120
Temperature (°C)
Figure 12. 20%-80% Rise Time vs Temperature
Rev. 1.01
60
Figure 11. Duty Cycle vs Frequency
Fall time (ns)
Rise time (ns)
2.5 V
40
Frequency (MHz)
Figure 10. RMS Period Jitter vs Frequency
1.8 V
20
Figure 13. 20%-80% Fall Time vs Temperature
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Performance Plots[8]
1.8 V
2.5 V
2.8 V
3.0 V
3.3 V
1.8 V
2.5 V
2.8 V
3.0 V
3.3 V
1.0
2.0
1.9
0.9
1.8
0.8
1.6
IPJ (ps)
IPJ (ps)
1.7
1.5
1.4
1.3
0.7
0.6
0.5
1.2
0.4
1.1
1.0
0.3
10
20
30
40
50
60
70
80
90
100
110
10
Frequency (MHz)
20
30
40
50
60
70
80
90
100
110
Frequency (MHz)
Figure 14. RMS Integrated Phase Jitter Random
(12k to 20 MHz) vs Frequency[9]
Figure 15. RMS Integrated Phase Jitter Random
(900 kHz to 20 MHz) vs Frequency[9]
Notes:
8. All plots are measured with 15 pF load at room temperature, unless otherwise stated.
9. Phase noise plots are measured with Agilent E5052B signal source analyzer. Integration range is 12 kHz to 5 MHz for carrier frequencies up to 40 MHz.
Rev. 1.01
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Programmable Drive Strength
The SiT8918 includes a programmable drive strength feature
to provide a simple, flexible tool to optimize the clock rise/fall
time for specific applications. Benefits from the programmable
drive strength feature are:
• Improves system radiated electromagnetic interference
(EMI) by slowing down the clock rise/fall time
• Improves the downstream clock receiver’s (RX) jitter by decreasing (speeding up) the clock rise/fall time.
• Ability to drive large capacitive loads while maintaining full
swing with sharp edge rates.
For more detailed information about rise/fall time control and
drive strength selection, see the SiTime Applications Note
section; http://www.sitime.com/support/application-notes.
EMI Reduction by Slowing Rise/Fall Time
Figure 16 shows the harmonic power reduction as the rise/fall
times are increased (slowed down). The rise/fall times are
expressed as a ratio of the clock period. For the ratio of 0.05,
the signal is very close to a square wave. For the ratio of 0.45,
the rise/fall times are very close to near-triangular waveform.
These results, for example, show that the 11th clock harmonic
can be reduced by 35 dB if the rise/fall edge is increased from
5% of the period to 45% of the period.
trise=0.05
0
Harmonic amplitude (dB)
SiT8918 Drive Strength Selection
Tables 7 through 11 define the rise/fall time for a given capacitive load and supply voltage.
1. Select the table that matches the SiT8918 nominal supply
voltage (1.8V, 2.5V, 2.8V, 3.0V, 3.3V).
2. Select the capacitive load column that matches the application requirement (5 pF to 60 pF)
3. Under the capacitive load column, select the desired
rise/fall times.
4. The left-most column represents the part number code for
the corresponding drive strength.
5. Add the drive strength code to the part number for ordering
purposes.
Calculating Maximum Frequency
Based on the rise and fall time data given in Tables 7 through
11, the maximum frequency the oscillator can operate with
guaranteed full swing of the output voltage over temperature
as follows:
trise=0.1
trise=0.15
trise=0.2
10
M a x F re q u e n c y =
trise=0.25
trise=0.3
trise=0.35
trise=0.4
trise=0.45
-10
-20
1
5 x T rf_ 2 0 /8 0
where Trf_20/80 is the typical value for 20%-80% rise/fall
time.
-30
-40
Example 1
-50
-60
Calculate fMAX for the following condition:
-70
-80
The SiT8918 can support up to 60 pF or higher in maximum
capacitive loads with drive strength settings. Refer to the
Rise/Tall Time Tables (Table 7 to 11) to determine the proper
drive strength for the desired combination of output load vs.
rise/fall time
1
3
5
7
9
11
Harm onic num ber
Figure 16. Harmonic EMI reduction as a Function of
Slower Rise/Fall Time
Jitter Reduction with Faster Rise/Fall Time
Power supply noise can be a source of jitter for the
downstream chipset. One way to reduce this jitter is to speed
up the rise/fall time of the input clock. Some chipsets may also
require faster rise/fall time in order to reduce their sensitivity to
this type of jitter. Refer to the Rise/Fall Time Tables (Table 7 to
Table 11) to determine the proper drive strength.
