DS1090 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – Low-Frequency, Spread-Spectrum EconOscillator

Rev 0; 4/04
Low-Frequency, Spread-Spectrum
EconOscillator
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
Typical Operating Circuit
Features
♦ Low-Cost, Spread-Spectrum EconOscillator™
♦ Simple User Programming
♦ Output Frequency Programmable from 125kHz
to 8MHz
♦ Dither Percentage Programmable from 0% to 8%
♦ Dither Rate Programmable (f_MOSC / 512, 1024,
2048, or 4096 )
♦ 3.0V to 5.5V Single-Supply Operation
♦ CMOS/TTL-Compatible Output
♦ Operating Temperature Range: -40°C to +85°C
Ordering Information
PART
OUTPUT
FREQUENCY
RANGE
PRESCALER
PIN-
PACKAGE
DS1090U-1 4MHz to 8MHz
1
8 µSOP
DS1090U-2* 2MHz to 4MHz
2
8 µSOP
DS1090U-4* 1MHz to 2MHz
4
8 µSOP
DS1090U-8* 500kHz to 1MHz
8
8 µSOP
DS1090U-16 ^{250kHz to}
500kHz
16
8 µSOP
DS1090U-32* ^{125kHz to}
250kHz
Add “/T” for Tape & Reel orders.
*Contact factory for availability.
32
8 µSOP
Pin Configuration
V_IN
45kΩ
TO 91kΩ
V_CC
V_{CC OUT}
JC0
DS1090 ^JC1
R_SET
J0
J1
GND
DC-DC
STEP-DOWN
CONVERTER
V_OUT
TOP VIEW
OUT 1
R_SET 2
V_CC 3
GND 4
DS1090
µSOP
8 JC1
7 JC0
6 J1
5 J0
EconOscillator is a trademark of Dallas Semiconductor.
______________________________________________ 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.