Features and Benefits
- ±1.5% LED Current Regulation
- ±1.2% Output Voltage Regulation
- 5000:1/10000+:1 PWM Dimming at 100Hz (LT3932/LT3932-1)
- 128:1 Internal PWM Dimming
- 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
- 99.9% Maximum Duty Cycle
- Analog or Duty Cycle LED Current Control
- Open/Short LED Protection and Fault Indication
- Accurate LED Current Sense with Monitor Output
- Programmable UVLO
- Thermally Enhanced 28-Pin (4mm x 5mm) QFN
The LT3932 is a monolithic, synchronous, step-down DC/DC converter that utilizes fixed-frequency, peak current control and provides PWM dimming for a string of LEDs. The LED current is programmed by an analog voltage or the duty cycle of pulses at the CTRL pin. An output voltage limit can be set with a resistor divider to the FB pin.
The switching frequency is programmable from 200kHz to 2MHz by an external resistor at the RT pin or by an external clock at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI. The LT3932 also includes a driver for an external, high side PMOS for PWM dimming and an internal PWM signal generator for analog control of PWM dimming when an external signal is not available. The LT3932-1 permits higher dimming ratios.
Additional features include an LED current monitor, an accurate EN/UVLO pin threshold, open-drain fault reporting for open-circuit and short-circuit load conditions, and thermal shutdown.
- Automotive Lighting
- Industrial and General Purpose Light
- Machine Vision Systems
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 (1)
Demonstration circuit DC2286A is a 36V, 2A synchronous 2MHz buck LED driver featuring the LT3932. It drives one or two series LEDs at 1A when VIN is between 8V and 36V. It can run down to 4VIN with a single LED (if UVLO is adjusted). DC2286A runs at 2MHz switching frequency. Spread spectrum frequency modulation (SSFM) can be turned on with a simple jumper, reducing EMI. DC2286A comes with low EMI features including optimized layout, SSFM, and input and output filters. It passes CISPR 25 class 5 conducted and radiated EMI. It is protected against both open and short LED conditions and reports the faults.
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
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:
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.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.