Micropower Buck Regulator with Integrated Boost and Catch Diodes

The LT3470A is a micropower step-down DC/DC converter that integrates a 440mA power switch, catch diode and boost diode into low profile 2mm × 3mm DFN package. The LT3470A combines Burst Mode and continuous operation to allow the use of tiny inductor and capacitors while providing a low ripple output to loads of up to 250mA.

With its wide input range of 4V to 40V, the LT3470A can regulate a wide variety of power sources, from 2-cell Li-Ion batteries to unregulated wall transformers and lead-acid batteries. Quiescent current in regulation is just 35µA in a typical application while a zero current shutdown mode disconnects the load from the input source, simplifying power management in battery-powered systems. Fast current limiting and hysteretic control protects the LT3470A and external components against shorted outputs, even at 40V input. The LT3470A has higher output current and improved start-up and dropout performance compared to the LT3470.

Vin Min Startup

Switch Current

LT3470

5.5V

300mA

LT3470A

4V

400mA

Applications

* Automotive Battery Regulation

* Power for Portable Products

* Distributed Supply Regulation

* Industrial Supplies

* Wall Transformer Regulation

* Low Quiescent Current: 35µA at 12VIN to 3.3VOUT

* Integrated Boost and Catch Diodes

* Input Range: 4V to 40V

* 3.3V at 250mA from 4V to 40V Input

* 5V at 250mA from 5.7V to 40V Input

* Low Output Ripple: <10mV

* <1µA in Shutdown Mode

* Output Voltage: 1.25V to 16V