Download DS1083L 16MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels General Description

Rev 0; 5/07
16MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
The DS1083L 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
DS1083L accepts an input clock signal in the range of
16MHz to 134MHz and delivers a spread-spectrum
modulated output clock signal. The PLL modulates, or
dithers, the output clock about the center input frequency at a pin-selectable magnitude. The DS1083L automatically adjusts the dither rate based on the input
clock frequency to maximize the EMI reduction.
By dithering the system clock, all the address, data,
and timing signals generated from this signal are also
dithered so that the measured EMI at the fundamental
and harmonic frequencies is greatly reduced. This is
accomplished without changing clock rise/fall times or
adding the space, weight, design time, and cost associated with mechanical shielding.
The DS1083L is provided in a low-cost, space-saving,
6-lead thin SOT23 package and operates over a full
automotive temperature range of -40°C to +125°C.
Features
♦ Modulates a 16MHz to 134MHz Clock with Center
Spread-Spectrum Dithering
♦ Selectable Spread-Spectrum Modulation
Magnitudes of:
±0.5%
±1%
±1.5%
±2%
♦ Low 75ps Cycle-to-Cycle Jitter
♦ Automatic Dither Cycle Rate Adjustment to
Maximize EMI Reduction
♦ Low Cost
♦ Low Power Consumption
♦ 3.3V Single Voltage Supply
♦ -40°C to +125°C Operating Temperature Range
♦ Small 6-Lead Thin SOT23 Package
Applications
LCD Panels for TVs, Desktop Monitors, Notebook
and Tablet PCs
Automotive Telematics and Infotainment
Ordering Information
PART
TEMP RANGE
DS1083LR+T
-40°C to +125°C
PIN-PACKAGE
6 Thin SOT23
+Denotes a lead-free package.
T = Tape and reel.
Printers
Pin Configuration and Typical Operating Circuit appear at
end of data sheet.
Block Diagram
DS1083L
CLKIN
fIN = 16MHz TO
134MHz
SSO
PLL WITH CENTERSPREAD
DITHERING
VCC
fSSO = 16MHz to
134MHz (DITHERED)
VCC
VCC
RPU
RPU
SMSEL1
CLOCK RATE
DETECT
CONFIGURATION
DECODE AND
CONTROL
GND
SMSEL2
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1
DS1083L
General Description
DS1083L
16MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
ABSOLUTE MAXIMUM RATINGS
Storage Temperature Range .............................-55°C to +125°C
Soldering Temperature...........................Refer to the IPC/JEDEC
J-STD-020 Specification.
Voltage Range on VCC Relative to GND.............-0.5V to +3.63V
Voltage Range on Any Lead Relative
to GND ................-0.5V to (VCC + 0.5V), not to exceed +3.63V
Operating Temperature Range .........................-40°C to +125°C
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 OPERATING CONDITIONS
(TA = -40°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL
MAX
UNITS
3.0
3.6
V
VIH
0.7 x
VCC
VCC +
0.3
V
SMSEL1/SMSEL2 Input Logic 0
VIL
-0.3
0.3 x
VCC
V
SSO Load
CL
VCC Supply Voltage
VCC
SMSEL1/SMSEL2 Input Logic 1
CONDITIONS
(Note 1)
MIN
TYP
f SSO < 80MHz
15
80MHz f SSO < 134MHz
7
pF
CLKIN Frequency
f IN
16
134
MHz
CLKIN Duty Cycle
f INDC
40
60
%
VCC Power-Up Time
t PV
200
ms
MAX
UNITS
15
mA
GND to VCCMIN
DC ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
Supply Current
ICC
CL = 7pF,
f IN = 134MHz
SMSEL1/SMSEL2 Pullup Resistance
R PU
TA = +25°C
SMSEL1/SMSEL2 Input Leakage
I IL
MIN
60
Low-Level Output Voltage (SSO)
VOL
0V < VIN < VCC
I OL = 4mA
High-Level Output Voltage (SSO)
VOH
I OH = -4mA
TYP
100
140
k
±80
μA
0.4
V
2.4
V
AC ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
SSO Duty Cycle
f SSODC
Measured at VCC/2
SSO Rise Time
tR
CL = 7pF
SSO Fall Time
tF
Peak Cycle-to-Cycle Jitter
tJ
MIN
TYP
MAX
40
60
%
1
ns
CL = 7pF
1
ns
TA = -40°C to +85°C, 10,000 cycles
75
ps
Note 1: All voltages referenced to ground. Currents into the IC are positive and currents out of the IC are negative.
