By Alix Paultre, contributing editor

Analog Devices’ Power by
Linear LTM4661 is a low-power step-up µModule regulator in a 6.25 x 6.25 x 2.42-mm
BGA package. Only a few capacitors and one resistor are required to complete
the design, and the solution occupies less than 1 cm² on single-sided or 0.5 cm² on double-sided PCBs. Incorporating a
switching DC/DC controller, MOSFETs, inductors, and supporting components, the
LTM4661 operates from a 1.8-V to 5.5-V input supply and continues to operate
down to 0.7 V after start-up. The output voltage can be set by a single
resistor ranging from 2.5 V to 15 V.

synchronous-rectification LTM4661 can deliver up to 4 A continuously with an
efficiency as high as 92%. The switching frequency is 1 MHz and can also be
synchronized to an external clock ranging from 500 kHz to 1.5 MHz. There is a
burst mode in which quiescent current is only 25 µA, and for applications
demanding the lowest possible noise operation, a forced continuous mode or
external sync mode minimizes possible interference of switching noise.

The LTM4661 features an output disconnect during shutdown and inrush
current limit at start-up. Fault protection features include short-circuit,
overvoltage, and overtemperature protection. The LTM4661 operates from –40°C to 125°C operating