Features and Benefits
- Dual 100mV Rail-to-Rail Current Sense Amplifiers
- Wide Input Voltage Range: 2.5V to 25V
- 3A, 42V Internal Switch
- High Efficiency Power Conversion: Up to 93%
- Drives LEDs in Boost, Buck-Boost or Buck Mode
- Frequency Set by External Resistor: 200kHz to 3.5MHz
- Programmable Soft-Start
- Low VCESAT Switch: 0.3V at 2.5A
- Capable of Positive and Negative Output Voltages (Boost, Inverting, SEPIC, Flyback)
- Available in Thermally Enhanced 20-Lead (4mm × 4mm) QFN and 20-Lead TSSOP Packages
The LT3477 is a current mode, 3A DC/DC step-up converter with dual rail-to-rail current sense amplifiers and an internal 3A, 42V switch. It combines a traditional voltage feedback loop and two unique current feedback loops to operate as a constant-current, constant-voltage source. Both current sense voltages are set at 100mV and can be adjusted independently using the IADJ1 and IADJ2 pins. Efficiency of up to 93% can be achieved in typical applications. The LT3477 features a programmable soft-start function to limit inductor current during start-up. Both inputs of the error amplifier are available externally allowing positive and negative output voltages (boost, inverting, SEPIC, Flyback). The switching frequency is programmable from 200kHz to 3.5MHz through an external resistor.
Available in thermally enhanced 20-pin (4mm × 4mm) QFN and 20-pin TSSOP packages, the LT3477 provides a complete solution for both constant-voltage and constantcurrent applications.
- High Power LED Driver
- DSL Modems
- Distributed Power
- Input/Output Current Limited Boost, SEPIC, Inverting, Flyback Converters
- Constant-Voltage, Constant-Current Source
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (2)
Demonstration circuit 841 is a constant current LED boost converter with input current and output voltage protection featuring the LT3477. The board is optimized to drive 330mA LED arrays with a total LED voltage between the maximum input voltage and 36V. The input voltage range is 2.7V to 16V.
DC841 has overvoltage protection below 36V if the LEDs are open or not properly attached to the terminals on the PCB
Documentation & Resources
R303 Reliability Data3/23/2018
3A Converter Drives LEDs with 500:1 Dimming3/1/2006 LT Journal
Constant Current from 3A DC/DC Converter with 2 Rail-to-Rail Current Sense Amplifiers12/1/2005 LT Journal
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
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Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LT3477 Companion Parts
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.
|Part Number||Material Declaration||Reliability Data||Pin/Package Drawing||CAD Symbols, Footprints & 3D Models|
|LT3477EFE#PBF||Material Declaration||Reliability Data||20-Lead TSSOP w/ EP|
|LT3477EFE#TRPBF||Material Declaration||Reliability Data||20-Lead TSSOP w/ EP|
|LT3477EUF#PBF||Material Declaration||Reliability Data||20-Lead QFN (4mm x 4mm x 0.75mm w/ EP)|
|LT3477EUF#TRPBF||Material Declaration||Reliability Data||20-Lead QFN (4mm x 4mm x 0.75mm w/ EP)|
|LT3477IFE#PBF||Material Declaration||Reliability Data||20-Lead TSSOP w/ EP|
|LT3477IFE#TRPBF||Material Declaration||Reliability Data||20-Lead TSSOP w/ EP|
|LT3477IUF#PBF||Material Declaration||Reliability Data||20-Lead QFN (4mm x 4mm x 0.75mm w/ EP)|
|LT3477IUF#TRPBF||Material Declaration||Reliability Data||20-Lead QFN (4mm x 4mm x 0.75mm w/ EP)|
|Wafer Fabrication Data||R303 Reliability Data|
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Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.