High current buck-boost regulators target portable/mobile designs

August 16, 2016 // By Graham Prophet
Intersil claims up to 96% efficiency and the lowest quiescent current for its ISL91127 and ISL91128 devices, and has configured them for low-voltage, battery-operated systems.

The parts are high efficiency buck-boost regulators that feature 4.5A switches, efficiency up to 96%, and a compact footprint providing system power or powering peripherals in battery-operated devices. Quiescent current is 30µA for superior light load efficiency.


For hand-held device applications where the input voltage may be higher or lower than the output voltage, and with demands for smaller and smaller footprints, QFN and WLCSP packages enable power designs that maximize efficiency while providing flexibility. The regulators operate in buck, boost or buck-boost mode, depending on the relation between input and output voltages, and provide smooth transitions between modes to prevent noise and glitches.


The buck-boost regulators’ input voltage range of 1.8V to 5.5V supports multiple battery topologies, and their output voltage range of 1V to 5.2V combined with 3A output current provide flexibility. The ISL91128 also features I ²C programmable dynamic output voltage adjustability, which eliminates feedback resistors and allows the reuse of the same design for multiple output voltage needs. 96% efficiency is reached at (PVIN = 3.6V, Vout = 3.4V~4V, Iout = 200 mA); output current up to 3A is available in boost mode (PVIN = 3V, Vout = 3.3V). The input voltage can range from 1.8 to 5.5V, output voltage can be adjustable or fixed at 3.3V; ther is protection for under-voltage, short-circuit, and thermal faults.


The ISL91127IR in a 4 x 4 mm, 20-pin QFN package is priced at $1.29 (1000). ISL91127/ ISL91128 in a 20-bump, 2.15 x 1.74 mm WLCSP package is priced at $1.25. The ISL91127IRN-EVZ fixed 3.3V evaluation board and ISL91127IRA-EVZ adjustable voltage evaluation board are available.


Intersil; www.intersil.com/products/isl91127 / www.intersil.com/products/isl91128