Download LT4180 Product Overview

Linear Technology
Corporation
LT4180 Backgrounder
Tony Armstrong
Director of Product Marketing
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LT4180 Virtual Remote Sense Controller
Background
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Limitations of Remote Voltage Sensing w/ Wires
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Advantages of Virtual Remote Sensing w/o Wires
LT4180
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Definition
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Features & Benefits
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How Does it Work
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How Well Does it Work
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Application Circuits
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Target Markets
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Target Applications
© 2006 Linear Technology
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Remote Sense Background
• Why Remote Sense?
• Voltage drop (IR Losses) in cables and wiring
• IR losses can cause the regulation at the load to exceed its limit
• Remote sense with 2 wires works but has limitations
• Remote Sense Wire Limitations
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Extra wires can be impractical
Less reliable
Higher cost
Not available in 2-wire cables
© 2006 Linear Technology
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LT4180: Virtual Remote Sense – What is it?
© 2006 Linear Technology
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LT4180: VRS Block Diagram and Waveform
NOTE: Voltage at the load is 5V
© 2006 Linear Technology
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LT4180 Virtual Remote Sense Features
• Tight Load Regulation with Highly Resistive Cables without
Requiring Remote Sense Wires
• Compatible with all Conversion Topology’s including Isolated
and Non-Isolated Power Supplies
• VIN Range: 3V to 50V
• Wide VOUT Range: 1.21V to 50V
• 5mA Sink Current Capability to Drive Opto-Coupler
• Accurate ±1% Internal Reference Voltage
• Soft-Correct Reduces Turn-On Transients
• Undervoltage and Overvoltage Protection
• Programmable or Synchronizable Dither Frequency
• Optional Spread Spectrum Dither Frequency
© 2006 Linear Technology
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LT4180: How Does it Work?
• LT4180 forces a current delta of ±5% of the output current
• Square wave current at a programmable dither frequency
• A decoupling capacitor filters out dither current at the load
and is sized for low impedance (AC short) at the programmed
dither frequency
• This results in a voltage equal to 1/10 the drop in the cable
• The LT4180 adjusts the regulation voltage locally at the
regulator output to compensate for the cable drop. This
assures tight regulation at the other end of the cable, where
the load is.
© 2006 Linear Technology
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LT4180 – How Well Does it Work?
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LT4180: Typical Buck Application Schematic
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LT4180: Typical Isolated Application Schematic
© 2006 Linear Technology
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LT4180: Typical Boost (5V12V) Applications Schematic
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LT4180: Package
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LT4180 Typical Applications
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CAT5 & CAT6 Cable Systems
Wall Adaptors
Notebook Computer Power
Remote Surveillance Equipment
Halogen Lighting
Well-Logging
Remote Instrumentation
Battery Charging
PDA’s
© 2006 Linear Technology
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LT4180: Conclusion
• LT4180 is a revolutionary new way to
compensate for wiring and cable voltage drops
• Limitless applications
• Works with any conversion topology
• Numerous features & benefits
© 2006 Linear Technology