LTC6908-1/LTC6908-2

1

690812fa

690812 TA01b

FREQUENCY

(FUNDAMENTAL AND HARMONICS SHOWN)

150kHz

0

–10

–20

–30

–40

0

–10

–20

–30

–40

30MHz

SSFM DISABLED

SSFM ENABLED

Resistor Set SOT-23

Oscillator with Spread

Spectrum Modulation

provides 2-outputs, shifted by either 180° or 90°. The

oscillator frequency is programmed by a single external

(SSFM) can be activated for improved electromagnetic

compatibility (EMC) performance.

The LTC6908 operates with a single 2.7V to 5.5V supply

and provides rail-to-rail, 50% duty cycle square wave

outputs. A single resistor from 10k to 2M is used to select

an oscillator frequency from 50kHz to 10MHz (5V supply).

The oscillator can be easily programmed using the simple

formula outlined below:

The LTC6908’s SSFM capability modulates the output

frequency by a pseudorandom noise (PRN) signal to

decrease the peak electromagnetic radiation level and

improve EMC performance. The amount of frequency

spreading is fixed at ±10% of the center frequency. When

SSFM is enabled, the rate of modulation is selected by the

for Improved EMC Performance

(2mm

× 3mm) Packages

APPLICATIO S

FEATURES

DESCRIPTIO

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

2.25MHz, 2.5V/8A Step-Down Regulator

TYPICAL APPLICATIO

44.2k

OUT1

OUT2

MOD

GND

SET

690812 TA01a

LTC3418

100

µF

0.2

µH

LTC6908-1

RUN/SS

PGOOD

SW

PGND

SGND

820pF

1000pF

0.1

µF

100

µF

×2

2.5V

8A

4.32k

2k

41.2k

2.2M

2.8V TO 5.5V

4.99k

150kHz to 30MHz Output

Frequency Spectrum

(9kHz Res BW)