2
UNITS
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16MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
CLKIN = 16MHz
4
2
3.1
3.2
3.3
3.4
3.5
4
3.6
VCC = 3.6V
8
VCC = 3.0V
6
4
2
0
-40 -20
0
20
40
60
80
16
100 120
36
56
76
96
134
116
FREQUENCY (MHz)
DUTY CYCLE vs. TEMPERATURE
DUTY CYCLE vs. SUPPLY VOLTAGE
SPECTRUM ATTENUATION vs. FREQUENCY
AT DIFFERENT DITHER AMPLITUDES
60
DS1083L toc04
56
DUTY CYCLE (%)
54
52
50
48
54
52
50
48
46
46
44
44
42
42
40
CLKIN = 66MHz
58
±1%
0.5%
±1.5%
±2%
fOUT = 40MHz
3dB
ATTENUATION (dB)
CLKIN = 66MHz
DS1083L toc06
TEMPERATURE (°C)
DS1083L toc05
SUPPLY VOLTAGE (V)
56
DUTY CYCLE (%)
CLKIN = 16MHz
0
3.0
58
8
6
10
2
0
60
CLKIN = 66MHz
SUPPLY CURRENT (mA)
8
6
CLKIN = 134MHz
10
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
CLKIN = 66MHz
12
DS1083L toc02
DS1083L toc01
CLKIN = 134MHz
10
SUPPLY CURRENT vs. FREQUENCY
SUPPLY CURRENT vs. TEMPERATURE
12
DS1083L toc03
SUPPLY CURRENT vs. SUPPLY VOLTAGE
12
6dB
4.5dB
fOUT = 40MHz
RBW = 120kHz
CENTER DITHER
40
-40 -20
0
20
40
60
TEMPERATURE (°C)
80
100 120
3.0
3.1
3.2
3.3
3.4
SUPPLY VOLTAGE (V)
3.5
3.6
FREQUENCY (MHz)
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3
DS1083L
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
16MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
DS1083L
Pin Description
PIN
NAME
DESCRIPTION
1
CLKIN
2
GND
Ground
SSO
Spread-Spectrum Clock Output. Outputs a center-dithered spread-spectrum version of the clock input at
CLKIN.
3
4
SMSEL2
5
SMSEL1
6
VCC
Clock Input. 16MHz to 134MHz clock input (fIN).
Spread-Spectrum Magnitude Select Inputs. These digital inputs select the desired spread-spectrum
magnitude as shown in the table below. Both inputs contain pullup resistors (RPU) to VCC.
SMSEL2
0
SMSEL1
0
MAGNITUDE SELECTED (%)
±2
0
1
±1.5
1
0
±1
1
1
±0.5
Supply Voltage
Detailed Description
The DS1083L modulates an input clock to provide a center-dithered spread-spectrum output. A 16MHz to
134MHz clock is applied to the CLKIN pin. The PLL
dithers the output clock about its center frequency at a
user-selectable magnitude. The user is required to cycle
power to the device each time there is a change in the
input frequency, for the PLL to lock correctly. This
ensures proper output frequency and dither rate. The
desired spread-spectrum magnitude is selected using
input pins SMSEL1 and SMSEL2 (see the Pin Description
for details). The DS1083L is capable of generating
spread-spectrum clocks from 16MHz to 134MHz.
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, surfacemount capacitor, and mount it as close as possible to
the VCC and GND pins of the IC to minimize lead
inductance.
Chip Information
SUBSTRATE CONNECTED TO GROUND
Dither-Rate Selection
The output spread-spectrum dither rate is automatically
adjusted depending on the input frequency, to maximize EMI reduction.
The dither cycle rate is:
fIN/512, if fIN is between 16MHz and 33MHz
fIN/1024, if fIN is between 33MHz and 64MHz
fIN/2048, if fIN is between 64MHz and 134MHz
On power-up, the output clock (SSO) remains threestated until it reaches a stable frequency (fSSO). The
dither rate is selected by sampling the input clock at
power-up.
4
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16MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
DS1083L
IF DITHER AMOUNT = 0%
fIN + (0.5%, 1%, 1.5%, OR 2% OF fIN)
DITHER AMOUNT
(±0.5%, ±1%, ±1.5%, OR ±2%)
fIN
fIN - (0.5%, 1%, 1.5%, OR 2% OF fIN)
1
fSSO
DITHER CYCLE
RATE*
TIME
*DITHER CYCLE RATE =
fIN/512, IF fIN = 16MHz TO 33MHz
fIN/1024, IF fIN = 33MHz TO 64MHz
fIN/2048, IF fIN = 64MHz TO 134MHz
Figure 1. Spread-Spectrum Frequency Modulation
Typical Operating Circuit
VCC
fIN = 16MHz TO
134MHz
CLKIN
GND
fSSO
SSO
VCC
DS1083L
SMSEL1
DECOUPLING
CAPACITOR
SMSEL2
DITHERED
NOTE: IN THE ABOVE CONFIGURATION WITH SMSEL1 CONNECTED TO VCC AND SMSEL2 CONNECTED
TO GND, THE DEVICE WILL HAVE A SPREAD-SPECTRUM MAGNITUDE OF ±1.5%.
Package Information
Pin Configuration
For the latest package outline information, go to
www.maxim-ic.com/packages.
TOP VIEW
+
CLKIN 1
GND 2
DS1083L
SSO 3
6
VCC
5
SMSEL1
4
SMSEL2
PACKAGE TYPE
DOCUMENT NO.
6 Thin SOT23
21-0114
THIN SOT23
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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is a registered trademark of Maxim Integrated Products, Inc.
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