DS1090_V01 [MAXIM]
Low-Frequency, Spread-Spectrum EconOscillator;
| 型号： | DS1090_V01 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Low-Frequency, Spread-Spectrum EconOscillator |
| 文件： | 总9页 (文件大小：479K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS1090
Low-Frequency, Spread-Spectrum EconOscillator
General Description
Features
● Low-Cost, Spread-Spectrum EconOscillator™
The DS1090 is a low-cost, dithered oscillator intended
to be used as an external clock for switched-mode
power supplies and other low-frequency applications. The
dithering or sweeping function reduces peak-radiated
emissions from the power supply at its fundamental
frequency, as well as harmonic frequencies. The device
consists of a resistor-programmed master oscillator, fac-
tory-programmed clock prescaler, and a pin-programmed
dither circuit. These features allow the DS1090 to be used
in applications where a spread-spectrum clock is desired
to reduce radiated emissions. A combination of factory-set
prescalers and external resistor allows for output frequencies
ranging from 125kHz to 8MHz. Both dither frequency and
dither percentage are set using control pins.
● Simple User Programming
●
Output Frequency Programmable from 125kHz to 8MHz
● Dither Percentage Programmable from 0% to 8%
● Dither Rate Programmable (f
/512, 1024, 2048,
MOSC
or 4096)
● 3.0V to 5.5V Single-Supply Operation
● CMOS/TTL-Compatible Output
● Operating Temperature Range: -40°C to +85°C
Ordering Information
OUTPUT
PIN-
PACKAGE
PART
FREQUENCY PRESCALER
RANGE
Applications
● Switched-Mode Power Supplies
● Servers
● Printers
DS1090U-1+
DS1090U-2+
DS1090U-4+
4MHz to 8MHz
2MHz to 4MHz
1MHz to 2MHz
1
2
4
8 µSOP
8 µSOP
8 µSOP
500kHz to
1MHz
● Embedded Microcontrollers
● Industrial Controls
DS1090U-8+
DS1090U-16+
DS1090U-32+
8
8 µSOP
8 µSOP
8 µSOP
250kHz to
500kHz
16
32
125kHz to
250kHz
Typical Operating Circuit
Add “T” for Tape & Reel orders.
V
V
OUT
IN
Pin Configuration
V
V
CC
CC
DC-DC
STEP-DOWN
CONVERTER
TOP VIEW
OUT
JC0
OUT
1
2
3
4
8
7
6
5
JC1
JC0
J1
DS1090
JC1
J0
R
SET
DS1090
R
SET
V
CC
45kΩ
TO 91kΩ
J1
GND
GND
J0
µSOP
EconOscillator is a trademark of Maxim Integrated Products, Inc.
19-7500; Rev 3; 9/16
DS1090
Low-Frequency, Spread-Spectrum EconOscillator
Absolute Maximum Ratings
Voltage Range on V
Voltage Range on Input Pins
Relative to Ground............................... -0.5V to (V
Relative to Ground .........-0.5V to +6.0V
Operating Temperature Range........................... -40°C to +85°C
Storage Temperature Range............................ -55°C to +125°C
Soldering Temperature......................................See IPC/JEDEC
J-STD-020A Specification
CC
+ 0.5V),
CC
not to exceed 6.0V
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 = -40°C to +85°C)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
3.0
TYP
MAX
UNITS
Supply Voltage
V
CC
(Note 1)
5.5
V
0.7 x
V
+
CC
0.3
Input Logic 1 (J0, J1, JC0, JC1)
Input Logic 0 (J0, J1, JC0, JC1)
V
V
V
IH
V
CC
+0.3 x
V
V
-0.3
IL
CC
DC Electrical Characteristics
(V
= +3.0V to +5.5V, T = -40°C to +85°C, unless otherwise noted.)
