32.768 kHz ±5, ±10, ±20 ppm frequency stability options over temp
World’s smallest TCXO in a 1.5 x 0.8 mm CSP
Operating temperature ranges:
• 0°C to +70°C
• -40°C to +85°C
Smart Meters (AMR)
Health and Wellness Monitors
Pulse-per-Second (pps) Timekeeping
RTC Reference Clock
Ultra-low power: <1 µA
Vdd supply range: 1.5V to 3.63V
Improved stability reduces system power with fewer network
timekeeping updates
NanoDrive™ programmable output swing for lowest power and direct
XTAL SoC input interface
Internal filtering eliminates external Vdd bypass cap and saves space
Pb-free, RoHS and REACH compliant
Electrical Characteristics
Parameter
Output Frequency
Frequency Stability Over
Temperature
[1]
(without Initial Offset
[2]
)
Frequency Stability Over
Temperature
(with Initial Offset
[2]
)
Frequency Stability vs Voltage
First Year Frequency Aging
Symbol
Fout
-5.0
F_stab
-10
-20
-10
F_stab
-13
-22
F_vdd
F_aging
-0.75
-1.5
-1.0
Min.
Typ.
32.768
5.0
10
20
10
13
22
0.75
1.5
1.0
ppm
ppm
ppm
µs
pp
ns
RMS
3.63
0.99
1.52
100
180
Start-up Time at Power-up
t_start
300
350
380
ms
V
μA
ms
ppm
ppm
Max.
Unit
kHz
Stability part number code = E
Stability part number code = F
Stability part number code = 1
Stability part number code = E
Stability part number code = F
Stability part number code = 1
1.8V ±10%
1.5V – 3.63V
T
A
= 25°C, Vdd = 3.3V
81920 cycles (2.5 sec), 100 samples
Cycles = 10,000, T
A
= 25°C, Vdd = 1.5V – 3.63V
T
A
= -40°C to +85°C
T
A
= 25°C, Vdd = 1.8V, LVCMOS Output configuration, No Load
T
A
= -40°C to +85°C, Vdd = 1.5V – 3.63V, No Load
Vdd Ramp-Up 0 to 90% Vdd, T
A
= -40°C to +85°C
T
A
= -40°C +60°C, valid output
T
A
= +60°C to +70°C, valid output
T
A
= +70°C to +85°C, valid output
Condition
Frequency and Stability
Jitter Performance (T
A
= over temp)
Long Term Jitter
Period Jitter
35
2.5
Supply Voltage and Current Consumption
Operating Supply Voltage
Core Supply Current
[3]
Power-Supply Ramp
Vdd
Idd
t_Vdd_
Ramp
1.5
Notes:
1. No board level underfill. Measured as peak-to-peak/2. Inclusive of 3x-reflow and ±20% load variation. Tested with Agilent 53132A frequency counter. Due to the
low operating frequency, the gate time must be ≥100 ms to ensure an accurate frequency measurement.
2. Initial offset is defined as the frequency deviation from the ideal 32.768 kHz at room temperature, post reflow.
3. Core operating current does not include output driver operating current or load current. To derive total operating current (no load), add core operating current +
output driver operating current, which is a function of the output voltage swing. See the description titled,
Calculating Load Current.
SiTime Corporation
Rev 1.2
990 Almanor Avenue, Sunnyvale, CA 94085
(408) 328-4400
www.sitime.com
Revised November 10, 2014
SiT1552
Smallest (1.2mm
2
), Ultra-Low Power, 32.768 kHz MEMS TCXO
The Smart Timing Choice
The Smart Timing Choice
Electrical Characteristics
(continued)
Parameter
Commercial Temperature
Industrial Temperature
Symbol
Min.
0
-40
100
48
90%
10%
200
48
0.20 to
0.80
0.6 to
1.225
0.35 to
0.80
-0.055
0.055
52
Typ.
Max.
