Datasheet LTC6909 (Analog Devices)

LTC6909 1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation
FeAtures Description
n
1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-Phase Outputs
The LTC®6909 is an easy to use precision oscillator that n
One External Resistor Sets the Output Frequency
can provide 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-phase synchro-
from 12.5kHz to 6.67MHz
nized outputs. The LTC6909 also offers spread spectrum n
Optional Spread Spectrum Frequency for Improved
frequency modulation (SSFM), which can be enabled to im-
EMI Performance
prove electromagnetic compatibility (EMC) performance. n
±10% Frequency Spreading
Eight separate outputs provide up to eight rail-to-rail, n
Outputs Can Be Held Low or Floated (Hi-Z)
50% duty cycle clock signals. Using three logic inputs, the n Three Spread Spectrum Modulation Rates outputs are configured for phase separation, ranging from fOUT/16, fOUT/32 and fOUT/64 45° to 120° (three to eight phases). The clock outputs can n 400µA Supply Current also be held low or configured for Hi-Z. A single resistor, n Operates from a Single 2.7V to 5.5V Supply combined with the phase configuration, sets the output n Fast Start-Up Time frequency, based on the following formula: n First Cycle Accurate n f Outputs Are High Impedance Until Frequency Settles OUT = 20MHz • 10k/(RSET • PH) n MS16 Package where PH = 3, 4, 5, 6, 7 or 8 The LTC6909 can be used in applications requiring only
ApplicAtions
one or two output phases. Alternatively, the LTC6908 family of parts provides the same two output signals but n Synchronizing Multiple Switching Power Supplies in a smaller SOT-23 or 2mm × 3mm DFN package. The L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks LTC6908-1 provides complimentary (180°) outputs while and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6342817, 6614313, the LTC6908-2 provides quadrature (90°) outputs. 7417509.
typicAl ApplicAtion 150kHz to 30MHz Output Frequency Spectrum Providing a 4-Phase Synchronizing Clock to LTM Modules (9kHz Res BW)
0 10V TO 14V SSFM DISABLED –10 INTVCC –20 0.1µF S0FT-START LTC6909 LTM4601 –30 V+D OUT1 1.5V 48A OUTPUT (dBc) GND OUT2 –40 TRACKING V+A OUT3 LTM4601-1 –50 71.5k 0.1µF SET OUT4 0 SSFM ENABLED PH0 OUT5 TRACKING –10 SSFM = fOUT/32 PH1 OUT6 LTM4601-1 –20 PH2 OUT7 MOD OUT8 TRACKING –30 LTM4601-1 OUTPUT (dBc) –40 ENABLE SSFM DISABLE SSFM 6909 TA01 –50 150kHz 30MHz FREQUENCY 0.01µF (FUNDAMENTAL AND HARMONICS SHOWN) 6909 TA01b 6909fa 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts