LTC3808 - Low EMI, Low Noise DC/DC Controller with On-Chip Spread Spectrum Modulation

LTC News for Immediate Release
For more information, tel. 408-432-1900
Doug Dickinson, Media Relations Mgr., ext. 2233
www.linear.com
Low EMI, Low Noise DC/DC Controller with
On-Chip Spread Spectrum Modulation
MILPITAS, CA – April 6, 2005 – Linear Technology Corporation introduces the
LTC3808, a step-down synchronous DC/DC controller with integrated spread spectrum
frequency modulation for systems requiring very low EMI and low noise power supply.
The LTC3808 minimizes the need for EMI shields and filters by randomly varying the
switching frequency from 460kHz to 635kHz, reducing the peak radiated and conducted
noise of the DC/DC controller alternatively by more than 20dB when operating the
LTC3808 at a constant switching frequency. The device provides two options:
user-selectable 300kHz, 550kHz or 750kHz operating frequency or 250kHz to 750kHz
phase-lock loop (PLL) operation. The LTC3808 is ideal for use in applications such as
navigation systems, wireless LAN, data acquisition boards and industrial/military radio
devices.
The LTC3808 converts input voltages of 2.75V to 9.8V to output voltages as low as
0.6V up to VIN. The LTC3808 drives external complementary power MOSFETs with
synchronous operation for high efficiency DC-to-DC conversion. The controller can deliver
as much as 5A to the load while operating at 90% efficiency.
Although the LTC3808 features a current mode architecture, it improves efficiency
and reduces system cost by eliminating the need for a sense resistor by sensing the voltage
across the external MOSFETs. Another feature of the LTC3808 is its output voltage
tracking for controlled supply ramps or the sequencing of multiple supplies. With low input
voltage operation, low dropout and low supply current, the device is ideal for wireless
battery powered devices.
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Low EMI, Low Noise DC/DC Controller with
On-Chip Spread Spectrum Modulation
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The LTC3808 is offered in two packages, a low profile (0.75mm) 4mm x 3mm
DFN and a 16-lead SSOP. The device is rated for operation from -40°C to 85°C. Pricing
starts at $2.60 each for 1,000-piece quantities.
Summary of Features: LTC3808
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Spread Spectrum Modulation for Low EMI Operation
PLL and Adjustable Fixed Frequency Operation
Programmable Output Voltage Tracking
Sense Resistor is Optional
0.6V ±1.5% Reference
Internal Soft-Start
COMPANY BACKGROUND: Linear Technology Corporation was founded in 1981 as a
manufacturer of high performance linear integrated circuits. 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, 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.
For more information, contact:
Doug Dickinson, Media Relations Manager
Linear Technology Corporation
1630 McCarthy Boulevard
Milpitas, CA 95035-7417
[email protected]
408-432-1900
READER SERVICE: Call toll-free 1-800-4-LINEAR (for literature only), or go to the
company’s web site: http://www.linear.com
Note: LT, LTC, and
are registered trademarks of Linear Technology Corp.
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