Rev 2; 4/08
10MHz to 51.84MHz TCXO
General Description
The DS4026 is a temperature-compensated crystal
oscillator (TCXO) that provides ±1ppm frequency stabili-
ty over the -40°C to +85°C industrial temperature range.
The DS4026 is also available in Stratum 3 versions (see
the
Ordering Information—Stratum 3
table). Each device
is factory calibrated over temperature to achieve the
±1ppm frequency stability. Standard frequencies for the
device include 10, 12.8, 19.44, 20, 38.88, 40, and
51.84MHz. Contact the factory for custom frequencies.
The DS4026 provides excellent phase-noise characteris-
tics. The output is a push-pull CMOS square wave with
symmetrical rise and fall times. In addition, the DS4026
is designed to provide a maximum frequency deviation
of less than ±4.6ppm over 20 years. The device also
provides an I
2
C interface to allow pushing and pulling
of the output frequency by a minimum of ±8ppm
(±5ppm for 10MHz) with typical 1ppb resolution.
The DS4026 implements a temperature-to-voltage con-
version with a nonlinear relationship. The output from
the temperature-to-voltage converter is used to drive
the voltage-controlled crystal oscillator to compensate
for frequency change.
The device implements an on-chip temperature sensor
lookup table, and a digital-to-analog converter (DAC) to
adjust the frequency. An I
2
C interface used to commu-
nicate with the DS4026 performs temperature readings
and frequency push-pull.
Features
♦
±1ppm Frequency Accuracy Over -40°C to +85°C
♦
Standard Frequencies: 10, 12.8, 19.44, 20, 38.88,
40, 51.84MHz
♦
Stratum 3 Frequencies: 10, 12.8, 19.2, 20MHz
♦
Maximum ±4.6ppm Deviation Over 20 Years
♦
Minimum ±8ppm (±5ppm for 10MHz) Digital
Frequency Tuning Through I
2
C Interface
♦
Surface-Mount 16-Pin SO Package
♦
Pb Free/RoHS Compliant
DS4026
Pin Configuration
TOP VIEW
+
GNDA 1
V
REF
2
V
CC
3
V
OSC
4
GNDOSC 5
N.C. 6
N.C. 7
N.C. 8
16 V
CCD
15 FOUT
14 GNDD
13 SCL
DS4026
12 SDA
11 GND
10 N.C.
9
N.C.
Applications
Reference Clock Generation
Telecom/Datacom/SATCOM
Wireless
Test and Measurement
Ordering Information
PART
DS4026S+ACC
DS4026S+ACN
DS4026S+BCC
DS4026S+BCN
DS4026S+ECC
DS4026S+ECN
DS4026S+FCC
DS4026S+FCN
TEMP RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
OUTPUT (f
C
)
(MHz, CMOS)
10.00
10.00
12.80
12.80
16.80
16.80
16.384
16.384
PIN-PACKAGE
16 SO
16 SO
16 SO
16 SO
16 SO
16 SO
16 SO
16 SO
TOP MARK*
DS4026-ACC
DS4026-ACN
DS4026-BCC
DS4026-BCN
DS4026-ECC
DS4026-ECN
DS4026-FCC
DS4026-FCN
Ordering Information continued at end of data sheet.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*The top mark will include a “+” for a lead(Pb)-free/RoHS-compliant device.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
10MHz to 51.84MHz TCXO
DS4026
ABSOLUTE MAXIMUM RATINGS
Voltage Range on V
CC
, V
CCD
, and V
OSC
Relative to Ground..............................................-0.3V to +3.8V
Voltage Range on SDA, SCL, and FOUT
Relative to Ground...................................-0.3V to (V
CC
+ 0.3V)
Operating Temperature Range (noncondensing)....-40°C to +85°C
Storage Temperature Range ...............................-40°C to +85°C
Soldering Temperature...........................Refer to the IPC/JEDEC
J-STD-020 Specification.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
Power-Supply Voltage
Oscillator Power Supply
Driver Power Supply
SYMBOL
