Micropower No R Constant Frequency Step-Down DC/DC Controller

The LTC3772B is a constant frequency current mode step-down DC/DC controller in a low profile 8-lead SOT-23 (ThinSOT™) and a 3mm × 2mm DFN package. The No RSENSE™ architecture eliminates the need for a current sense resistor, improving efficiency and saving board space.

The LTC3772B automatically switches into pulse skipping operation at light loads. It consumes only 200μA of quiescent current under a no-load condition.

The LTC3772B incorporates an undervoltage lockout feature that shuts down the device when the input voltage falls below 2V. To maximize the runtime from a battery source, the external P-channel MOSFET is turned on continuously in dropout (100% duty cycle). High switching frequency of 550kHz allows the use of a small inductor and capacitors. An internal soft-start smoothly ramps the output voltage from zero to its regulation point.

Burst Mode

LTC3772

Yes

LTC3772B

No

Applications

* 1- or 2-Cell Li-Ion Battery-Powered Applications

* Wireless Devices

* Portable Computers

* Distributed Power Systems

* No Current Sense Resistor Required

* High Output Currents Easily Achieved

* Internal Soft-Start Ramps VOUT

* Wide VIN Range: 2.75V to 9.8V

* Low Dropout: 100% Duty Cycle

* Constant Frequency 550kHz Operation

* Low Ripple Pulse Skipping Operation at Light Load