A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
1.4
MAX
UNITS
C = 15pF, V
= 3.3V, R
= 5.5V, R
= 40kΩ
= 40kΩ
L
CC
CC
SET
SET
Supply Current
I
mA
CC
C
= 15pF, V
= -4mA
1.7
3
L
I
OH
High-Level Output Voltage (OUT)
Low-Level Output Voltage (OUT)
V
OH
V
OL
I
IH
2.4
V
V
V
CC
= min
I
= 4mA
0.4
OL
High-Level Input Current
(J0, J1, JC0, JC1)
V
= V
+1.0
µA
IH
IL
CC
= 0V
= max
Low-Level Input Current
(J0, J1, JC0, JC1)
I
V
V
-1.0
µA
µA
IL
Resistor Current
I
150
RES
CC
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
AC Electrical Characteristics
(V
= +3.0V to +5.5V, T = -40°C to +85°C, unless otherwise noted.)
A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Internal Master Oscillator
Frequency
f
4.0
8.0
MHz
MOSC
V
= 3.3V,
= +25°C
CC
Output Frequency Tolerance
Voltage Frequency Variation
Temperature Frequency Variation
∆f
∆f
∆f
-3.0
-0.5
+3.0
+0.5
%
%
%
%
OUT
OUT
OUT
T
A
T
= +25°C, R
= 3.0V to 3.6V (Notes 2, 3)
= 60kΩ,
A
SET
V
CC
T
= +25°C, R
= 4.5V to 5.5V (Notes 2, 3)
= 60kΩ,
A
SET
-1.25
-2.0
+1.25
+2.0
V
CC
V
= 3.3V
CC
(Notes 2, 3, 4)
J0 = GND, J1 = GND
0
2
4
8
J0 = V , J1 = GND
CC
J0 = GND, J1 = V
Peak-to-Peak Dither (3σ)
(Note 5)
CC
CC
J0 = V , J1 = V
CC
t
t
+
POR
Power-Up Time
(Note 6)
0.1
0.5
ms
pF
%
STAB
Load Capacitance
Output Duty Cycle
Output Rise/Fall Time
C
(Note 7)
30
55
L
4MHz to 8MHz, T = +25°C (Note 3)
A
45
<4MHz (Note 4)
50
t , t
C = 15pF
20
ns
R
F
L
Note 1: All voltages referenced to ground.
Note 2: This is the change observed in output frequency due to changes in temperature or voltage.
Note 3: See the Typical Operating Characteristics section.
Note 4: Parameter is guaranteed by design and is not production tested.
Note 5: This is a percentage of the output period. Parameter is characterized but not production tested. This can be varied from 0%
to 8%.
Note 6: This indicates the time between power-up and the outputs becoming active. An on-chip delay is intentionally introduced to
allow the oscillator to stabilize. t
output frequency.
is equivalent to ~500 clock cycles and is dependent upon the programmed
STAB
Note 7: Output voltage swings can be impaired at high frequencies combined with high output loading.
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
Typical Operating Characteristics
(V
= +3.3V, T = +25°C, unless otherwise noted.)
CC
A
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT
vs. OUTPUT LOADING
1.70
1.50
1.30
1.10
0.90
0.70
0.50
4
3
2
1
0
NO LOAD, T = +25°C
A
NO LOAD, V = 3.3V
CC
T
= +25°C, R
= 40kΩ
A
SET
5V
40kΩ
1.45
40kΩ
4V
3V
60kΩ
80kΩ
1.20
0.95
0.70
60kΩ
80kΩ
3.0
3.5
4.0
4.5
5.0
5.5
-40
-15
10
35
60
85
5
10
15
20
25
30
35
40
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
LOAD CAPACITANCE (pF)
OUTPUT VOLTAGE HIGH
vs. OUTPUT CURRENT
OUTPUT VOLTAGE LOW
vs. OUTPUT CURRENT
OUTPUT FREQUENCY
vs. SUPPLY VOLTAGE
10
9
3.1
3.0
2.9
2.8
2.7
0.4
0.3
0.2
0.1
0
T
A
= +25°C
V
= 3.0V
V
= 3.0V
CC
CC
40kΩ
8
7
60kΩ
80kΩ
6
5
4
3.0
3.5
4.0
4.5
5.0
5.5
-5
-4
-3
-2
-1
0
0
1
2
3
4
5
SUPPLY VOLTAGE (V)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
Typical Operating Characteristics (continued)
(V
= +3.3V, T = +25°C, unless otherwise noted.)
