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DS1081L

20MHz to 134MHz Spread-Spectrum

Clock Modulator for LCD Panels

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Maxim Integrated Products

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.

General Description

The DS1081L 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

DS1081L 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 and dither rate, allowing direct

EMI control and optimization. In addition, through an

enable pin the dithering can be enabled or disabled for

easy comparison of system performance during EMI test-

ing. This same input pin also allows the DS1081L output

to be three-stated.

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 asso-

ciated with mechanical shielding.

The DS1081L 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

Automotive Telematics and Infotainment

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 Power Consumption

♦ 3.3V Single Voltage Supply

♦ -40°C to +125°C Temperature Range

♦ Small 8-Pin TSSOP Package

19-6013; Rev 1; 10/11

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

T = Tape and reel.

Ordering Information

PART TEMP RANGE PIN-PACKAGE

DS1081LE+ -40°C to +125°C 8 TSSOP

DS1081LE+T -40°C to +125°C 8 TSSOP

Block Diagram

GND

SSO

PLL WITH CENTER-

DITHERED

SPREAD

SPECTRUM

CONFIGURATION

DECODE AND

CONTROL

SMSEL1

CLKIN

SMSEL2

SSO

= 20MHz to

134MHz (DITHERED)

= 20MHz TO

134MHz

CRSEL

SSEN

ENABLE

LOGIC

DS1081L

Typical Operating Circuit appears at end of data sheet.

SSO

GND

7 CRSELSMSEL1

SMSEL2

CLKIN

TOP VIEW

SSEN

DS1081L

Pin Configuration

Summary of content (6 pages)

PAGE 1
9-6013; Rev 1; 10/11 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels The DS1081L 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 DS1081L accepts an input clock signal in the range of 20MHz to 134MHz and delivers a spread-spectrum modulated output clock signal.
PAGE 2
DS1081L 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels ABSOLUTE MAXIMUM RATINGS Voltage Range on VCC Relative to GND .............-0.5V to +3.63V Voltage Range on Any Pin Relative to GND ................-0.5V to (VCC + 0.5V), not to exceed +3.63V Operating Temperature Range .........................-40°C to +125°C Continuous Power Dissipation (TA = +70°C) TSSOP (derate 8.1mW/°C above +70°C) ..................646.7mW Storage Temperature Range .............................
PAGE 3
20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels SUPPLY CURRENT vs. SUPPLY VOLTAGE 8 CLKIN = 20MHz 6 4 3.1 3.2 3.3 3.4 3.5 CLKIN = 33MHz 6 4 VCC = 3.6V 10 8 VCC = 3.0V 6 4 2 0 -40 -20 3.6 0 20 40 60 80 100 120 20 36 56 76 96 116 134 FREQUENCY (MHz) DUTY CYCLE vs. TEMPERATURE DUTY CYCLE vs. SUPPLY VOLTAGE SPECTRUM ATTENUATION vs.
PAGE 4
20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels DS1081L Pin Description PIN NAME 1 CLKIN 2 SMSEL1 3 FUNCTION Clock Input. 20MHz 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. SMSEL2 SMSEL1 MAGNITUDE SELECTED 0 0 ±2.0% 0 1 1 0 ±1.5% ±1.0% 1 1 ±0.5% SMSEL2 4 GND Ground 5 SSEN Spread-Spectrum Enable.
PAGE 5
20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels 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 capacitor, and mount it as close as possible to the VCC and GND pins of the IC to minimize lead inductance. IF SSEN = 1 fIN + (0.5%, 1.0%, 1.5%, OR 2.0% OF fIN) DITHER AMOUNT (±0.5%, ±1.0%, ±1.5%, OR ±2.
PAGE 6
DS1081L 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels Revision History REVISION NUMBER REVISION DATE 0 4/07 1 10/11 DESCRIPTION Initial release PAGES CHANGED — Updated the Absolute Maximum Ratings, Recommended Operating Conditions, and DC Electrical Characteristics; corrected pin number error in the Pin Description; added the Package Information table 2, 4, 5 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.