SiT1533
20 ppm, Ultra-Low Power 32.768 kHz Quartz XTAL Replacement
Smallest (1.2mm
2
), Ultra-Low Power, 32.768 kHz MEMS TCXO
Features
Applications
Small SMD package:
2.0 x 1.2 mm (2012)
[1]
Pin-compatible to 2012 XTAL SMD package
Fixed 32.768 kHz output frequency
<20 ppm frequency tolerance Ultra-low power: <1 µA
Supports coin-cell or super-cap battery backup voltages
Vdd supply range:
1.5V to 3.63V over -40°C to +85°C
Oscillator output eliminates external load caps
Internal filtering eliminates external Vdd bypass cap
NanoDrive™ programmable output swing for lowest power
Pb-free, RoHS and REACH compliant
Mobile Phones
Tablets
Health and Wellness Monitors
Fitness Watches
Sport Video Cams
Wireless Keypads
Ultra-Small Notebook PC
Pulse-per-Second (pps) Timekeeping
RTC Reference Clock
Battery Management Timekeeping
Note:
1. For the smallest 32 kHz XO in CSP (1.2 mm
2
), consider the
SiT1532.
Electrical Specifications
Table 1. Electrical Characteristics
Parameter
Fixed Output Frequency
Frequency Tolerance
Frequency Stability
25°C Aging
[3]
[2]
Symbol
Fout
F_tol
F_stab
Min.
Typ.
32.768
Max.
Unit
kHz
Condition
Frequency and Stability
Frequency Stability
20
75
100
250
-1
1.2
1.5
0.90
Core Operating Current
[4]
ppm
ppm
ppm
V
V
μA
μA/Vpp
ms
ms
T
A
= 25°C, post reflow, Vdd: 1.5V – 3.63V.
T
A
= -10°C to +70°C, Vdd: 1.5V – 3.63V.
T
A
= -40°C to +85°C, Vdd: 1.5V – 3.63V.
T
A
= -10°C to +70°C, Vdd: 1.2V – 1.5V.
1
st
Year
T
A
= -10°C to +70°C
T
A
= -40°C to +85°C
T
A
= 25°C, Vdd: 1.8V. No load
T
A
= -10°C to +70°C, Vdd max: 3.63V. No load
T
A
= -40°C to +85°C, Vdd max: 3.63V. No load
T
A
= -40°C to +85°C, Vdd: 1.5V – 3.63V. No load
T
A
= -40°C to +85°C, 0 to 90% Vdd
T
A
= -40°C ≤ T
A
≤ +50°C, valid output
T
A
= +50°C < T
A
≤ +85°C, valid output
1
3.63
3.63
1.3
1.4
0.065
180
0.125
100
300
450
Operating Temperature Range
Supply Voltage and Current Consumption
Operating Supply Voltage
Vdd
Idd
[4]
Output Stage Operating Current
Power-Supply Ramp
Start-up Time at Power-up
[5]
Idd_out
t_Vdd_ Ramp
t_start
Commercial Temperature
Industrial Temperature
T_use
-10
-40
70
85
°C
°C
Notes:
2. Measured peak-to-peak. 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.
3. Stability is specified for two operating voltage ranges. Stability progressively degrades with supply voltage below 1.5V. Measured peak -to-peak.
Inclusive of Initial Tolerance at 25°C, and variations over operating temperature, rated power supply voltage and load.
4. Core operating current does not include output driver operating current or load current. To derive total operating current (no load), add core
operating current + (0.065 µA/V) * (peak-to-peak output Voltage swing).
5. Measured from the time Vdd reaches 1.5V.
Rev 1.4
March 20, 2018
www.sitime.com
SiT1533
20 ppm, Ultra-Low Power 32.768 kHz Quartz XTAL Replacement
Table 1. Electrical Characteristics (continued)
Parameter
Symbol
Min.
Typ.
100
tr, tf
DC
VOH
VOL
tf, tf
DC
48
90%
10%
Max.