V
CC
V
OSC
V
CCD
CONDITIONS
MIN
3.135
3.135
3.135
TYP
3.3
3.3
3.3
MAX
3.465
3.465
3.465
UNITS
V
V
V
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 3.135V to 3.465V, T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 1, 2, 3)
PARAMETER
V
CC
Active-Supply Current
V
OSC
Oscillator Active-Supply
Current
SYMBOL
I
CC
(Note 4)
FOUT CMOS output on, CL = 10pF,
frequency < 25MHz
FOUT CMOS output on, CL = 10pF,
frequency 25MHz
FOUT CMOS output on, CL = 10pF,
frequency < 25MHz
I
CCD
FOUT CMOS output on, CL = 10pF,
frequency 25MHz
-1
Output off
-1
0.7 x
V
CC
-0.3
V
CC
= 3.0V, V
OL
= 0.4V
V
CCD
= 3V, I
OH
= -2mA
V
CCD
= 3V, I
OL
= 2.0mA
(0.1 x V
CCD
) - (0.9 x V
CCD
)
0.5 x V
CCD
(Note 5)
2.4
0.4
2
45
55
CONDITIONS
MIN
TYP
1.5
3
5
2
3
MAX
2.5
4
mA
9
3
mA
5
+1
+1
V
CC
+ 0.3
+0.3 x
V
CC
3
μA
μA
V
V
mA
V
V
ns
%
UNITS
mA
I
OSC
V
CCD
Driver Active-Supply
Current
SCL Input Leakage
SDA Leakage
SCL, SDA High Input Voltage
SCL, SDA Low Input Voltage
SDA Logic 0 Output
FOUT High Output Voltage
FOUT Low Output Voltage
FOUT Rise/Fall Time
FOUT Duty Cycle
I
LI
I
LO
V
IH
V
IL
I
OL
V
OH
V
OL
t
R
/t
F
t
D
2
_______________________________________________________________________________________
10MHz to 51.84MHz TCXO
AC ELECTRICAL CHARACTERISTICS—TCXO
(V
CC
= 3.135V to 3.465V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER
Frequency Stability vs.
Temperature
Frequency Stability vs. Voltage
Aging
Frequency Pull
Range
First Year
Years 2–20
Except 10MHz
10MHz
SYMBOL
f/f
C
CONDITIONS
CL = 10pF to ground
MIN
f
C
– 1ppm
-2
-1
-2
±8
±5
±15
±10
1
TYP
f
C
MAX
f
C
+ 1ppm
+2
+1
+2
UNITS
ppm
ppm/V
ppm
ppm
ppb
DS4026
f
VOLTAGE
CL = 10pF to ground, +25°C
/f
C
f
AGING
/f
C
(Note 5)
f/f
C
f
RES
/f
C
FTUNEH = 3Fh and FTUNEL = FFh;
FTUNEH = 40h and FTUNEL = 00h at +25°C
Frequency Pull Resolution
AC ELECTRICAL CHARACTERISTICS—STRATUM 3
(V
CC
= +3.135V to +3.465V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER
Frequency Stability vs.
Temperature
Initial Tolerance and Reflow
Frequency Stability vs. Voltage
Frequency Stability vs.
Aging/20 Years
Frequency Stability vs. Load
Change
Free-Run Accuracy
Holdover Stability (24 Hours)
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STRATUM 3 FREQUENCY STABILITY
f
TEMP
/f
C
-40°C to +85°C (Note 6)
-0.28
-0.8
-0.33
-3.0
-0.1
-4.6
-0.32
+0.28
+0.8
+0.33
+3.0
+0.1
+4.6
+0.32
ppm
ppm
ppm
ppm
ppm
ppm
ppm
f
INITIAL
/f
C
T
A
= +25°C, ±3°C and V
DD
= 3.3V
f
VOLTAGE
V
CC
= 3.3V ±5%, C
L
= 10pF to ground,
/f
C
+25°C (Note 7)
f
AGING
/f
C
f
C
= Nominal (Note 8)
f
LOAD
/f
C
Load = 10pF ±5%, +25°C (Note 5)
Operating temperature, load, supply, and
initial tolerance, aging (20 years) (Notes 5, 8)
f
24HOURS
24-hour elapsed time (Notes 5, 9)
/f
C
PHASE NOISE
PHASE NOISE (dBc/Hz) (TYPICAL, +25°C, 3.3V)
OFFSET (MHz)
12.80
19.44
20.00
38.88
40.00
51.84
10.0
16.384
16.8
24.0
10Hz
-88.41
-82.63
-83.71
-79.01
-80.80
-74.09
-92.52
-87.44
-89.6
-83.98
100Hz
-130.16
-125.12
-120.76
-120.06
-115.44
-120.39
-134.83
-128.53
-126.20
-119.45
1kHz
-147.84
-145.03
-145.44
-141.75
-141.17
-142.33
-147.22
-147.67
-146.88
-143.08
10kHz
-150.84
-146.87
-150.96
-150.59
-151.59
-151.14
-150.84
-150.78
-151.90
-150.33
100kHz
-151.71
-151.69
-151.18
-152.50
-152.37
-153.21
-151.25
-152.72
-152.28
-150.34
1MHz
-151.87
-151.52
-151.45
-153.06
-153.00
-153.94
-150.84
-151.75
-151.93
-150.67
CARRIER
FREQUENCY
