1 – 110 MHz, -55 to 125°C, Endura™ Series Oscillator
Features
Applications
Best acceleration sensitivity of 0.1 ppb/g
Any frequencies between 1 MHz and 110 MHz accurate to
6 decimal places
Extended temperature range (-55°C to 125°C)
Excellent total frequency stability as low as ±20 ppm
Supply voltage of 1.8V or 2.25V to 3.63V
Low power consumption of 3.8 mA typical at 1.8V
Standby mode for longer battery life
LVCMOS/LVTTL compatible output
AEC-Q100 qualified
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
RoHS and REACH compliant, Pb-free, Halogen-free and
Antimony-free
Contact SiTime
for up-screening and LAT programs
Avionics systems
Field communication systems
Telemetry applications
Electrical Characteristics
Table 1. Electrical Characteristics
[1,2]
All Min and Max limits are specified over temperature and rated operating voltage with 15 pF output load unless otherwise sta ted.
Typical values are at 25°C and nominal supply voltage.
Parameters
Output Frequency Range
Symbol
f
Min.
1
Typ.
–
–
–
–
–
–
–
–
–
–
Max.
110
Unit
MHz
Condition
Refer to Tables 13 to 15 for a
list supported frequencies
Frequency Range
Frequency Stability and Aging
Frequency Stability
F_stab
-20
-25
-30
-50
+20
+25
+30
+50
ppm
ppm
ppm
ppm
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
-40
-40
-55
–
+85
+105
+125
+125
°C
°C
°C
°C
AEC-Q100 Grade 3
AEC-Q100 Grade 2
AEC-Q100 Grade 1
Extended cold AEC-Q100 Grade1
Rugged Characteristics
Acceleration (g) sensitivity,
Gamma Vector
F_g
0.1
ppb/g
Low sensitivity grade; total gamma over 3 axes; 15 Hz to 2 kHz;
MIL-PRF-55310, computed per section 4.8.18.3.1
Supply Voltage and Current Consumption
Supply Voltage
Vdd
1.62
2.25
Current Consumption
Idd
–
–
OE Disable Current
I_od
–
–
Standby Current
I_std
–
–
–
1.8
–
4.0
3.8
–
–
2.6
1.4
0.6
1.98
3.63
4.8
4.5
4.5
4.3
–
–
–
V
V
mA
mA
mA
mA
A
A
A
All voltages between 2.25V and 3.63V including 2.5V, 2.8V, 3.0V
and 3.3V are supported
No load condition, f = 20 MHz, Vdd = 2.25V to 3.63V
No load condition, f = 20 MHz, Vdd = 1.8V
Vdd = 2.5V to 3.3V, OE = Low, Output in high Z state
Vdd = 1.8V, OE = Low, Output in high Z state
Vdd = 2.8V to 3.3V,
ST
= Low, Output is weakly pulled down
Vdd = 2.5V,
ST
= Low, Output is weakly pulled down
Vdd = 1.8V,
ST
= Low, Output is weakly pulled down
Rev 0.5
July 23, 2019
www.sitime.com
SiT8944B
1 – 110 MHz, -55 to 125°C, Endura™ Series Oscillator
Table 1. Electrical Characteristics
[1,2]
(continued)
Parameters
Duty Cycle
Rise/Fall Time
Symbol
DC
Tr, Tf
Min.
45
–
–
Output High Voltage
VOH
90%
Typ.
–
1.5
1.3
–
Max.
55
3
2.5
–
Unit
%
ns
ns
Vdd
All Vdd levels
PRELIMINARY
Condition
LVCMOS Output Characteristics
Vdd = 2.25V - 3.63V, 20% - 80%
Vdd = 1.8V, 20% - 80%
IOH = -4 mA (Vdd = 3.0V or 3.3V)
IOH = -3 mA (Vdd = 2.8V and Vdd = 2.5V)
IOH = -2 mA (Vdd = 1.8V)
IOL = 4 mA (Vdd = 3.0V or 3.3V)
IOL = 3 mA (Vdd = 2.8V and Vdd = 2.5V)
IOL = 2 mA (Vdd = 1.8V)
Pin 1, OE or
ST
Pin 1, OE or
ST
Pin 1, OE logic high or logic low, or
ST
logic high
Pin 1,
ST
logic low
Output Low Voltage
VOL
–
–
10%
Vdd
Input High Voltage
Input Low Voltage
Input Pull-up Impedance
VIH
VIL
Z_in
70%
–
–
2
–
–
100
–
Input Characteristics
–
Vdd
30%
–
–
Vdd
k
M
Startup and Resume Timing
Startup Time
Enable/Disable Time
Resume Time
T_start
T_oe
T_resume
–
–
–
–
–
–
5.5
130
5
Jitter
RMS Period Jitter
T_jitt
–
–
RMS Phase Jitter (random)
T_phj
–
–
1.6
1.9
0.5
1.3
2.5
3.0
–
–
ps
ps
ps
ps
f = 75 MHz, 2.25V to 3.63V
f = 75 MHz, 1.8V
f = 75 MHz, Integration bandwidth = 900 kHz to 7.5 MHz
f = 75 MHz, Integration bandwidth = 12 kHz to 20 MHz
ms
ns
ms
Measured from the time Vdd reaches its rated minimum value
f = 110 MHz. For other frequencies, T_oe = 100 ns + 3 * cycles
Measured from the time
ST
pin crosses 50% threshold
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 Characteristic 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
[3]
Functionality
Output Enable
H : specified frequency output
L: output is high impedance. Only output driver is disabled.