200
50
52
ns
%
V
V
Vdd: 1.5V – 3.63V. I
OH
= -10 μA, 15 pF
Vdd: 1.5V – 3.63V. I
OL
= 10 μA, 15 pF
Unit
Condition
10-90% (Vdd), 15 pF load, Vdd = 1.5V to 3.63V
10-90% (Vdd), 5 pF load, Vdd ≥ 1.62V
LVCMOS Output Option, T
A
= -40°C to +85°C, typical values are at T
A
= 25°C
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
Period Jitter
NanoDrive™ Programmable, Reduced Swing Output
200
ns
30-70% (V
OL
/V
OH
), 10 pF Load
48
0.20 to
0.80
0.60 to
1.225
0.35 to
0.80
-0.055
0.055
35
52
%
SiT1533 does not internally AC-couple. This output description
is intended for a receiver that is AC-coupled. See
Table 2
for
acceptable NanoDrive swing options.
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. See
Table 1
for
acceptable V
OH
/V
OL
setting levels.
Vdd: 1.5V – 3.63V. I
OL
= 0.2 μA, 10 pF Load. See
Table 1
for
acceptable V
OH
/V
OL
setting levels.
T
A
= -40°C to +85°C, Vdd = 1.5V to 3.63V.
Cycles = 10,000, T
A
= 25°C, Vdd = 1.5V – 3.63V
V_sw
V
VOH
VOL
V
V
V
ns
RMS
T_jitt
Table 2. Pin Configuration
SMD Pin
Symbol
I/O
Functionality
No Connect. Will not respond to any input signal. When interfacing to
an MCU’s XTAL input pins, this pin is typically connected to the
receiving IC’s X Out pin. In this case, the SiT1533 will not be affected
by the signal on this pin. If not interfacing to an XTAL oscillator, leave
pin 1 floating (no connect).
Connect to ground. All GND pins must be connected to power
supply 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 SiT1533 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 for operation over
-40°C to +85°C temperature range. Under normal operating
conditions, Vdd does not require external bypass/decoupling
capacitor(s). Internal power supply filtering will reject more than
±150 mVpp with frequency components through 10 MHz.
Contact
SiTime
for applications that require a wider operating supply
voltage range.
NC
1
2
GND
SMD Package (Top View)
Vdd
4
3
CLK Out
1
NC
No Connect
2
GND
Power Supply
Ground
3
CLK Out
OUT
Figure 1. Pin Assignments
4
Vdd
Power Supply
Rev 1.4
Page 2 of 13
www.sitime.com
SiT1533
20 ppm, Ultra-Low Power 32.768 kHz Quartz XTAL Replacement
System Block Diagram
MEMS Resonator
NC
Control
Regulators
Vdd
Trim
Prog
Prog
GND
Sustaining
Amp
Ultra-Low
Power
PLL
Divider
Ultra-Low
Power Driver
CLK Out
Figure 2. SiT1533 Block Diagram
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 maximu m 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 ESD Protection
Charge-Device Model (CDM) ESD Protection
Machine Model (MM) ESD Protection
Latch-up Tolerance
Mechanical Shock Resistance
Mechanical Vibration Resistance
2012 SMD Junction Temperature
Storage Temperature
Mil 883, Method 2002
Mil 883, Method 2007
≤30 minutes, over -40°C to +85°C
Vdd = 1.5V - 3.63V
Vdd = 1.5V - 3.63V, ≤30 mins
HBM, JESD22-A114
JESD220C101
T
A
= 25°C
Test Condition
Value
-0.5 to 3.63
4.0
105
125
3000
750
300
JESD78 Compliant
10,000
70
150
-65°C to 150°C
g
g
°C
Unit
V
V
°C
°C
V
V
V
Rev 1.4
Page 3 of 13
www.sitime.com
SiT1533
20 ppm, Ultra-Low Power 32.768 kHz Quartz XTAL Replacement
Description
The SiT1533 is an ultra-small and ultra-low power 32.768 kHz
oscillator optimized for mobile and other battery-powered
applications. The SiT1533 is pin-compatible and footprint
compatible to existing 2012 XTALs when using the SiTime
solder-pad layout (SPL). And unlike standard oscillators, the
SiT1533 features NanoDrive™, a factory programmable
output that reduces the voltage swing to minimize power.
The 1.2V to 3.63V operating supply voltage range makes it an
ideal solution for mobile applications that incorporate a
low-voltage, battery-back-up source such as a coin-cell or
super-cap.
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.
