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

The LT3645 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.

Applications

* Automotive CMOS Image Sensors

* Industrial/Automotive Micro-Controller Supply

* 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