_______________________________________________________________________________________
3
10MHz to 51.84MHz TCXO
DS4026
TEMPERATURE SENSOR ELECTRICAL CHARACTERISTICS
(V
CC
= 3.135V to 3.465V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER
Temperature Sensor Accuracy
Temperature Sensor Conversion
Time
Temperature Sensor Resolution
SYMBOL
T
t
CONVT
N2
CONDITIONS
MIN
-3
TYP
MAX
+3
11
12
UNITS
°C
ms
Bits
AC ELECTRICAL CHARACTERISTICS—I
2
C SERIAL INTERFACE
(V
CC
= 3.135V to 3.465V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
SCL Clock Frequency
Bus Free Time Between STOP
and START Conditions
Hold Time (Repeated) START
Condition (Note 10)
Low Period of SCL Clock
High Period of SCL Clock
Data Hold Time
(Notes 11, 12)
Data Setup Time (Note 13)
START Setup Time
Rise Time of Both SDA and SCL
Signals (Note 14)
Fall Time of Both SDA and SCL
Signals (Note 14)
Setup Time for STOP Condition
Pin Capacitance SDA, SCL
(Note 5)
SYMBOL
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
HD:DAT
t
SU:DAT
t
SU:STA
t
R
t
F
t
SU:STO
C
I/O
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
CONDITIONS
Standard mode
MIN
0
100
4.7
1.3
4.0
0.6
4.7
1.3
4.0
0.6
0
0
250
100
4.7
0.6
20 + 0.1C
B
20 + 0.1C
B
20 + 0.1C
B
20 + 0.1C
B
4.7
0.6
10
1000
300
300
300
0.9
0.9
TYP
MAX
100
400
UNITS
kHz
μs
μs
μs
μs
μs
ns
μs
ns
ns
μs
pF
4
_______________________________________________________________________________________
10MHz to 51.84MHz TCXO
AC ELECTRICAL CHARACTERISTICS—I
2
C SERIAL INTERFACE (continued)
(V
CC
= 3.135V to 3.465V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
Capacitive Load for Each Bus
Line (Note 14)
Pulse Width of Spikes That Must
Be Suppressed by the Input
Filter
SYMBOL
C
B
CONDITIONS
MIN
TYP
MAX
400
UNITS
pF
DS4026
t
SP
Fast mode
30
ns
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
Typical values are at +25°C, nominal supply voltages, unless otherwise indicated.
Voltages referenced to ground.
Limits at -40°C are guaranteed by design and not production tested.
Specified with I
2
C bus inactive.
Guaranteed by design and not production tested.
Frequency stability vs. temperature is defined as (Δf
MAX
-
Δf
MIN
)/2.
Maximum power-supply variations to meet the specification are 5%.
Crystal vendor specification.
Holdover is defined as (f
MAX
- f
MIN
)/2 as measured within a 24-hour period. Warmup time = 1 hour.
After this period, the first clock pulse is generated.
A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the V
IH(MIN)
of the SCL signal)
to bridge the undefined region of the falling edge of SCL.
Note 12:
The maximum t
HD:DAT
need only be met if the device does not stretch the low period (t
LOW
) of the SCL signal.
Note 13:
A fast-mode device can be used in a standard-mode system, but the requirement that t
SU:DAT
≥
250ns must then be met.
This is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does not
stretch the low period of the SCL signal, it must output the next data bit to the SDA line t
R(MAX)
+ t
SU:DAT
= 1000 + 250 =
1250ns before the SCL line is released.
Note 14:
C
B
—total capacitance of one bus line in pF.
Data Transfer on I
2
C Serial Bus
SDA
t
BUF
t
LOW
t
R
t
F
t
HD:STA
t
SP
SCL
t
HD:STA
STOP
START
t
HD:DAT
t
HIGH
t
SU:DAT
REPEATED
START
t
SU:STA
t
SU:STO
_______________________________________________________________________________________
5