• Vdd = 1.8V (Table 7)
• Capacitive Load: 30 pF
• Desired Tr/f time = 3 ns (rise/fall time part number code = E)
Part number for the above example:
SiT8918BE12-18E-66.666660
Drive strength code is inserted here. Default setting is “-”
High Output Load Capability
The rise/fall time of the input clock varies as a function of the
actual capacitive load the clock drives. At any given drive
strength, the rise/fall time becomes slower as the output load
increases. As an example, for a 3.3V SiT8918 device with
default drive strength setting, the typical rise/fall time is 1ns for
15 pF output load. The typical rise/fall time slows down to 2.6
ns when the output load increases to 45 pF. One can choose
to speed up the rise/fall time to 1.83ns by then increasing the
drive strength setting on the SiT8918.
Rev. 1.01
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Rise/Fall Time (20% to 80%) vs CLOAD Tables
Table 7. Vdd = 1.8V Rise/Fall Times for Specific CLOAD
Table 8. Vdd = 2.5V Rise/Fall Times for Specific CLOAD
Rise/Fall Time Typ (ns)
Rise/Fall Time Typ (ns)
Drive Strength \ CLOAD
5 pF
15 pF
30 pF
45 pF
60 pF
Drive Strength \ CLOAD
5 pF
15 pF
30 pF
45 pF
60 pF
L
A
R
B
T
E
U
F or "‐": default
6.16
3.19
2.11
1.65
0.93
0.78
0.70
0.65
11.61
6.35
4.31
3.23
1.91
1.66
1.48
1.30
22.00
11.00
7.65
5.79
3.32
2.94
2.64
2.40
31.27
16.01
10.77
8.18
4.66
4.09
3.68
3.35
39.91
21.52
14.47
11.08
6.48
5.74
5.09
4.56
L
A
R
B
T
E or "‐": default
U
F
4.13
2.11
1.45
1.09
0.62
8.25
4.27
2.81
2.20
1.28
12.82
7.64
5.16
3.88
2.27
21.45
11.20
7.65
5.86
3.51
27.79
14.49
9.88
7.57
4.45
0.54
0.43
0.34
1.00
0.96
0.88
2.01
1.81
1.64
3.10
2.79
2.54
4.01
3.65
3.32
Table 9. Vdd = 2.8V Rise/Fall Times for Specific CLOAD
Table 10. Vdd = 3.0V Rise/Fall Times for Specific CLOAD
Rise/Fall Time Typ (ns)
Rise/Fall Time Typ (ns)
Drive Strength \ CLOAD
5 pF
15 pF
30 pF
45 pF
60 pF
Drive Strength \ CLOAD
5 pF
15 pF
30 pF
45 pF
60 pF
L
A
R
B
T
3.77
1.94
1.29
0.97
0.55
7.54
3.90
2.57
2.00
1.12
12.28
7.03
4.72
3.54
2.08
19.57
10.24
7.01
5.43
3.22
25.27
13.34
9.06
6.93
4.08
E or "‐": default
U
F
0.44
0.34
0.29
1.00
0.88
0.81
1.83
1.64
1.48
2.82
2.52
2.29
3.67
3.30
2.99
L
A
R
B
T or "‐": default
E
U
F
3.60
1.84
1.22
0.89
0.51
0.38
0.30
0.27
7.21
3.71
2.46
1.92
1.00
0.92
0.83
0.76
11.97
6.72
4.54
3.39
1.97
1.72
1.55
1.39
18.74
9.86
6.76
5.20
3.07
2.71
2.40
2.16
24.30
12.68
8.62
6.64
3.90
3.51
3.13
2.85
Table 11. Vdd = 3.3V Rise/Fall Times for Specific CLOAD
Rise/Fall Time Typ (ns)
Drive Strength \ CLOAD
5 pF
15 pF
30 pF
45 pF
60 pF
L
A
R
B
3.39
1.74
1.16
0.81
6.88
3.50
2.33
1.82
11.63
6.38
4.29
3.22
17.56
8.98
6.04
4.52
23.59
12.19
8.34
6.33
T or "‐": default
E
U
F
0.46
0.33
0.28
0.25
1.00
0.87
0.79
0.72
1.86
1.64
1.46
1.31
2.60
2.30
2.05
1.83
3.84
3.35
2.93
2.61
Rev. 1.01
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SiT8918B
High Temperature Oscillator
The Smart Timing Choice
The Smart Timing Choice
Pin 1 Configuration Options (OE, ST, or NC)
Pin 1 of the SiT8918 can be factory-programmed to support
three modes: Output enable (OE), standby (ST) or No Connect
(NC). These modes can also be programmed with the Time
Machine using field programmable devices.
Output Enable (OE) Mode
In the OE mode, applying logic Low to the OE pin only disables
the output driver and puts it in Hi-Z mode. The core of the
device continues to operate normally. Power consumption is
reduced due to the inactivity of the output. When the OE pin is
pulled High, the output is typically enabled in