DC1725A: 5V @ 2A, 1.8 ~ 4.5V in, Boost

Summary

The LT3759 is a current mode DC/DC controller operating over an input range of 1.6V to 42V, making it well suited for applications ranging from single-cell lithium-ion battery portable electronics to high voltage automotive and industrial power supplies. It also exhibits low shutdown quiescent current of 1μA, making it an ideal fit for battery operated systems.

Thanks to a novel FBX pin architecture, the LT3759 can be connected directly to a divider from either a positive or negative output feedback voltage to ground. It also packs many popular features such as softstart, input undervoltage lockout, adjustable frequency and synchronization in a small 12-lead exposed pad MSOP package.

Demonstration circuit 1725A features LT3759 in a 485 kHz boost converter, designed for a 5V/2A output from a 1.8V to 4.5V input. The demo circuit configures the shutdown voltage at typical 1.70V, which means that the input voltage can be dropped to as low as 1.70V, once it starts up. The start-up voltage is set at 2.5V but can be adjusted by changing R1 and R2 values.

The LT3759 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.

Specifications

Manufacturer	Analog Devices Inc.
Category	AC/DC and DC/DC Conversion
Sub-Category	DC/DC SMPS - Single Output
Eval Board Part Number	505-DC1725A-ND
Eval Board Supplier	Analog Devices Inc.
Eval Board	Normally In Stock
Topology	Step Up
Outputs and Type	1 Non-Isolated
Voltage Out: Factory Set	5 V
Current Out	2 A
Voltage In	1.8 ~ 4.5 V
Efficiency @ Conditions	>88%, 4.5V in, 5V @ 0.6 ~ 2 A >85%, 2.5V in, 5V @ 0.6 ~ 2 A >80%, 1.8V in, 5V @ 0.36 ~ 2 A
Voltage Out Range	4.85 ~ 5.15 V
Features	Current Limit (Adj. or Fixed) Power Good Output Short Circuit Protection Shutdown, Enable, Standby Soft Start Synchronizable Under Voltage Protection, Brown-Out
Switching Frequency	485 kHz
Standby Current [Typical]	100 nA
Quiescent Current [Typical]	2 mA
Component Count + Extras	21 + 13
Internal Switch	Yes
Design Author	Linear Technology
Application / Target Market	Automotive Portable Devices Power: Auxiliary Power Supply
Standby Current [Maximum]	1 µA
Quiescent Current [Maximum]	2.5 mA
Main I.C. Base Part	LT3759
Date Created By Author	2011-08
Date Added To Library	2015-05