Detailed Description

The DS1083L modulates an input clock to provide a cen-

ter-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.

Dither-Rate Selection

The output spread-spectrum dither rate is automatically

adjusted depending on the input frequency, to maxi-

mize EMI reduction.

The dither cycle rate is:

On power-up, the output clock (SSO) remains three-

dither rate is selected by sampling the input clock at

power-up.

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 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

16MHz to 134MHz Spread-Spectrum

Clock Modulator for LCD Panels

4

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Pin Description

PIN

NAME

DESCRIPTION

1

CLKIN

2

GND

Ground

3

SSO

Spread-Spectrum Clock Output. Outputs a center-dithered spread-spectrum version of the clock input at

CLKIN.

Spread-Spectrum Magnitude Select Inputs. These digital inputs select the desired spread-spectrum

SMSEL2

SMSEL1

MAGNITUDE SELECTED (%)

4

SMSEL2

0

0

±2

0

1

±1.5

1

0

±1

5SMSEL1

1

1

±0.5

6

VCC

Supply Voltage