70
85
LVCMOS Output
Output Rise/Fall Time
Output Clock Duty Cycle
Output Voltage High
Output Voltage Low
Output Rise/Fall Time
Output Clock Duty Cycle
AC-coupled Programmable
Output Swing
DC-Biased Programmable
Output Voltage High Range
DC-Biased Programmable
Output Voltage Low Range
Programmable Output Voltage
Swing Tolerance
tr, tf
DC
VOH
VOL
tf, tf
DC
V_sw
VOH
VOL
200
50
52
ns
%
V
V
ns
%
V
V
V
V
SiT1552 does not internally AC-couple. This output description
is intended for a receiver that is AC-coupled.
Vdd: 1.5V – 3.63V, 10 pF Load, I
OH
/ I
OL
= ±0.2 μA
Vdd: 1.5V – 3.63V. I
OH
= -0.2 μA, 10 pF Load
Vdd: 1.5V – 3.63V. I
OL
= 0.2 μA, 10 pF Load
T
A
= -40°C to +85°C, Vdd = 1.5V to 3.63V.
Vdd: 1.5V – 3.63V. I
OH
= -1 μA, 15 pF Load
Vdd: 1.5V – 3.63V. I
OL
= 1 μA, 15 pF Load
30-70% (V
OL
/V
OH
), 10 pF Load
10-90% (Vdd), 15 pF Load
10-90% (Vdd), 5 pF Load, Vdd ≥ 1.62V
Unit
°C
°C
Condition
Operating Temperature Range
Op_Temp
NanoDrive™ Reduced Swing Output
Pin Configuration
CSP
Pin
1, 4
Symbol
GND
I/O
Power Supply
Ground
Functionality
Connect to ground. All GND pins must be connected to power supply ground. The GND pins
can be connected together, as long as both GND pins are connected ground.
Oscillator clock output. When interfacing to an MCU’s XTAL, the CLK Out is typically
connected to the receiving IC’s X IN pin. The SiT1552 oscillator output includes an internal
driver. As a result, the output swing and operation is not dependent on capacitive loading.
This makes the output much more flexible, layout independent, and robust under changing
environmental and manufacturing conditions.
Connect to power supply 1.5V ≤ Vdd ≤ 3.63V. Under normal operating conditions, Vdd does
not require external bypass/decoupling capacitor(s). For more information about the internal
power-supply filtering, see
Power-Supply Noise Immunity
section in the detailed description..
Contact factory for applications that require a wider operating supply voltage range.
2
CLK Out
OUT
3
Vdd
Power Supply
CSP Package (Top View)
GND
1
4
GND
CLK Out
2
3
Vdd
Rev. 1.2
Page 2 of 12
www.sitime.com
SiT1552
Smallest (1.2mm
2
), Ultra-Low Power, 32.768 kHz MEMS TCXO
The Smart Timing Choice
The Smart Timing Choice
System Block Diagram
MEMS Resonator
GND
Control
Temp
Control
Regulators
Vdd
Temp-to-Digital
Prog
Prog
NVM
GND
Sustaining
Amp
Ultra-low
Power
Frac-n
PLL
Divider
Driver
CLK Out
Figure 1.
Absolute Maximum
Attempted operation outside the absolute maximum ratings cause permanent damage to the part. Actual performance of the IC
is only guaranteed within the operational specifications, not at absolute maximum ratings.
Parameter
Continuous Power Supply Voltage Range (Vdd)
Short Duration Maximum Power Supply Voltage (Vdd)
Continuous Maximum Operating Temperature Range
Short Duration Maximum Operating Temperature Range
Human Body Model (HBM) ESD Protection
Charge-Device Model (CDM) ESD Protection
Machine Model (MM) ESD Protection
Latch-up Tolerance
Mechanical Shock Resistance
Mechanical Vibration Resistance
1508 CSP Junction Temperature
Storage Temperature
≤30 minutes
Vdd = 1.5V - 3.63V
Vdd = 1.5V - 3.63V, ≤30 mins
JESD22-A114
JESD22-A115
JESD22-C101
JESD78 Compliant
Mil 883, Method 2002
Mil 883, Method 2007
10,000
70
150
-65°C to 150°C
g
g
°C
Test Condition
Value
-0.5 to 3.63
4.0
105
125
3000
750
300
Unit
V
V
°C
°C
V
V
V
Rev. 1.2
Page 3 of 12
www.sitime.com
SiT1552
Description
Smallest (1.2mm
2
), Ultra-Low Power, 32.768 kHz MEMS TCXO
The Smart Timing Choice
The Smart Timing Choice
Start-up and Steady-State Supply Current
The SiT1552 TCXO starts-up to a valid output frequency
within 300 ms (180 ms typ). To ensure the device starts-up
within the specified limit, make sure the power-supply
ramps-up in approximately 10 - 20 ms (to within 90% of Vdd).
