Analog Devices LT3575EFE | Demoboard DC1643A

Description

Demonstration circuit 1643A is an isolated flyback converter featuring LT®3575, a monolithic switching regulator specifically designed for the isolated flyback converter with an integrated 2.5A, 60V NPN transistor. The DC1643A is designed for 5V output from a 10V to 28V DC input.

The output current capability depends on the input voltage, proper cooling, and the switch voltage stress. The output current is up to 1.4A when the input is higher than 10V, and 2A when the input is higher than 20V but lessthan 28V. The output current should not be higher than 2.4A for safe operation.

The IC requires minimum load to maintain good output voltage regulation. A Zener diode D4 across the outputclamps the voltage to ~5.4V. The light load regulation can be improved if a preload resistor (R4, optional) is installed. Depending on input voltage and output regulation, a 40mAminimum load is usually sufficient.

The DC1643A can be easily modified to generate different output voltages. Some pre-designed transformers from vendors such as Würth Electronics, Sumida, Pulse Engineering and Coilcraft, can be used for various applications.

The LT3575 operates with input supply voltages from 3V to 40V. The part senses the isolated output voltage directly from the primary side flyback waveform. No third winding or opto-coupler is required for regulation.The LT3575 utilizes boundary mode operation to provide a high efficiency, small size solution with improved load regulation. It can be used in industrial, automotive and medical applications where an isolated output is required.

The LT3575 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this quick start guide for DC1643A.

More information

• Datasheet
• IC product information