General Description

The DS1090 is a low-cost, dithered oscillator intended

to be used as an external clock for switched-mode

power supplies and other low-frequency applications.

The dithering or sweeping function reduces peak-radi-

ated emissions from the power supply at its fundamen-

tal frequency, as well as harmonic frequencies. The

device consists of a resistor-programmed master oscil-

lator, factory-programmed clock prescaler, and a pin-

programmed dither circuit. These features allow the

DS1090 to be used in applications where a spread-

spectrum clock is desired to reduce radiated emis-

sions. A combination of factory-set prescalers and

external resistor allows for output frequencies ranging

from 125kHz to 8MHz. Both dither frequency and dither

percentage are set using control pins.

Applications

Switched-Mode Power Supplies

Servers

Printers

Embedded Microcontrollers

Industrial Controls

Automotive Applications

Features

♦ Low-Cost, Spread-Spectrum EconOscillator™

♦ Simple User Programming

♦ Output Frequency Programmable from 125kHz

to 8MHz

♦ Dither Percentage Programmable from 0% to 8%

2048, or 4096 )

♦ 3.0V to 5.5V Single-Supply Operation

♦ CMOS/TTL-Compatible Output

♦ Operating Temperature Range: -40°C to +85°C

Low-Frequency, Spread-Spectrum

EconOscillator

______________________________________________ Maxim Integrated Products

1

J1

J0

GND

1

2

8

7

JC1

JC0

OUT

µSOP

TOP VIEW

3

4

6

5

DS1090

Pin Configuration

Ordering Information

DS1090

DC-DC

STEP-DOWN

CONVERTER

OUT

GND

JC0

JC1

J0

J1

45k

Ω

TO 91k

Ω

Typical Operating Circuit

Rev 0; 4/04

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.

Add “/T” for Tape & Reel orders.

*Contact factory for availability.

PART

OUTPUT

FREQUENCY

RANGE

PRESCALER

PIN-

PACKAGE

DS1090U-1

4MHz to 8MHz

18 µSOP

DS1090U-2*

2MHz to 4MHz

28 µSOP

DS1090U-4*

1MHz to 2MHz

48 µSOP

DS1090U-8*

500kHz to 1MHz

88 µSOP

DS1090U-16

250kHz to

500kHz

16

8 µSOP

DS1090U-32*

125kHz to

250kHz

32

8 µSOP

EconOscillator is a trademark of Dallas Semiconductor.