CC
A
RESISTOR CURRENT
vs. RESISTOR VALUE
DUTY CYCLE
vs. TEMPERATURE
OUTPUT FREQUENCY
vs. TEMPERATURE
10
18
16
14
12
10
8
52
51
50
49
48
R
= 40kΩ
V
= 3.3V
SET
CC
V
= 3.3V, T = +25°C
A
CC
9
8
7
6
5
4
40kΩ
V
= 3.3V
CC
60kΩ
80kΩ
V
= 5V
10
CC
DS1090U-1
-15
-40
-15
10
35
60
85
40
50
60
(kΩ)
70
80
-40
35
60
85
TEMPERATURE (°C)
R
TEMPERATURE (°C)
SET
FREQUENCY ERROR
vs. SUPPLY VOLTAGE (FROM 3.3V)
FREQUENCY ERROR
vs. TEMPERATURE (FROM +25°C)
POWER SPECTRUM vs. SPREAD
5.0
2.5
0
2.0
1.0
0
0
-10
-20
-30
-40
-50
-60
-70
-80
V
T
= 3.3V,
= +25°C,
CC
OFF
T
= +25°C
V
= 3.3V
CC
A
60kΩ
A
JC0 = JC1 = 1
2%
80kΩ
4%
8%
80kΩ
-2.5
-5.0
-1.0
-2.0
40kΩ
60kΩ
40kΩ
3.0
3.5
4.0
4.5
5.0
5.5
-40
-15
10
35
60
85
4.80
5.35
5.90
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
FREQUENCY (MHz)
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
Pin Description
PIN
1
NAME
FUNCTION
OUT Oscillator Output
2
R
Frequency Control Resistor Input
Positive-Supply Terminal
Ground
SET
3
V
CC
4
GND
J0
5
Dither Amplitude (Percentage) Inputs
(see Table 2)
6
J1
7
JC0
JC1
Dither Rate Divisor Inputs (see Table 1)
8
Block Diagram
DS1090
R
SET
VOLTAGE-
BIAS CIRCUIT
MASTER
OSCILLATOR
(VCO)
FACTORY
PROGRAMMED
PRESCALER
+
f
f
f
OUT
MOSC
OSC
BUFFER
OUT
∑
+
( 1, 2, 4, 8, 16, OR 32)
4MHz–8MHz
V
CC
V
CC
DITHER GENERATOR
+
-
DITHER
AMPLITUDE
TRIANGLE
GENERATOR
DITHER RATE
GND
f
(0, 2, 4, OR 8%)
( 128)
( 4, 8, 16, OR 32)
MOD
J0
J1
JC0
JC1
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
MASTER OSCILLATOR FREQUENCY vs.
EXTERNAL RESISTOR SELECTION
IF DITHER AMOUNT = 0%
(+ 1, 2, or 4% of f
Programmed f
)
MOSC
DITHER
AMOUNT
(2, 4, OR 8%)
9
8
7
6
5
4
3
MOSC
(- 1, 2, or 4% of f
)
MOSC
1
MOD
f
TIME
Figure 2. Center Frequency Dither Diagram
Factory-Programmed Prescaler
The prescaler divides the frequency of the master oscillator
by 1, 2, 4, 8, 16, or 32 to generate the square-wave output
50
80
RESISTANCE (kΩ)
40
60
70
90
R
SET
clock (f
option.
). This divisor is factory-set and is an ordering
OSC
Figure 1. Master Oscillator Frequency
Detailed Description
Dither Generator
The DS1090 is a center-dithered, spread-spectrum silicon
oscillator for use as an external clock in reduced-EMI
applications. With a combination of factory-programmed
prescalers and a user-selected external resistor, output
frequencies from 125kHz to 8MHz can be achieved. The
output center frequency can be dithered by selecting the
desired dither rate and amplitude with discrete inputs J0,
J1, JC0, and JC1.
