MAXIM DS4026 User Manual

General Description

The DS4026 is a temperature-compensated crystal
oscillator (TCXO) that provides ±1ppm frequency stabili­ty 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 characteris­tics. 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 I2C 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 con­version 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 commu­nicate with the DS4026 performs temperature readings
and frequency push-pull.

Applications

Reference Clock Generation Wireless

Telecom/Datacom/SATCOM Test and Measurement

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

10MHz to 51.84MHz TCXO

Pin Configuration

Rev 2; 4/08

________________________________________________________________

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.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

*The top mark will include a “+” for a lead(Pb)-free/RoHS-compliant device.

Ordering Information continued at end of data sheet.

Ordering Information

TOP VIEW

V

V

OSC

N.C.

N.C.

N.C.

REF

+

1

2

3

CC

4

DS4026

5

6

7

8

16

V

CCD

FOUT

15

GNDD

14

SCL

13

SDA

12

GND

11

N.C.

10

N.C.

9

GNDA

V

GNDOSC

PART TEMP RANGE

DS4026S+ACC

DS4026S+ACN

DS4026S+BCC

DS4026S+BCN -40°C to +85°C 12.80 16 SO DS4026-BCN

DS4026S+ECC 0°C to +70°C 16.80 16 SO DS4026-ECC

DS4026S+ECN -40°C to +85°C 16.80 16 SO DS4026-ECN

DS4026S+FCC 0°C to +70°C 16.384 16 SO DS4026-FCC

DS4026S+FCN -40°C to +85°C 16.384 16 SO DS4026-FCN

0°C to +70°C 10.00 16 SO DS4026-ACC

-40°C to +85°C 10.00 16 SO DS4026-ACN

0°C to +70°C 12.80 16 SO DS4026-BCC

OUTPUT (f

(MHz, CMOS)

)

C

PIN-PACKAGE TOP MARK*

DS4026

10MHz to 51.84MHz TCXO

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED DC OPERATING CONDITIONS

(TA= -40°C to +85°C, unless otherwise noted.)

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.

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.

DC ELECTRICAL CHARACTERISTICS

(VCC= 3.135V to 3.465V, TA= -40°C to +85°C, unless otherwise noted.) (Notes 1, 2, 3)

Power-Supply Voltage VCC 3.135 3.3 3.465 V

Oscillator Power Supply V

Driver Power Supply V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

OSC

CCD

VCC Active-Supply Current ICC (Note 4) 1.5 2.5 mA

V

OSC

Current

V

CCD

Current

SCL Input Lea kage ILI -1 +1 μA

SDA Leakage ILO Output off -1 +1 μA

SCL, SDA High Input Voltage V

SCL, SDA Low Input Voltage VIL -0.3

SDA Logic 0 Output IOL VCC = 3.0V, VOL = 0.4V 3 mA

FOUT High Output Voltage VOH V

FOUT Low Output Voltage VOL V

FOUT Rise/Fall Time tR/tF (0.1 x V

FOUT Duty C yc le tD 0.5 x V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

FOUT CMOS output on, CL = 10pF,

Oscillator Active-Supply

Driver Active-Supply

I

OSC

I

CCD

frequency < 25MHz

FOUT CMOS output on, CL = 10pF,
frequency  25MH z

FOUT CMOS output on, CL = 10pF,
frequency < 25MHz

FOUT CMOS output on, CL = 10pF,
frequency  25MH z

IH

= 3V, IOH = -2mA 2.4 V

CCD

= 3V, IOL = 2.0mA 0.4 V

CCD

CCD

CCD

3.135 3.3 3.465 V

3.135 3.3 3.465 V

0.7 x
V

CC

) - (0.9 x V

(Note 5) 45 55 %

) 2 ns

CCD

3 4

5 9

2 3

3 5

V

CC

+ 0.3

+0.3 x

V

CC

mA

mA

V

V

DS4026

10MHz to 51.84MHz TCXO

_______________________________________________________________________________________ 3

AC ELECTRICAL CHARACTERISTICS—TCXO

(VCC= 3.135V to 3.465V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

AC ELECTRICAL CHARACTERISTICS—STRATUM 3

(VCC= +3.135V to +3.465V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

PHASE NOISE

Frequency Stability vs.
Temperature

Frequency Stability vs. Voltage

Aging

Frequency Pull
Range

Frequency Pull Re so lution f

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

f/f

CL = 10pF to ground

C

f

VOLTAGE

/f

First Year -1 +1

Years 2–20

Except 10MHz ±8 ±15

10MHz

f

AGING/fC

f/f

RES/fC

CL = 10pF to ground, +25°C -2 +2 ppm/V

C

(Note 5)

FTUNEH = 3Fh and FTUNEL = FFh;

C

FTUNEH = 40h and FTUNEL = 00h at +25°C

1 ppb

STRATUM 3 FREQUENCY STABILITY

Frequency Stability vs.
Temperature

Initial Tolerance and Reflow f

Frequency Stability vs. Voltage

Frequency Stability vs.
Aging/20 Years

Frequency Stability vs. Load
Change

Free-Run Accuracy

Holdover Stability (24 Hours)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

f

INITIAL

f

VOLTAGE

f

AGING/fC fC

f

f

24HOURS

-40°C to +85°C (Note 6) -0.28 +0.28 ppm

TEMP/fC

/fC TA = +25°C, ±3°C and VDD = 3.3V -0.8 +0.8 ppm

VCC = 3.3V ±5%, CL = 10pF to ground,

/f

LOAD/fC

/f

+25°C (Note 7)

