SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Features
Applications
Frequencies between 115.194001 MHz to 137 MHz accurate to 6
decimal places
Industrial, medical, avionics and other high temperature applications
Operating temperature from -40°C to 125°C. For -55°C option, refer
to SiT2020 and SiT2021
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 5mA typical at 1.8V
LVCMOS/LVTTL compatible output
5-pin SOT23-5 package: 2.9mm x 2.8mm
RoHS and REACH compliant, Pb-free, Halogen-free and
Antimony-free
For AEC-Q100 clock generators, refer to SiT2024 and SiT2025
Electrical Specifications
Table 1. Electrical Characteristics[1,2]
Parameters
Symbol
Min.
Typ.
Max.
Unit
Condition
Frequency Range
Output Frequency Range
f
115.194001
–
137
MHz
F_stab
-20
–
+20
ppm
-25
–
+25
ppm
-30
–
+30
ppm
-50
–
+50
ppm
Refer to Table 14 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
–
6.2
8
mA
No load condition, f = 125 MHz, Vdd = 2.8V, 3.0V or 3.3V
–
5.4
7
mA
No load condition, f = 125 MHz, Vdd = 2.5V
–
4.8
6
mA
No load condition, f = 125 MHz, Vdd = 1.8V
–
–
4.8
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
3.5
A
Vdd = 1.8V, ST = Low, Output is Weakly Pulled Down
LVCMOS Output Characteristics
Duty Cycle
Rise/Fall Time
DC
45
–
55
%
All Vdds
Tr, Tf
–
1.0
2.0
ns
Vdd = 2.5V, 2.8V, 3.0V or 3.3V, 20% - 80%
–
1.3
2.5
ns
Vdd = 1.8V, 20% - 80%
–
1.0
3
ns
Vdd = 2.25V - 3.63V, 20% - 80%
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. 1.0
990 Almanor Avenue, Sunnyvale, CA 94085
(408) 328-4400
www.sitime.com
Revised October 16, 2014
SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Table 1. Electrical Characteristics[1,2] (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 90% of final value
T_oe
–
–
130
ns
T_resume
–
–
5
ms
f = 115.194001 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 = 125 MHz, Vdd = 2.5V, 2.8V, 3.0V or 3.3V
–
1.8
3
ps
f = 125 MHz, Vdd = 1.8V
–
12
20
ps
f = 125 MHz, Vdd = 2.5V, 2.8V, 3.0V or 3.3V
–
14
30
ps
f = 125 MHz, Vdd = 1.8V
–
0.5
0.8
ps
f = 125 MHz, Integration bandwidth = 900 kHz to 7.5 MHz
–
1.3
2
ps
f = 125 MHz, Integration bandwidth = 12 kHz to 20 MHz
Notes:
1. All electrical specifications in the above table are specified with 15 pF output load and for all Vdd(s) unless otherwise stated.
2. The typical value of any parameter in the Electrical Characteristics table is specified for the nominal value of the highest voltage option for that parameter and at
25 °C temperature.
Table 2. Pin Description
Pin
Symbol
1
GND
Power
2
NC
No Connect
3
OE/ ST/NC
Electrical ground
OE/ST/NC NC
No connect
Output
Enable
H[4]: specified frequency output
L: output is high impedance. Only output driver is disabled.
Standby
H or Open[4]: specified frequency output
L: output is low (weak pull down). Device goes to sleep mode. Supply
current reduces to I_std.
No Connect
3
2
GND
1
Any voltage between 0 and Vdd or Open[4]: Specified frequency
output. Pin 3 has no function.
4
VDD
Power
Power supply voltage[3]
5
OUT
Output
Oscillator output
Notes:
3. A capacitor of value 0.1 µF or higher between Vdd and GND is required.
4. In OE or ST mode, a pull-up resistor of 10 kΩ or less is recommended if pin 3 is not externally driven.
If pin 3 needs to be left floating, use the NC option.