Spread-spectrum functionality is achieved by a user-
configurable divider (determines dither rate), a triangle
generator, and a user-configurable dither amplitude circuit
(see Block Diagram).
The input to the triangle-wave generator is derived
from the internal master oscillator and is fed through a
user-configurable divider. The settings of control pins JC0
and JC1 determine this dither rate divisor setting (see
Table 1), dividing the master clock by 4, 8, 16, or 32. The
clock signal is further divided by 128 in the triangle-wave
generator, which results in a triangle-wave signal of either
1/512th, 1/1024th, 1/2048th, or 1/4096th of the master
The DS1090 contains four basic circuit blocks: master
oscillator, factory-programmed prescaler, dither generator,
and the voltage-bias circuit that provides the feedback
path to the master oscillator for frequency control and
dithering functions.
oscillator (f
), depending upon the user’s divisor set-
MOD
ting.
Master Oscillator
The master oscillator is programmable in the application
The dithering frequency can be also expressed as the
result of
by the use of an external resistor (R
) tied to ground
SET
(GND). Resistor values of 45kΩ to 91kΩ vary the
square-wave output frequency of the voltage-controlled
f
MOSC
Divisor ×128
f
=
MOD
master oscillator (f
(see Figure 1).
) from 8MHz down to 4MHz
MOSC
where Divisor is 4, 8, 16, or 32.
The master oscillator (Hz) frequency can be stated as
Table 1. Dither Rate Divisor Settings
3.6461E+11
Resistor
f
≅
MOSC
DITHERING PERCENTAGE
DIVISOR
JC1
JC0
(f
/n)
SETTING
MOSC
0
0
1
1
0
1
0
1
f
/512
/1024
/2048
/4096
4
8
MOSC
f
f
f
MOSC
MOSC
MOSC
16
32
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
R
SET
Resistor Selection
Table 2. Dither Percentage Setting
The value of the resistor used to select the desired
frequency is calculated using the formula in the Master
Oscillator section (see also Figure 1). It is recommended
to use, at minimum, a 1%-tolerance, 1/16th-watt component
with a temperature coefficient that satisfies the overall
stability requirements desired of the end-equipment.
J1
0
J0
0
DITHER PERCENT (%)
0
2
4
8
0
1
1
0
1
1
Place the external R
resistor as close as possible to
SET
minimize lead inductance.
Dither Percentage Settings
Dither amplitude (measured in percent ± from the master
oscillator center frequency) is set using input pins J0 and
J1. This circuit uses a sense current from the master
oscillator bias circuit to adjust the amplitude of the tri-
angle-wave signal to a voltage level that modulates the
master oscillator to a percentage of its resistor-set center
frequency. This percentage is set in the end application to
be 0%, 2%, 4%, or 8% (see Table 2).
Power-Supply Decoupling
To achieve best results, it is highly recommended that a
decoupling capacitor is used on the IC power-supply pins.
Typical values of decoupling capacitors are 0.01µF and
0.1µF. Use a high-quality, ceramic, surface-mount capaci-
tor, and mount it as close as possible to the V
pins of the IC to minimize lead inductance.
and GND
CC
Chip Information
SUBSTRATE CONNECTED TO GROUND
Application Information
Pin Connection
The DS1090 is intended to provide a fixed-frequency,
dithered clock to be used as a clock driver for DC-DC
converters and other applications requiring a low-
frequency EMI-reduced clock oscillator. All control pins
must be biased per Tables 1 and 2 for proper operation
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
for the individual application’s requirements. R
must
SET
be tied to ground (GND) by a customer-supplied resistor.
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DS1090
Low-Frequency, Spread-Spectrum EconOscillator
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
DESCRIPTION
CHANGED
1
2
3
2/07
2/15
9/16
—
—
Remove automotive reference from data sheet
1
1
Corrected typo in Benefits and Features section
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2016 Maxim Integrated Products, Inc. │ 9
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