Features

• Accurate 5V Output
• Programmable Cable Drop Compensation
• Programmable Output Current Limit
• Adjustable Output from 5.0V to 6.1V
• Dual Input Feedback Permits Regulation on Output of USB Switch
• Active Load Reduces Output Overshoot
• FLT Flag Indicates Overcurrent on the USB Output
• 1.5ms FLT Flag Delay Filters Hot Plug Events
• USB Output Current Monitor
• Wide Input Rage: Operation from 5V to 35V
• Withstands Input Transient to 60V
• 2.5A Maximum Output Current
• Survives Output Short to GND and Car Battery
• Adjustable Switching Frequency: 300kHz to 2.2MHz
• Synchronizable from 300kHz to 2.2MHz
• Small, Thermally Enhanced 16-Lead MSOP Package

Typical Application

Description

The LT®3697 is a 35V, 2.5A step-down switching regulator designed to power 5V USB applications. A precise output voltage and programmable cable drop compensation maintain accurate 5V regulation at the USB socket connected to the end of a long cable. The accurate, programmable current limit can eliminate the need for a USB power switch and improve system reliability. The provided 180mA active load reduces output overshoot during load transients. Dual feedback allows regulation on the output of a USB switch and limits cable drop compensation to a maximum of 6.1V output, protecting USB devices during fault conditions. A separate 5V output can be taken from the SYS terminal to power auxiliary circuitry such as a USB hub controller. The LT3697 also provides a load current monitor output and an overcurrent fault indicator.

The LT3697 operates from 300kHz to 2.2MHz and withstands input voltage transients up to 60V. The device's output survives shorts to ground and to the battery. A current mode topology is used for fast transient response and good loop stability. Shutdown reduces input supply current to less than 1μA. The LT3697 is available in a 16-lead MSOP package with an exposed pad for low thermal resistance.