C

= Nominal (Note 8) -3.0 +3.0 ppm

Load = 10pF ±5%, +25°C (Note 5) -0.1 +0.1 ppm

Operating temperature, load, supply, and
initial tolerance, aging (20 years) (Notes 5, 8)

24-hour elapsed time (Notes 5, 9) -0.32 +0.32 ppm

C

f

C

– 1ppm

-2 +2

±5 ±10

-0.33 +0.33 ppm

-4.6 +4.6 ppm

f

C

f

C

+ 1ppm

ppm

ppm

ppm

CARRIER

FREQUENCY

PHASE NOISE (dBc/Hz) (TYPICAL, +25°C, 3.3V)

OFFSET (MHz) 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz

12.80 -88.41 -130.16 -147.84 -150.84 -151.71 -151.87

19.44 -82.63 -125.12 -145.03 -146.87 -151.69 -151.52

20.00 -83.71 -120.76 -145.44 -150.96 -151.18 -151.45

38.88 -79.01 -120.06 -141.75 -150.59 -152.50 -153.06

40.00 -80.80 -115.44 -141.17 -151.59 -152.37 -153.00

51.84 -74.09 -120.39 -142.33 -151.14 -153.21 -153.94

10.0 -92.52 -134.83 -147.22 -150.84 -151.25 -150.84

16.384 -87.44 -128.53 -147.67 -150.78 -152.72 -151.75

16.8 -89.6 -126.20 -146.88 -151.90 -152.28 -151.93

24.0 -83.98 -119.45 -143.08 -150.33 -150.34 -150.67

AC ELECTRICAL CHARACTERISTICS—I2C SERIAL INTERFACE

(VCC= 3.135V to 3.465V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)

DS4026

10MHz to 51.84MHz TCXO

4 _______________________________________________________________________________________

TEMPERATURE SENSOR ELECTRICAL CHARACTERISTICS

(VCC= 3.135V to 3.465V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Temperature Sensor Accuracy T -3 +3 °C

Temperature Sensor Conversion
Time

Temperature Sensor Resolution N2 12 Bits

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SCL Clock Frequenc y f

Bus Free Time Between STOP
and START Condition s

Hold Time (Repeated) START
Condition (Note 10)

Low Period of SCL Clock t

High Period of SCL Clock t

Data Hold Time
(Notes 11, 12)

Data Setup Time (Note 13) t

START Setup Time t

Rise Time of Both SDA and SCL
Signals (Note 14)

Fal l Time of Both SDA and SCL
Signals (Note 14)

Setup Time for STOP Condition t

Pin Capacitance SDA, SCL
(Note 5)

t

11 ms

CONVT

SCL

t

BUF

t

HD: STA

LOW

HIGH

t

HD:DAT

SU:DAT

SU:STA

t

t

SU:STO

C

I/O

Standard mode 0 100

Fast mode 100 400

Standard mode 4.7

Fast mode 1.3

Standard mode 4.0

Fast mode 0.6

Standard mode 4.7

Fast mode 1.3

Standard mode 4.0

Fast mode 0.6

Standard mode 0 0.9

Fast mode 0 0.9

Standard mode 250

Fast mode 100

Standard mode 4.7

Fast mode 0.6

Standard mode 20 + 0.1CB 1000

R

Fast mode 20 + 0.1CB 300

Standard mode 20 + 0.1CB 300

F

Fast mode 20 + 0.1CB 300

Standard mode 4.7

Fast mode 0.6

10 pF

kHz

μs

μs

μs

μs

μs

ns

μs

ns

ns

μs

DS4026

Note 1: Typical values are at +25°C, nominal supply voltages, unless otherwise indicated.
Note 2: Voltages referenced to ground.
Note 3: Limits at -40°C are guaranteed by design and not production tested.
Note 4: Specified with I

2

C bus inactive.

Note 5: Guaranteed by design and not production tested.
Note 6: Frequency stability vs. temperature is defined as (Δf

MAX

- Δf

MIN

)/2.

Note 7: Maximum power-supply variations to meet the specification are 5%.
Note 8: Crystal vendor specification.
Note 9: Holdover is defined as (f

MAX

- f

MIN

)/2 as measured within a 24-hour period. Warmup time = 1 hour.

Note 10: After this period, the first clock pulse is generated.
Note 11: 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.

AC ELECTRICAL CHARACTERISTICS—I2C SERIAL INTERFACE (continued)

(VCC= 3.135V to 3.465V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)

10MHz to 51.84MHz TCXO

_______________________________________________________________________________________ 5

Data Transfer on I2C Serial Bus

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Capacitive Load for Each Bus
Line (Note 14)

Pulse Width of Spikes That Must
Be Suppressed by the Input
Filter

400 pF

C

B

t

Fast mode 30 ns

SP

SDA

SCL

t

BUF

STOP START

t

t

t

SU:STA

HD:STA

t

LOW

t

HD:STA

t

R

t

HD:DAT

t

F

t

HIGH

t

SU:DAT

REPEATED

START

SP

t

SU:STO