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

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.

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
Applications
  • Automotive CMOS Image Sensors
  • Industrial/Automotive Micro-Controller Supply
Packaging
LT3645 Package Drawing
LT3645 Package Drawing
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LT3645EMSE#PBFMS-12EE$3.36$2.35
LT3645EMSE#TRPBFMS-12EE$2.41
LT3645EUD#PBF3x3 QFN-16E$3.22$2.25
LT3645EUD#TRPBF3x3 QFN-16E$2.31
LT3645HMSE#PBFMS-12EH$4.06$2.84
LT3645HMSE#TRPBFMS-12EH$2.90
LT3645IMSE#PBFMS-12EI$3.70$2.59
LT3645IMSE#TRPBFMS-12EI$2.65
LT3645IUD#PBF3x3 QFN-16I$3.54$2.48
LT3645IUD#TRPBF3x3 QFN-16I$2.54
Demo Boards
Part NumberDescriptionPrice
DC1428ALT3645EMSE Demo Board | VIN = 5V to 36V, VOUT1 = 3.3V @ 300mA, VOUT2= 2.5V @ 200mA$125.00
Datasheet
Reliability Data
Press Release
CAD Symbol
LTspice
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