LT3922 - 36V, 2A Synchronous Step-Up LED Driver

Features

  • ±2% LED Current Regulation
  • ±2% Output Voltage Regulation
  • 5000:1 PWM Dimming at 100Hz
  • 128:1 Internal PWM Dimming
  • Spread-Spectrum Frequency Modulation
  • Silent Switcher® Architecture for Low EMI
  • Operates in Boost, Buck Mode and Buck-Boost Mode
  • 2.8V to 36V Input Voltage Range
  • Up to 34V LED String Voltage
  • 2A, 40V Internal Switches
  • 200kHz to 2MHz with SYNC Function
  • Analog or Duty Cycle LED Current Control
  • Open/Short LED Protection and Fault Indication
  • Thermally Enhanced 28-Pin (4mm × 5mm) QFN

Typical Application

LT3922 Typical Application
LT3922 Typical Application

Description

The LT®3922 is a monolithic, synchronous, step-up 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. The LT3922 will maintain ±2% current regulation through an external sense resistor over a wide range of output voltages.

The switching frequency is programmable from 200kHz to 2MHz by an external resistor at the RT pin or by an external clock applied at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI. The LT3922 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.

Additional features include an accurate external reference voltage for use with the CTRL and PWM pins, 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.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT3922EUFD#PBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LT3922EUFD#TRPBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LT3922HUFD#PBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT3922HUFD#TRPBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT3922IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT3922IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes


LT3922 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3922EUFD#PBF 4x5 QFN-28 E $5.64 $3.95 Yes
LT3922EUFD#TRPBF 4x5 QFN-28 E $5.70 $4.01 Yes
LT3922HUFD#PBF 4x5 QFN-28 H $6.57 $4.60 Yes
LT3922HUFD#TRPBF 4x5 QFN-28 H $6.63 $4.66 Yes
LT3922IUFD#PBF 4x5 QFN-28 I $6.22 $4.35 Yes
LT3922IUFD#TRPBF 4x5 QFN-28 I $6.28 $4.41 Yes
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* 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 Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC2247A LT3922 Demo Board | Sync Boost LED Driver, 4V ≤ VIN ≤ 28V, VLED = 34V @ Up to 330mA, 2MHz fSWITCH $100.00
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Click here to view our complete list of demo boards

Applications

  • Automotive and Industrial Lighting
  • Machine Vision

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, 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

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice IV:
LT3922

Technical Support