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LT3645 - 36V 500mA Step-Down Regulator and 200mA LDO

Features

  • Wide Input Range:
    Operation from 3.6V to 36V
    Overvoltage Lockout Protects Circuit Through 55V Transients on Input
  • 500mA Output Current Switching Regulator
  • High Switching Frequency: 750kHz
  • 200mA Low Dropout Linear Regulator
    1.2V to 16V Input; 0.8V to 8V Output
    310mV Dropout Voltage VCC2 to OUT2
  • Precision Programmable Undervoltage Lockout
  • Short-Circuit Robust
  • Internal Soft-Start
  • <2μA Shutdown Current
  • Small Thermally Enhanced 16-Lead (3mm × 3mm) QFN and 12-Lead MSE Packages

Typical Application

LT3645 Typical Application
LT3645 Typical Application

Description

The LT®3645 is a dual output regulator combining a 500mA buck regulator and a 200mA low dropout linear regulator (LDO). The wide input voltage range of 3.6V to 36V makes the LT3645 suitable for regulating power from a wide variety of sources, including 24V industrial supplies and automotive batteries. Its high operating frequency allows the use of tiny, low cost inductors and capacitors, resulting in a very small solution.

Cycle-by-cycle current limit and frequency foldback provide protection against shorted outputs. Soft-start and frequency foldback eliminate input current surge during start-up.

The linear regulator operates from the VCC2 pin at voltages down to 1.2V. It supplies 200mA of output current with a typical dropout voltage of 310mV.

Other features of the LT3645 include a <2μA shutdown, short circuit protection, soft-start and thermal shutdown. The LT3645 is available in the thermally enhanced 16-lead (3mm × 3mm) QFN package, or a 12-lead MSE package.

Packaging

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

QFN-16, MS-12

LT3645 Package Drawing
LT3645 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LT3645EMSE#PBF MSOP 12 E $3.36 $2.35 View
LT3645EMSE#TRPBF MSOP 12 E $2.41 View
LT3645EUD#PBF QFN 16 E $3.22 $2.25 View
LT3645EUD#TRPBF QFN 16 E $2.31 View
LT3645HMSE#PBF MSOP 12 H $4.06 $2.84 View
LT3645HMSE#TRPBF MSOP 12 H $2.90 View
LT3645IMSE#PBF MSOP 12 I $3.70 $2.59 View
LT3645IMSE#TRPBF MSOP 12 I $2.65 View
LT3645IUD#PBF QFN 16 I $3.54 $2.48 View
LT3645IUD#TRPBF QFN 16 I $2.54 View
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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
DC1428A LT3645EMSE Demo Board u VIN = 5V to 36V, V OUT1 = 3.3V @ 300mA, V OUT2= 2.5V @ 200mA $125.00
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Click here to view our complete list of demo boards

Applications

  • Automotive CMOS Image Sensors
  • Industrial/Automotive Micro-Controller Supply

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Related models available in LTspice IV
LT3645

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