Rev. 1.0
Top View
Functionality
[3]
Page 2 of 12
4
5
VDD
OUT
Figure 1. Pin Assignments
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
N
Table 3. Absolute Maximum Limits
Attempted operation outside the absolute maximum ratings 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[5]
–
150
°C
Note:
5. Exceeding this temperature for extended period of time may damage the device.
Table 4. Thermal Consideration[6]
JA, 4 Layer Board
JC, Bottom
421
175
(°C/W)
Package
SOT23-5
(°C/W)
Note:
6. Refer to JESD51 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[7]
Max Operating Temperature (ambient)
Maximum Operating Junction Temperature
105°C
115°C
125°C
135°C
Note:
7. 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. 1.0
Page 3 of 12
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Test Circuit and Waveform[8]
Vout
Test
Point
Vdd
Tr
5
15pF
(including probe
and fixture
capacitance)
4
1
2
3
Power
Supply
0.1µF
Tf
80% Vdd
50%
20% Vdd
High Pulse
(TH)
Low Pulse
(TL)
Period
Vdd
1k
OE/ST Function
Figure 3. Output Waveform
Figure 2. Test Circuit
Note:
8. Duty Cycle is computed as Duty Cycle = TH/Period.
Timing Diagrams
90% Vdd
Vdd
Vdd
50% Vdd
Pin 4 Voltage
T_start
[9]
No Glitch
during start up
ST Voltage
T_resume
CLK Output
CLK Output
T_resume: Time to resume from ST
T_start: Time to start from power-off
Figure 4. Startup Timing (OE/ST Mode)
Figure 5. Standby Resume Timing (ST Mode Only)
u
Vdd
Vdd
50% Vdd
OE Voltage
OE Voltage
50% Vdd
T_oe
T_oe
CLK Output
CLK Output
HZ
T_oe: Time to re-enable the clock output
T_oe: Time to put the output in High Z mode
Figure 6. OE Enable Timing (OE Mode Only)
Figure 7. OE Disable Timing (OE Mode Only)
Note:
9. SiT2019 has “no runt” pulses and “no glitch” output during startup or resume.
Rev. 1.0
Page 4 of 12
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Performance Plots[10]
1.8 V
2.5 V
2.8 V
3.0 V
3.3 V
DUT 2
DUT 3
DUT 4
DUT 5
DUT 6
DUT 7
DUT 8
DUT 9
DUT 10
25
6.5
20
Frequency (ppm)
6.0
5.5
Idd (mA)
DUT 1
5.0
4.5
4.0
15
) 10
m
p 5
p
(y
c
n 0
e
u ‐5
q
e
Fr ‐10
‐15
3.5
‐20
‐25
3.0
115
120
125
130
135
‐40
‐20
0
Frequency (MHz)
2.8 V
3.0 V
3.3 V
1.8 V
4.0
55
3.5
54
2.5
2.0
1.5
1.0
100
120
2.5 V
2.8 V
3.0 V
3.3 V
52
51
50
49
48
47
0.5
46
115
120
125
130
45
115
135
120
125
Figure 10. RMS Period Jitter vs Frequency
1.8 V
2.5 V
2.8 V
130
135
Frequency (MHz)
Frequency (MHz)
3.0 V
Figure 11. Duty Cycle vs Frequency
3.3 V
1.8 V
2.5
2.5
2.0
2.0
Fall time (ns)
Rise time (ns)
80
53
3.0
0.0
1.5
1.0
2.5 V
2.8 V
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
-20
0
20
40
60
80
100
120
Temperature (°C)
Temperature (°C)
Figure 12. 20%-80% Rise Time vs Temperature
(125 MHz Output)
Rev. 1.0
60
Figure 9. Frequency vs Temperature
Duty cycle (%)
RMS period jitter (ps)
2.5 V
40
Temperature (°C)
Figure 8. Idd vs Frequency
1.8 V
20
Temperature (°C)
Figure 13. 20%-80% Fall Time vs Temperature
(125 MHz Output)
Page 5 of 12
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Performance Plots[10]
1.8 V
2.5 V
2.8 V
3.0 V
3.3 V
1.8 V
2.0
2.5 V
2.8 V
3.0 V
3.3 V
1.0
0.9
1.8
IPJ (ps)
IPJ (ps)
0.8
1.6
1.4
1.2
1.0
115
0.7
0.6
0.5
120
125
130
0.4
115
135
120
125
130
135
Frequency (MHz)
Frequency (MHz)
Figure 14. RMS Integrated Phase Jitter Random
(12 kHz to 20 MHz) vs Frequency[11]
Figure 15. RMS Integrated Phase Jitter Random
(900 kHz to 7.5 MHz) vs Frequency[11]
Notes:
