Rainbow Electronics DS1081L User Manual

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Rev 0; 4/07

20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels

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 modulated 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 testing. This same input pin also allows the DS1081L output to be tri-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 associated 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.

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

Applications

LCD Panels for TVs, Desktop Monitors, and Notebook and Tablet PCs

Automotive Telematics and Infotainment

Printers

Pin Configuration and Typical Operating Circuit appear at end of data sheet.

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

 

 

 

DS1081LE+

-40°C to +125°C

8 TSSOP

 

 

 

DS1081LE+T

-40°C to +125°C

8 TSSOP

 

 

 

+Denotes lead-free package. T Denotes tape-and-reel.

 

Block Diagram

 

Pin Configuration

 

VCC

 

TOP VIEW

 

 

 

 

 

 

 

 

 

 

DS1081L

VCC

 

 

 

 

CLKIN

PLL WITH CENTER-

SSO

CLKIN

1

8

VCC

fIN = 20MHz TO

DITHERED

 

 

 

 

 

SPREAD

fSSO = 20MHz to

 

 

 

 

134MHz

SMSEL1

2

7

CRSEL

SPECTRUM

134MHz (DITHERED)

 

 

 

SMSEL2

3

DS1081L

SSO

 

ENABLE

SSEN

6

 

 

 

 

 

 

LOGIC

 

GND

4

5

SSEN

 

 

 

CRSEL

CONFIGURATION

 

 

 

 

 

SMSEL1

 

 

 

 

 

DECODE AND

GND

 

 

 

 

SMSEL2

 

 

TSSOP

 

CONTROL

 

 

 

 

 

 

 

 

 

(4.40mm)

 

DS1081L

______________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

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

Storage Temperature Range

.............................-55°C to +125°C

Voltage Range on Any Lead Relative

 

Soldering Temperature...................

See J - STD - 020 Specification

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

CONDITIONS

MIN

TYP

MAX

UNITS

 

 

 

 

 

 

 

Supply Voltage

VCC

(Note 1)

3.0

 

3.6

V

Input Logic 1

VIH

 

0.8 x

 

VCC +

V

 

VCC

 

0.3

 

 

 

 

 

 

 

 

 

 

 

 

Input Logic 0

VIL

 

-0.3

 

0.2 x

V

 

 

VCC

 

 

 

 

 

 

 

 

 

 

 

 

 

Input Logic Float (SSEN, CRSEL)

VFLOAT

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

%

 

 

 

 

 

 

 

DC ELECTRICAL CHARACTERISTICS

(VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

 

 

 

 

 

 

 

Supply Current

ICC

CL = 7pF

 

 

15

mA

fIN = 134MHz

 

 

 

 

 

 

 

 

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

AC ELECTRICAL CHARACTERISTICS

(VCC = +3.0V to +3.6V, 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

tR

CL = 7pF

 

1

 

ns

SSO Fall Time

tF

CL = 7pF

 

1

 

ns

Peak Cycle-to-Cycle Jitter

tJ

TA = -40°C to +85°C, 10,000 cycles

 

75

 

ps

Power-Up Time

tPOR

(Note 2)

 

 

50

ms

 

 

 

 

 

 

 

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.

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