Frequency Stability
The SiT1533 is factory calibrated (trimmed) to guarantee
frequency stability to be less than 20 ppm at room
temperature and less than 100 ppm over the full -40°C to
+85°C temperature range. Unlike quartz crystals that have a
classic tuning fork parabola temperature curve with a 25°C
turnover point, the SiT1533 temperature coefficient is
extremely flat across temperature. The device maintains less
than 100 ppm frequency stability over the full operating
temperature range when the operating voltage is between
1.5 and 3.63V as shown in
Figure 4.
Functionality is guaranteed over the 1.2V – 3.63V operating
supply voltage range. However, frequency stability degrades
below 1.5V and steadily degrades as it approaches the 1.2V
minimum supply due to the internal regulator limitations.
Between 1.2V and 1.5V, the frequency stability is 250 ppm
max over temperature.
When measuring the SiT1533 output frequency with a
frequency counter, it is important to make sure the counter's
gate time is >100ms. The slow frequency of a 32 kHz clock
will give false readings with faster gate times.
Contact
SiTime
for alternative 32 kHz product options and
applications that require a wider supply voltage range
>3.63V, or operating frequency below 32 kHz.
Frequency Stability (ppm)
SiT153x Industrial Temp Specification
SiT1533 20 ppm
Max @ 25C
SiT1533 Measured
XTAL Footprint Compatibility (SMD Package)
The SiT1533 is a replacement to the 32 kHz XTAL in the
2.0 x 1.2 mm (2012) package. Unlike XTAL resonators,
SiTime’s silicon MEMS oscillators require a power supply
(Vdd) and ground (GND) pin. Vdd and GND pins are
conveniently placed between the two large XTAL pins.
When using the SiTime Solder Pad Layout (SPL), the
SiT1533 footprint is compatible with existing 32 kHz XTALs
in the 2012 SMD package.
Figure 3
shows the comparison
between the quartz XTAL footprint and the SiTime footprint.
For applications that require the smallest footprint solution,
consider the SiT1532 XO available in a 1.2mm
2
CSP.
Quartz
SiTime
Connect to
X OUT or NC
1
Quartz XTAL
-160 to -220 ppm Over Temp
Temperature (°C)
Figure 4. SiTime vs. Quartz
Power Supply Noise Immunity
The SiT1533 is an ultra-small 32 kHz oscillator. 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. This feature further simplifies
the design and keeps the footprint as small as possible.
Internal power supply filtering is designed to reject AC-noise
greater than ±150 mVpp magnitude and beyond 10 MHz
frequency component.
X OUT
GND
2
4
VDD
3
X IN
Clock Out
Connect to X IN
Top View
Output Voltage
The SiT1533 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 programmed between 200 mV and
800 mV. For DC-coupled applications, output VOH and VOL
are individually factory programmed to the customers’
Top View
Figure 3. SiT1533 Footprint Compatibility with Quartz
XTAL Footprint
[6]
Note:
6. On the SiTime device, X IN is not internally connected and will not
respond to any signal. It is acceptable to connect to chipset X OUT.
Rev 1.4
Page 4 of 13
www.sitime.com
SiT1533
20 ppm, Ultra-Low Power 32.768 kHz Quartz XTAL Replacement
requirement. VOH programming range is between 600 mV
and 1.225V in 100 mV increments. Similarly, VOL
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 VIH and a 0.6V VIL.
Simply select SiT1533 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
VOL is limited to 350mV and the maximum allowable swing
(VOH - VOL) is 750mV. For example, 1.1V VOH and
400mV VOL is acceptable, but 1.2V VOH and 400 mV VOL is
not acceptable.
When the output is interfacing to an XTAL input that is
internally AC-coupled, the SiT1533 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 SiT1533
NanoDrive programming code “AA8” in the part number. It is
important to note that the SiT1533 does not include internal
AC-coupling capacitors. Please see the
Part Number
Ordering
section at the end of the datasheet for more
information about the part number ordering scheme.
Power-up
The SiT1533 starts-up to a valid output frequency within
300 ms (150ms 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). Start-up
time is measured from the time Vdd reaches 1.5V.
For applications that operate between 1.2V and 1.5V, the
start-up time will be longer.
Rev 1.4
Page 5 of 13
www.sitime.com
PCB设计
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