During initial power-up, the SiT1552 power-cycles internal
blocks, as shown in the power-supply start-up and steady
state plot in the
Typical Operating Curves
section. Power-up
and initialization is typically 200 ms, and during that time, the
peak supply current reaches 28 µA as the internal capacitors
are charged, then sequentially drops to its 990 nA
steady-state current. During steady-state operation, the
internal temperature compensation circuit turns on every 350
ms for a duration of approximately 10 ms.
The SiT1552 is an ultra-small and ultra-low power 32.768 kHz
TCXO optimized for battery-powered applications. SiTime’s
silicon MEMS technology enables the first 32 kHz TCXO in the
world’s smallest footprint and chip-scale packaging (CSP).
Typical core supply current is only 1 µA. And unlike standard
oscillators, the SiT1552 features NanoDrive™, a factory
programmable output that reduces the voltage swing to
minimize power.
SiTime’s MEMS oscillators consist of MEMS resonators and
a programmable analog circuit. Our MEMS resonators are
built with SiTime’s unique MEMS First™ process. A key
manufacturing step is EpiSeal™ during which the MEMS
resonator is annealed with temperatures over 1000°C.
EpiSeal creates an extremely strong, clean, vacuum chamber
that encapsulates the MEMS resonator and ensures the best
performance and reliability. During EpiSeal, a poly silicon cap
is grown on top of the resonator cavity, which eliminates the
need for additional cap wafers or other exotic packaging. As
a result, SiTime’s MEMS resonator die can be used like any
other semiconductor die. One unique result of SiTime’s
MEMS First and EpiSeal manufacturing processes is the
capability to integrate SiTime’s MEMS die with a SOC, ASIC,
microprocessor or analog die within a package to eliminate
external timing components and provide a highly integrated,
smaller, cheaper solution to the customer.
Output Voltage
The SiT1552 has two output voltage options. One option is a
standard LVCMOS output swing. The second option is the
NanoDrive reduced swing output. Output swing is customer
specific and Factory programmed between 200 mV and 800
mV. For DC-coupled applications, output V
OH
and V
OL
are
individually factory programmed to the customers’
requirement. V
OH
programming range is between 600 mV and
1.225V in 100 mV increments. Similarly, V
OL
programming
range is between 350 mV and 800 mV. For example; a PMIC
or MCU is internally 1.8V logic compatible, and requires a
1.2V V
IH
and a 0.6V V
IL
. Simply select SiT1552 NanoDrive
factory programming code to be “D14” and the correct output
thresholds will match the downstream PMIC or MCU input
requirements. Interface logic will vary by manufacturer and we
recommend that you review the input voltage requirements for
the input interface.
For DC-biased NanoDrive output configuration, the minimum
V
OL
is limited to 350mV and the maximum allowable swing
(V
OH
- V
OL
) is 750mV. For example, 1.1V V
OH
and 400mV V
OL
is acceptable, but 1.2V V
OH
and 400 mV V
OL
is not
acceptable.
When the output is interfacing to an XTAL input that is inter-
nally AC-coupled, the SiT1552 output can be Factory
programmed to match the input swing requirements. For
example, if a PMIC or MCU input is internally AC-coupled and
requires an 800mV swing, then simply choose the SiT1552
NanoDrive programming code “AA8” in the part number. It is
important to note that the SiT1552 does not include internal
AC-coupling capacitors. Please see the
Part Number
Ordering
section at the end of the datasheet for more infor-
mation about the part number ordering scheme.
