General Description
The DS1181L is a spread-spectrum clock modulator IC
that reduces EMI in high clock-frequency-based, digital
electronic equipment.
Using an integrated phase-locked loop (PLL), the
DS1181L accepts an input clock signal in the range of
20MHz to 134MHz and delivers a spread-spectrum mod-
ulated output clock signal. The PLL modulates, or dithers,
the output clock about the center input frequency at a
pin-selectable magnitude, allowing direct EMI control and
optimization. In addition, through an enable pin the dith-
ering can be enabled or disabled for easy comparison of
system performance during EMI testing. This same input
pin also allows the DS1181L output to be three-stated.
By dithering the system clock, all the address, data, and
timing signals generated from this signal are also dith-
ered so that the measured EMI at the fundamental and
harmonic frequencies is greatly reduced. This is accom-
plished without changing clock rise/fall times or adding
the space, weight, design time, and cost associated with
mechanical shielding.
The DS1181L is provided in an 8-pin TSSOP package
and operates over a full automotive temperature range of
-40°C to +125°C.
Applications
●LCD Panels for TVs, Desktop Monitors, and
Notebook and Tablet PCs
●Printers
Features
●Modulates a 20MHz to 134MHz Clock with Center
Spread-Spectrum Dithering
●Selectable Spread-Spectrum Modulation
Magnitudes of:
±0.5%
±1.0%
±1.5%
±2.0%
●Low 75ps Cycle-to-Cycle Jitter
●Spread-Spectrum Disable Mode
●Pin Compatible with Alliance/PulseCore
Semiconductor P2040 Series Devices
●Clock Output Disable
●Low Cost
●Low Power Consumption
●3.3V Single Voltage Supply
●-40°C to +125°C Temperature Range
●Small 8-Pin TSSOP Package
19-7502; Rev 2; 2/15
Typical Operating Circuit appears at end of data sheet.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
PART TEMP RANGE PIN-PACKAGE
DS1181LE+ -40°C to +125°C 8 TSSOP
DS1181LE+T -40°C to +125°C 8 TSSOP
SSO
GND
1
2
8
7 CRSELSMSEL1
SMSEL2
CLKIN
TSSOP
TOP VIEW
3
4
6
5
VCC
SSEN
DS1181L
+
GND
SSO
PLL WITH CENTER-
DITHERED
SPREAD-
SPECTRUM
CONFIGURATION
DECODE AND
CONTROL
SMSEL1
CLKIN
SMSEL2
fSSO = 20MHz to
134MHz (DITHERED)
VCC
VCC
fIN = 20MHz TO
134MHz
CRSEL
SSEN
ENABLE
LOGIC
DS1181L
Pin Conguration
Ordering Information
Block Diagram
DS1181L 20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
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 VCC Relative to GND .............-0.5V to +4.3V
Voltage Range on Any Lead Relative
to GND ................-0.5V to (VCC + 0.5V), not to exceed +4.3V
Operating Temperature Range ......................... -40°C to +125°C
Storage Temperature Range ............................ -55°C to +125°C
Soldering Temperature ..................See J-STD-020 Specification
Note 1: All voltages referenced to ground. Currents into the IC are positive and out of the IC are negative.
Note 2: Time between power applied to device and stable output.
(VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.)
(VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.)
(TA = -40°C to +125°C, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SSO Duty Cycle fSSODC Measured at VCC/2 40 60 %
SSO Rise Time tRCL = 7pF 1 ns
SSO Fall Time tFCL = 7pF 1 ns
Peak Cycle-to-Cycle Jitter tJTA = -40°C to +85°C, 10,000 cycles 75 ps
Power-Up Time tPOR (Note 2) 50 ms
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Current ICC CL = 7pF, fIN = 134MHz 18 mA
SMSEL1/SMSEL2/CLKIN Input Leakage IIL:1 0V < VIN < VCC -1 +1 µA
CRSEL/SSEN Input Leakage IIL:2 0V < VIN < VCC -100 +100 µA
Output Leakage (SSO) IOZ SSEN = float -1 +1 µA
Low-Level Output Voltage (SSO) VOL IOL = 4mA 0.4 V
High-Level Output Voltage (SSO) VOH IOH = -4mA 2.4 V
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage VCC (Note 1) 3.0 3.6 V
Input Logic 1 VIH
0.8 x
VCC
VCC +
0.3 V
Input Logic 0 VIL -0.3 0.2 x
VCC
V
Input Logic Float (SSEN, CRSEL) IFLOAT 0V < VIN < VCC ±1 µA
SSO Load CL
SSO < 80MHz 15 pF
80MHz ≤ SSO < 134MHz 7
CLKIN Frequency fIN 20 134 MHz
CLKIN Duty Cycle fINDC 40 60 %
AC Electrical Characteristics
DC Electrical Characteristics
Recommended Operating Conditions
Absolute Maximum Ratings
DS1181L 20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
www.maximintegrated.com Maxim Integrated
│
2
SPECTRUM ATTENUATION vs. FREQUENCY AT
DIFFERENT DITHER AMPLITUDES
DS1181L toc06
FREQUENCY (MHz)
ATTENUATION (dB)
fOUT = 72MHz
fRBW = 120KHz
CENTER DITHER
±2%
±1.5% ±1%
±0.5%
10dB 13dB 15dB 17dB
DUTY CYCLE vs. TEMPERATURE
DS1181L toc05
TEMPERATURE (°C)
DUTY CYCLE (%)
1106010
42
44
46
48
50
52
54
56
58
60
40
-40
fCLKIN = 72MHz
DUTY CYCLE vs. SUPPLY VOLTAGE
DS1181L toc04
VCC (V)
DUTY CYCLE (%)
3.53.43.33.23.1
42
44
46
48
50
52
54
56
58
60
40
3.0 3.6
fCLKIN = 72MHz
SUPPLY CURRENT vs. FREQUENCY
DS1181L toc03
FREQUENCY (MHz)
ICC (mA)
120100806040
2
4
6
8
10
12
0
20
CL = 7pF
VCC = 3.6V
VCC = 3.0V
SUPPLY CURRENT vs. TEMPERATURE
DS1181L toc02
TEMPERATURE (°C)
ICC (mA)
1106010
2
4
6
8
10
12
0
-40
fCLKIN = 134MHz
fCLKIN = 20MHz
CL = 7pF
fCLKIN = 66MHz
SUPPLY CURRENT vs. SUPPLY VOLTAGE
DS1181L toc01
VCC (V)
ICC (mA)
3.53.43.33.23.1
2
4
6
8
10
12
0
3.0 3.6
fCLKIN = 134MHz
fCLKIN = 20MHz
CL = 7pF
fCLKIN = 66MHz
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
DS1181L 20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
Maxim Integrated
│
3
www.maximintegrated.com
Detailed Description
The DS1181L modulates an input clock to generate a cen-
ter-dithered spread-spectrum output. A 20MHz to 134MHz
clock is applied to the CLKIN pin. An internal PLL dithers
the output clock about its center frequency at a user-se-
lectable magnitude.
