Spread Spectrum Clock synchronizes 8 switching regulators.

Press Release Summary:



Offered in MS16 Package, LTC6909 reduces peak radiated EMI and promotes control (enable/disable/phase-synchronize) of switching regulators in multiphase power supplies. Precision silicon oscillator has 8 separate outputs, providing up to 8 rail-to-rail 50% duty cycle clock signals. Using 3 logic inputs, output phase relationship can be configured from 45-120°. Single resistor selects output frequency (12.5 kHz to 6.67 MHz), and spread spectrum frequency modulation can also be enabled.



Original Press Release:



LTC6909 Spread Spectrum Clock Synchronizes up to 8 Switching Regulators



MILPITAS, CA - March 10, 2009 - Linear Technology announces the LTC6909, a precision silicon oscillator that significantly reduces peak radiated EMI and improves control of switching regulators in multiphase power supplies. The LTC6909 has 8 separate outputs, providing up to 8 rail-to-rail 50% duty cycle clock signals. These outputs can be used to enable or disable and phase-synchronize multiple switching regulators. Phase-synchronization offers a number of design advantages, including improved EMI performance, reduced input and output ripple current, and better load transient response. Using 3 logic inputs, the phase relationship between these outputs can be configured from 45° to 120°, or the outputs can be placed in a logic low or high-Z state.

A single resistor selects the output frequency from 12.5kHz to 6.67MHz. The LTC6909 also offers spread spectrum frequency modulation (SSFM), a technique that modulates the clock frequency by a pseudorandom signal. SSFM is easily enabled and offers a method for decreasing peak electromagnetic emissions. The amount of frequency spreading is fixed at ±10% of the center frequency, and the user selects one of 3 modulation rates.

"Incorporating multiple switching regulators into a single system is much simpler with the LTC6909," says Doug LaPorte, design manager for Linear Technology. "The LTC6909 can be used to enable and disable a bank of regulators, to synchronize their operation for improved efficiency and offer vastly better EMI performance through SSFM."

Fully specified over the temperature range of -40°C to 125°C, the LTC6909 offers rugged and reliable operation, as well as fast startup and low power consumption. These parts are available in a compact 16-lead MSOP package. 1000-piece pricing starts at $2.46 each. For more information, visit www.linear.com.

Summary of Features: LTC6909

8 Clock Outputs Configurable in 8 Phase Settings

One External Resistor Sets the Output Frequency from 12.5kHz to 6.67MHz

Optional Spread Spectrum Frequency for Improved EMI Performance

±10% Frequency Spreading

Outputs Can Be Held Low or Muted (Hi-Z)

600uA Supply Current Typical (V+ = 5V)

Operates from a Single 2.7V to 5.5V Supply

260us Start-Up

First Cycle Accurate

Outputs Are High Impedance Until Frequency Settles

-40°C to 125°C Operating Temperature Range

MS16 Package

About Linear Technology
Linear Technology Corporation, a manufacturer of high performance linear integrated circuits, was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major public companies in 2000. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, uModule(TM) products, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.
LT, LTC and LTM are registered trademarks and uModule is a trademark of Linear Technology Corp. All other trademarks are the property of their respective owners.

Contacts
North America and General Information
John Hamburger
Tel: (408) 432-1900 ext. 2419
jhamburger@linear.com

Doug Dickinson
Tel: (408) 432 1900 ext. 2233
ddickinson@linear.com

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