10. All plots are measured with 15 pF load at room temperature, unless otherwise stated.
11. Phase noise plots are measured with Agilent E5052B signal source analyzer.
Rev. 1.0
Page 6 of 12
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Programmable Drive Strength
The SiT2019 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 Application Notes
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)
SiT2019 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 SiT2019 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 30 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
can be calculated 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 SiT2019 can support up to 30 pF in maximum capacitive
loads with up to 3 additional 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 = 3.3V (Table 11)
• Capacitive Load: 30 pF
• Desired Tr/f time = 1.46 ns (rise/fall time part number code
= U)
Part number for the above example:
SiT2019AIU12-33E-136.986300
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 SiT2019 device with
default drive strength setting, the typical rise/fall time is
0.46 ns for 5 pF output load. The typical rise/fall time slows
down to 1 ns when the output load increases to 15 pF. One can
choose to speed up the rise/fall time to 0.72 ns by then
increasing the driven strength setting on the SiT2019 to “F.”
Rev. 1.0
Page 7 of 12
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
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 \ C LOAD
5 pF
15 pF
30 pF
Drive Strength \ C LOAD
5 pF
15 pF
30 pF
T
0.93
n/a
n/a
R
1.45
n/a
n/a
E
0.78
n/a
n/a
B
1.09
n/a
n/a
U
0.70
1.48
n/a
0.62
1.28
n/a
0.65
1.30
n/a
T
E
0.54
1.00
n/a
0.43
0.96
n/a
0.34
0.88
n/a
F or "-": default
U or "-": default
F
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 \ C LOAD
5 pF
15 pF
30 pF
Drive Strength \ CLOAD
5 pF
15 pF
30 pF
R
1.29
n/a
n/a
R
1.22
n/a
n/a
B
0.97
n/a
n/a
n/a
n/a
0.55
1.12
n/a
B
T or "-": default
0.89
T
E
0.51
1.00
n/a
0.44
1.00
n/a
E
0.38
0.92
n/a
0.34
0.88
n/a
0.83
n/a
0.81
1.48
U
F
0.30
0.29
0.27
0.76
1.39
U or "-": default
F
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
R
1.16
n/a
n/a
B
T or "-": default
0.81
n/a
n/a
0.46
1.00
n/a
E
0.33
0.87
n/a
U
F
0.28
0.79
1.46
0.25
0.72
1.31
Note:
12. “n/a” in Table 7 to Table 11 indicates that the resulting rise/fall time from the respective combination of the drive strength and output load does not provide
rail-to-rail swing and is not available.
Rev. 1.0
Page 8 of 12
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SiT2019
High Frequency, High Temp, One-Output Clock Generator
The Smart Timing Choice
The Smart Timing Choice
Pin 3 Configuration Options (OE, ST, or NC)
Pin 3 of the SiT2019 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.
In addition, the SiT2019 has “no runt” pulses, and “no glitch”
output during startup or resume as shown in the waveform
captures in Figure 17 and Figure 18.
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