LT3935

Name: LT3935
Brand: Analog Devices
Price: 3.32 USD
Availability: InStock

RECOMMENDED FOR NEW DESIGNS

36V, 4A Synchronous Step-Down LED Driver with Silent Switcher

Data Sheet (Rev. C) Product Selection Table

Part Models: 1
1ku List Price: Starting From $3.32

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Overview

±1.5% LED Current Regulation
±1.2% Output Voltage Regulation
Spread-Spectrum Frequency Modulation
Silent Switcher^® Architecture for Low EMI
3.6V to 36V Input Voltage Range
0V to 36V LED String Voltage

200kHz to 2MHz with SYNC Function
20:1 Analog or Duty Cycle LED Current Control
Open/Short LED Fault Indication
Accurate LED Current Sense with Monitor Output
Programmable UVLO
Thermally Enhanced 28-Lead (5mm × 4mm) LQFN

Part Models: 1
1ku List Price: Starting From $3.32

Documentation

Data Sheet 1

LT3935: 36V, 4A Synchronous Step-Down LED Driver with Silent Switcher Data Sheet (Rev.C) 11/05/2024

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 Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT3935RV#PBF	28-Lead QFN (5mm x 4mm x 0.94mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Feb 20, 2025 - 25_0023 LT3935- Die thickness Change
		PCN25_0023_Form Material_Report
LT3935RV#PBF	PRODUCTION	PCN25_0023_Form Material_Report

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Tools & Simulations

LTspice 1

LT3935 - 40V<sub>IN</sub> 36V<sub>OUT</sub> 4A Synchronous Buck LED Driver with Silent Switcher

Models for the following parts are available in LTspice:

LT3935

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.

Evaluation Kits

LT3935 Demo Board | 36V, 4A Synchronous Buck LED Driver with Silent Switcher

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Product Details

Demonstration circuit 2987A is a 36V, 4A synchronous 2MHz buck LED driver featuring the LT3935. This demonstration circuit powers one or two LEDs at 4A. DC2987A runs from an input voltage of 8V to 36V as built and can run down to 3.6V_IN if UVLO is adjusted. It runs at 2MHz switching frequency. With Spread Spectrum Frequency Modulation (SSFM) turned on, it runs from 2MHz to 2.5MHz. An optional low-side NMOS PWM dimming MOSFET can be used for a high PWM dimming ratio. DC2987A features undervoltage lockout (UVLO) set at 7V with 0.7V hysteresis for turn-on. This Silent Switcher^® demo circuit features low emissions.

The LT3935 has an input voltage range from 3.6V to 36V. It has internal, synchronous 5.8A, 40V switches for high power, and high efficiency with a single IC. It has an adjustable switching frequency between 200kHz and 2MHz. It can be synchronized (SYNC) to an external source or run with SSFM for low EMI.

The LT3935 can be PWM dimmed for accurate brightness control. An optional low-side MOSFET can be driven from the PWM input source for high and accurate dimming ratio. However, LED– can be connected directly to GND for the least components. In this arrangement, PWM dimming has less range. Analog dimming is accomplished by driving the CTRL pin with a voltage below 1.5V to lower the LED sense voltage.

Small ceramic input and output capacitors save space and cost. The open LED overvoltage protection uses the IC’s constant-voltage regulation loop to regulate the output to approximately 9V if the LED string is opened. Then a fault flag is asserted. The output current can be monitored through the ISMON output pin.

The UVLO voltage, LED current, output voltage range, switching frequency, brightness control, and SSFM can all be adjusted with simple modifications to the demo circuit. The LT3935 data sheet gives a complete description of the device, operation and applications information. The data sheet must be read in conjunction with this demo manual for DC2987A. The LT3935JV is assembled in a 28-lead 5mm × 4mm LQFN package with a thermally enhanced GND.