32KHZ.PDF

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DS32KHz
32.768 KHz TCXO
www.dalsemi.com
FEATURES
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§
§
§
§
§
Accurate to
±4
Min/Yr. (-40°C to +85°C)
Accurate to
±1
Min/Yr. (0°C to 40°C)
Battery back up for continuous time keeping
V
BAT
operating voltage 2.7 to 5.5 volts with
V
CC
grounded
V
CC
operating voltage 4.5 to 5.5 volts
Operating temperature range:
COM: 0°C to 70°C
IND: -40°C to +85°C
No calibration required
Low power consumption
Surface mountable using BGA package
V
CC
:
V
BAT
:
32KHz:
GND:
C2, C3, D2, D3
A4, A5, B4, B5
C4, C5, D4, D5
All Remaining Balls
PIN ASSIGNMENT
A
1
2
3
4
5
6
7
8
9
B
C
D
§
§
§
DS32KHz 36-Pin SMD
(TOP VIEW)
NC
1
2
3
GND
V
BAT
NC
NC
4
5
6
7
14
13
12
11
10
9
8
NC
V
CC
32 KHz OUT
GND
GND
NC
NC
ORDERING INFORMATION
Part Number
DS32KHZ/BGA
DS32KHZN/BGA
DS32KHZ/DIP
DS32KHZN/DIP
Package
36-pin BGA
36-pin BGA
14-pin DIP
14-pin DIP
Temp. Range
Commercial
Industrial
Commercial
Industrial
DS32KHz
14-PIN DIP MODULE
(300 MIL)
DESCRIPTION
The DS32KHz is a temperature compensated crystal oscillator (TCXO) with an output frequency of
32.768 kHz. This device addresses applications requiring better timekeeping accuracy and may be used to
drive the X1 input of most Dallas Semiconductor Real Time Clocks (RTC’s), chipsets and other IC’s
containing RTC’s. This device is available in commercial and industrial temperature versions, DS32KHz
and DS32KHz–N respectively.
The DS32KHz requires four pins for operation: V
CC
, GND, V
BAT
and 32KHz OUT. See Figures 1, 2 and
3 for connection schemes. Power is applied via V
CC
and GND, while V
BAT
is used to maintain the 32KHz
output in the absence of power. The output is accurate to
±7.5
ppm (±4 min/yr) from –40°C to +85°C and
±2
ppm (±1 min/yr) from 0°C to 40°C.
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DS32kHz
The DS32KHz is packaged in a small 36–pin SMD, utilizing Ball Grid Array (BGA) technology, with
dimensions 0.400 inches wide, 0.450 inches long, and 0.180 inches high. Also availabe in a 14–pin DIP
module.
The additional board space required is negligible in most applications and therefore the recommended
land pattern layout should be implemented on all new designs and future board revisions to satisfy
applications requiring better timekeeping accuracy
.
DELTA TIME vs TEMPERATURE
DELTA FREQUENCY vs TEMPERATURE
DELTA FREQUENCY (PPM)
DELTA TIME (MIN/YR)
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DS32kHz
POWER SUPPLY CONNECTIONS
Figure 1.0
Figure 2.0
Figure 1.0 shows how the DS32KHz should be connected when using two power supplies. V
CC
should be
between 4.5 and 5.5 volts while V should be between 2.7 and 3.3 volts. Figure 2.0 shows how the
BAT
DS32KHz can be used when only a single supply system is available. V
CC
should be grounded and V
BAT
should then be held between 2.7 and 5.5 volts. The V
BAT
pin should be connected directly to a battery
using no external components.
DS32KHz CONNECTIONS
Figure 3.0
Figure 4.0
Figure 3.0 illustrates how a standard 32.768 kHz crystal and the DS32KHz should be connected to
address the interchangeable option. Using this connection scheme and the recommended layout provides
a solution which requires no hardware modifications. Only one device should be used at a time and both
layouts should be located very close together if the recommended layout is not used.
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Oscillators in general are designed using various topologies and most are intended to be used with either a
quartz crystal or resonator. With this in mind, some oscillators may consume more power when driven by
another oscillator instead of a quartz crystal or resonator. There are various circuits that can be used to
reduce this increased power. Figure 4.0 shows one recommended circuit that can be used to reduce the
total current consumption of a DS32KHz and an RTC. The value of resistance, R, will vary depending on
the RTC used. However, a value of 1.0 MΩ is recommended as a starting point.
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
∗
-3.0V to +7.0V
0°C to 70°C - Commercial
-40°C to +85°C - Industrial
-40°C to +85°C
+260°C for 10 seconds (2 times max.)
This is a stress rating only and functional operation of the device at these or any other conditions
above those indicated in the operation sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods of time may affect reliability.
The Dallas Semiconductor DS32KHz is built to the highest quality standards and manufactured for long
term reliability. All Dallas Semiconductor devices are made using the same quality materials and
manufacturing methods. However, the DS32KHz is not exposed to environmental stresses, such as burn-
in, that some industrial applications require. For specific reliability information on this product, please
contact the factory in Dallas at (972) 371-4448.
RECOMMENDED DC OPERATING CONDITIONS
PARAMETER
Power Supply Voltage
Battery Voltage
SYMBOL
V
CC
V
BAT
MIN
4.5
2.7
TYP
5.0
3.0
MAX
5.5
3.3, 5.5
(-40°C to +85°C)
UNITS
V
V
NOTES
1
1, 7
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Active Supply Current
Active Battery Current
(V
CC
=0V, V
BAT
=3.3V)
High Output Voltage
I
OH
=-1.0 mA)
Low Output Voltage
(I
OL
=2.1 mA)
Battery Switch Voltage
SYMBOL
I
CC
I
BAT
V
OH
V
OL
V
SW
MIN
(V
CC
=4.5V to 5.5V; -40°C to +85°C)
TYP
150
1
MAX
180
4
UNITS
µA
µA
V
0.4
V
BAT
V
V
NOTES
2, 8
3, 8
6
6
2.4
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DS32kHz
AC TIMING CHARACTERISTICS
PARAMETER
Output Frequency
Frequency Stability vs Temp
(0°C to 40°C)
(-40°C to +85°C)
Duty Cycle
Cycle Time
High/Low Time
Rise Time
Fall Time
Oscillator Start-Up Time
Frequency Stability vs
Operating Voltage
SYMBOL
f
OUT
∆f/f
O
T
W
/T
t
CYC
t
H
/t
L
t
R
t
F
t
OSC
∆f/
V
45
MIN
(V
CC
=4.5V to 5.5V; -40°C to +85°C)
TYP
32.768
±2.0
±7.5
50
30.518
15.06
200
60
150
±1.0
MAX
±7.5
55
UNITS
kHz
PPM
%
µs
µs
ns
ns
ms
PPM/
V
NOTES
4
4
4
4
4
NOTES:
1. All voltages are referenced to ground.
2. Typical values are at +25°C and nominal supplies.
3. This current is the active mode current sourced from the backup supply/battery.
4. These parameters are measured using a 15 pF load.
5. DS32KHz-N is tested over the industrial temperature range to meet the specifications above.
6. These parameters are measured with V
CC
on under nominal operating conditions.
7. When V
CC
is grounded V
BAT
can operate from 2.7V to 5.5V. Freq. stability will be affected in this
operation, typically 1PPM/Volt above or below 3.0V.
8. These parameters are measured under no load conditions. The difference between I
CC
and I
BAT
is due
to power switching circuitry.
9. Typical crystal aging is
±1
ppm/yr after reflow.
32KHz OUTPUT WAVEFORM
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