SOT -23 Oscillator printed circuit board timer circuit with Spread Spectrum Modulation

SOT -23 Oscillator printed circuit board timer circuit with Spread Spectrum Modulation

Resistor Set SOT-23 Oscillator with Spread Spectrum Modulation

FEATURES

■ LTC6908-1: Complementary Outputs (0°/180°)

■ LTC6908-2: Quadrature Outputs (0°/90°)

■ 50kHz to 10MHz Frequency Range

■ One External Resistor Sets the Frequency

■ Optional Spread Spectrum Frequency Modulation for Improved EMC Performance

■ ±10% Frequency Spreading

APPLICATIO S

■ Switching Power Supply Clock Reference

■ Portable and Battery-Powered Equipment

■ Precision Programmable Oscillator

■ Charge Pump Driver

DESCRIPTIO U

The LTC®6908 is an easy-to-use precision oscillator that provides 2-outputs, shifted by either 180° or 90°. The oscillator frequency is programmed by a single external resistor (RSET) and spread spectrum frequency modulation (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:

fOUT =10MHz • 10k/RSET

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 fi xed at ±10% of the center frequency. When SSFM is enabled, the rate of modulation is selected by the user. The three possible modulation rates are fOUT/16, fOUT/32 and fOUT/64.

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