PRELIMINARY
DS76KHz
76.8 kHz TCXO
www.dalsemi.com
FEATURES
Accurate to
±7.5
ppm (-40°C to +85°C)
Accurate to
±2
ppm (0°C to 40°C)
Battery back up for continuous output
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
V
CC
:
V
BAT
:
76KHz:
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
DS76KHz 36-Pin SMD
(TOP VIEW)
DESCRIPTION
The DS76KHz is a temperature-compensated crystal oscillator (TCXO) with an output frequency of 76.8
kHz. This device is available in commercial and industrial temperature versions, DS76KHz and
DS76KHz-N respectively.
The DS76KHz requires four pins for operation: V
CC
, GND, V
BAT
and 76KHz 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 76KHz
output in the absence of power. The output is accurate to
±7.5
ppm from -40°C to +85°C and
±2
ppm
from 0°C to 40°C.
The DS76KHz 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.
The recommended land pattern layout is shown on page 5.
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 accuracy.
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050599
DS76KHz
DELTA FREQUENCY vs TEMPERATURE
POWER SUPPLY CONNECTIONS
Figure 1.0
Figure 2.0
Figure 1.0 shows how the DS76KHz should be connected when using two power supplies. V
CC
should be
between 4.5 and 5.5 volts while V
BAT
should be between 2.7 and 3.3 volts. Figure 2.0 shows how the
DS76KHz can be used when only a single supply 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. Figure 2.0 illustrates how the DS76KHz can be used in a single supply system.
DS76KHz CONNECTIONS
V
CC
Figure 3.0
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DS76KHz
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 DS76KHz 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 DS76KHz 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
AC TIMING CHARACTERISTICS
PARAMETER
Output Frequency
Frequency Stability vs Temp
(0°C to 40°C)
(-40°C to +85°C)
Frequency Stability vs
Operating Voltage
Duty Cycle
Cycle Time
High/Low Time
Rise Time
Fall Time
Oscillator Start-Up Time
SYMBOL
f
OUT
∆f/f
O
∆f/
V
T
W
/T
t
CYC
t
H
/t
L
t
R
t
F
t
OSC
45
MIN
(V
CC
=4.5V to 5.5V; -40°C to +85°C)
TYP
76.8
±2.0
±7.5
±1.0
50
13.021
6.31
325
75
150
55
MAX
±7.5
UNITS
kHz
PPM
NOTES
ppm/
V
%
µs
µs
ns
ns
ms
4
4
4
4
4
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DS76KHz
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. DS76KHz-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.
76KHz OUTPUT WAVEFORM
MECHANICAL DIMENSIONS
4 of 5
DS76KHz
RECOMMENDED LAND PATTERN LAYOUT (36-Pin BGA)
5 of 5
微控制器 MCU
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