TCXO Frequency Stability
The SiT1552 is factory calibrated (trimmed) over multiple
temperature points to guarantee extremely tight stability over
temperature. Unlike quartz crystals that have a classic tuning
fork parabola temperature curve with a 25°C turnover point
with a 0.04 ppm/C
2
temperature coefficient, the SiT1552
temperature coefficient is calibrated and corrected over
temperature with an active temperature correction circuit. The
result is 32 kHz TCXO with extremely tight frequency variation
over the -40°C to +85°C temperature range. Contact SiTime
for applications that require a wider supply voltage range
>3.63V, or lower operating frequency below 32 kHz.
When measuring the SiT1552 output frequency with a
frequency counter, it is important to make sure the counter's
gate time is >100 ms. The slow frequency of a 32kHz clock
will give false readings with faster gate times.
Power Supply Noise Immunity
In addition to eliminating external output load capacitors
common with standard XTALs, this device includes special
power supply filtering and thus, eliminates the need for an
external Vdd bypass-decoupling capacitor to keep the
footprint as small as possible. Internal power supply filtering
is designed to reject more than ±150 mV noise and frequency
components from low frequency to more than 10 MHz.
Rev. 1.2
Page 4 of 12
www.sitime.com
SiT1552
Smallest (1.2mm
2
), Ultra-Low Power, 32.768 kHz MEMS TCXO
The Smart Timing Choice
The Smart Timing Choice
SiT1552 NanoDrive™
Figure 2 shows a typical output waveform of the SiT1552 (into
a 10 pF load) when factory programmed for a 0.70V swing and
DC bias (V
OH
/V
OL
) for 1.8V logic:
Example:
• NanoDrive part number coding: D14. Example part
number: SiT1552AI-JE-D14-32.768
• V
OH
= 1.1V, V
OL
= 0.4V (V_
sw
= 0.70V)
these applications, refer to Table 2 for the acceptable voltage
swing options.
Table 2. Acceptable NanoDrive Voltage Swing Options
(for downstream AC-coupled receivers)
Swing
Output
Code
0.800
AA8
0.700
AA7
0.600
AA6
0.500
AA5
0.400
AA4
0.300
AA3
0.250
AA2
0.200
AA1
Example:
• NanoDrive part number coding: AA2. Example part number:
SiT1552AI-JE-AA2-32.768
• Output voltage swing: 0.250V
The values listed in Tables 1 and -2 are nominal values at 25°C
and will exhibit a tolerance of ±55 mV across Vdd and -40°C
to 85°C operating temperature range.
V
OH
= 1.1V
V
SW
= 0.7V
SiT1552 Full Swing LVCMOS Output
V
OL
= 0.4V
Figure 2. SiT1552AI-JE-D14-32.768
Output Waveform (10 pF Load)
Table 1 shows the supported NanoDrive V
OH
, V
OL
factory
programming options.
Table 1. Acceptable V
OH
/V
OL
NanoDrive Levels
V
OL
/V
OH
0.800
0.700
0.525
0.500
0.400
0.350
1.225
D28
D27
D26
D25
1.100
D18
D17
D16
D15
D14
D13
1.000
D08
D07
D06
D05
D04
D03
D97
D96
D95
D94
D93
D86
D85
D84
D83
D75
D74
D73
D64
D63
0.900
0.800
0.700
0.600
Figure 3. LVCMOS Waveform
(Vdd = 1.8V) into 15 pF Load
Example:
• LVCMOS output part number coding is always
DCC
• Example part number: SiT1552AI-JE-DCC-32.768
Table 2 shows the supported AC coupled Swing levels. The
“AC-coupled” terminology refers to the programming
description for applications where the downstream chipsets
includes an internal AC-coupling capacitor, and therefore, only
据外媒报道，萨里大学（University of Surrey）的研究人员开发出一种无需依赖GPS即可在人口密集的城市地区精确定位设备位置的人工智能系统。该系统可将定位误差从734米缩小到22米以内，这对于自动驾驶汽车和救援车辆等技术的发展意义重大。 图片来源： 萨里大学 在发表于《IEEE Robotics and Automation Letters》的论文中，研究人员介绍了PEn...[详细]
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