Spread-Spectrum Dither Magnitude
The DS1181L can generate dither magnitudes up to
±2%. The desired magnitude is selected using input pins
SMSEL1 and SMSEL2 as shown in Table 1.
Spread-Spectrum Dither Rate
The output spread-spectrum dither rate is fixed at fIN/832.
Table 2. Dither Rate
Table 1. Dither Magnitude
CRSEL CLKIN RANGE
(MHz) DITHER RATE
0 66 to 134
fIN/832Float 33 to 80
1 20 to 38
SMSEL2 SMSEL1 MAGNITUDE
SELECTED (%)
0 0 ±2.0
0 1 ±1.5
1 0 ±1.0
1 1 ±0.5
PIN NAME FUNCTION
1 CLKIN Clock Input. 20MHz to 134MHz clock input (fIN).
2 SMSEL1
Spread-Spectrum Magnitude Select Inputs. These digital inputs select the desired spread-spectrum
magnitude as shown in the table below.
SMSEL2 SMSEL1 MAGNITUDE SELECTED (%)
0 0 ±2.0
3 SMSEL2
0 1 ±1.5
1 0 ±1.0
1 1 ±0.5
4 GND Ground
5SSEN
Spread-Spectrum Enable. Three-level input to enable/disable spread-spectrum and to three-state the
output.
0 = Power-up/spread-spectrum enabled
Float = SSO three-stated
1 = Power-up/spread-spectrum disabled (not a bypass mode).
6 SSO Spread-Spectrum Clock Output. Outputs a center-dithered spread-spectrum version of the clock input at
CLKIN.
7 CRSEL
Clock Range and Dither Rate Select. Three-level input that determines the dither rate. See the
Detailed Description section for details.
CRSEL CLKIN RANGE (MHz) DITHER RATE
0 66 to 134
fIN/832
Float 33 to 80
1 20 to 38
8 VCC Supply Voltage
Pin Description
DS1181L 20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
www.maximintegrated.com Maxim Integrated
│
4
Spread-Spectrum Enable
On power-up, the output clock (SSO) remains three-stat-
ed until the internal PLL reaches a stable frequency. The
SSEN input can be used to disable the spread-spectrum
modulation and to three-state the SSO output. If the SSEN
pin is pulled high, the spread-spectrum modulation is
turned off, but the device still uses the internal PLL to gen-
erate the clock signal at SSO. If the SSEN pin is floated,
the output is three-stated.
Applications Information
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 VCC and GND
pins of the IC to minimize lead inductance.
Figure 1. DS1181L Spread-Spectrum Frequency Modulation
PACKAGE TYPE PACKAGE CODE DOCUMENT NO. LAND PATTERN NO.
8 TSSOP H8+3 21-0175 90-0248
CLKIN
SMSEL1
SMSEL2
GND
CRSEL
VCC
DECOUPLING
CAPACITOR
VCC
SSO
fIN = 20MHz TO
134MHz
NOTE: IN THE ABOVE CONFIGURATION WITH SMSEL1, SMSEL2, AND SSEN CONNECTED TO GND AS WELL AS
CRSEL CONNECTED TO VCC, THE DEVICE IS CONFIGURED WITH A SPREAD-SPECTRUM MAGNITUDE OF 2.0%,
AND ALLOWS A CLKIN BETWEEN 20MHz and 38MHz.
fSSO
DITHERED
SSEN
DS1181L
fIN + (0.5%, 1.0%, 1.5%, OR 2.0% OF fIN)
fIN
fIN - (0.5%, 1.0%, 1.5%, OR 2.0% OF fIN)
fSSO
TIME
1
DITHER CYCLE
RATE
DITHER AMOUNT
(±0.5%, ±1.0%, ±1.5%, OR ±2.0%)
CLKIN RANGE (MHz) DITHER RATE
20 TO 134 fIN/832
IF SSEN = 1
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.
Typical Operating Circuit
DS1181L 20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
www.maximintegrated.com Maxim Integrated
│
5
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 11/07 Initial release. —
1 8/08 Increased the absolute maximum ratings range from +3.63V to +4.3V. 2
2 2/15 Removed automotive reference from data sheet 1
Revision History
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2015 Maxim Integrated Products, Inc.
│
6
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 specications 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.
DS1181L 20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
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.