H
[3]
: specified frequency output
L: output is low (weak pull down). Device goes to sleep mode.
Supply current reduces to I_std.
Any voltage between 0 and Vdd or Open
[3]
: Specified frequency
output. Pin 1 has no function.
Electrical ground
[4]
Oscillator output
Power supply voltage
[4]
Top View
OE/ST/NC
1
4
VDD
1
OE/
ST
/NC
Standby
No Connect
GND
2
3
OUT
2
3
4
Notes:
GND
OUT
VDD
Power
Output
Power
Figure 1. Pin Assignments
3. 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.
4. A capacitor of value 0.1 µF or higher between Vdd and GND is required.
Rev 0.5
Page 2 of 15
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SiT8944B
1 – 110 MHz, -55 to 125°C, Endura™ Series Oscillator
Table 3. Absolute Maximum Limits
PRELIMINARY
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.
Parameter
Storage Temperature
Vdd
Electrostatic Discharge
Soldering Temperature (follow standard Pb free soldering guidelines)
Junction Temperature
[5]
Min.
-65
-0.5
–
–
–
Max.
150
4
2000
260
150
Unit
°C
V
V
°C
°C
Note:
5. Exceeding this temperature for extended period of time may damage the device.
Table 4. Thermal Consideration
[6]
Package
7050
5032
3225
2520
2016
JA, 4 Layer Board
(°C/W)
142
97
109
117
152
JA, 2 Layer Board
(°C/W)
273
199
212
222
252
JC, Bottom
(°C/W)
30
24
27
26
36
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)
85°C
105°C
125°C
Maximum Operating Junction Temperature
95°C
115°C
135°C
Note:
7. Datasheet specifications are not guaranteed if junction temperature exceeds the maximum operating junction temperature.
Table 6. Environmental Compliance
Parameter
Mechanical Shock
Mechanical Vibration
Temperature Cycle
Solderability
Moisture Sensitivity Level
Condition/Test Method
MIL-STD-883F, Method 2002
MIL-STD-883F, Method 2007
JESD22, Method A104
MIL-STD-883F, Method 2003
MSL1 @ 260°C
Rev 0.5
Page 3 of 15
www.sitime.com
SiT8944B
1 – 110 MHz, -55 to 125°C, Endura™ Series Oscillator
Test Circuit and Waveform
Vdd
Vout
Test
Point
PRELIMINARY
tr
4
Power
Supply
0.1µF
3
tf
80% Vdd
1
2
15pF
(including probe
and fixture
capacitance)
50%
20% Vdd
High Pulse
(TH)
Period
Low Pulse
(TL)
Vdd
OE/NC Function
1k
Figure 2. Test Circuit
[8]
Note:
8. Duty Cycle is computed as Duty Cycle = TH/Period.
Figure 3. Waveform
[8]
Timing Diagrams
90% Vdd
Vdd
Vdd
50% Vdd
Pin 4 Voltage
T_start
No Glitch
during start up
ST Voltage
T_resume
CLK Output
HZ
CLK Output
HZ
T_start: Time to start from power-off
T_resume: Time to resume from ST
Figure 4. Startup Timing (OE/
ST
Mode)
[9]
Vdd
50% Vdd
T_oe
OE Voltage
Figure 5. Standby Resume Timing (
ST
Mode Only)
Vdd
OE Voltage
50% Vdd
T_oe
CLK Output
HZ
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)
Note:
9. SiT8944 has “no runt” pulses and “no glitch” output during startup or resume.
Figure 7. OE Disable Timing (OE Mode Only)
Rev 0.5
Page 4 of 15
www.sitime.com
SiT8944B
1 – 110 MHz, -55 to 125°C, Endura™ Series Oscillator
///////////////24MHZ时钟设置//////////////////////////////////////////////////////////////
UCSCTL3 |=SELREF__REFOCLK;
__bis_SR_register(SCG0); //disable the FLL control ......
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