Mobiles/wearables targeted by efficient 800 mA buck-boost chip

July 07, 2015 // By Graham Prophet
Intersil’s ISL9120, is a buck-boost switching regulator that enables efficient power management of system power supplies and peripherals. Its adaptive current limit PFM architecture delivers efficiency up to 98%, while providing smooth transitions from buck-to-boost to prevent glitches in applications where light load efficiency and fast transient response are critical.

An ultra-small form factor suits the ISL9120 for connected devices including wearables, smartphones, smart thermostats and point-of-sale devices that run on single-cell Li-ion or Li-polymer batteries, or 2-cell alkaline, NiCd or NiMH batteries.

Typical power solutions for wearables, Intersil asserts, use three DC-DC regulators and 3-5 LDOs, which takes up valuable board space. LDOs also lack the high efficiency and reliability of a buck-boost regulator. For example, when LDOs are used to power peripherals in a system running on a Li-ion battery with Vout near 3.3V, a large burst of current demanded by the applications processor can cause Vin to droop below the LDO regulation voltage, causing a memory reset or application shutdown. The ISL9120 buck-boost switching regulator eliminates this problem by addressing a wider Vin range and providing boost to avoid low voltage glitches that can cause a battery brownout when the Vin droops below the output voltage. Requiring only a single inductor and available in a small 1.41 x 1.41 mm package, designers no longer have to compromise efficiency or form factor.

The ISL9120 operates from a Vin of 1.8V to 5.5V and generates an adjustable output voltage from 1V to 5.2V. Its adaptive PFM operation with forced bypass mode and 2A switches support both low load and high load currents with high efficiency. The regulator also delivers 800 mA current with 2.5V input and 3.3V output. During system stay-alive conditions when regulation is not required, the ISL9120 goes into forced bypass mode, which reduces power consumption to a quiescent current of less than 0.5 µA.

Features and specifications include;

• Ultra high efficiency up to 98% reduces power drain and heat buildup

• Accepts a wide input voltage range from 1.8V to 5.5V, works with multiple battery topologies

• Large adjustable output voltage range from 1V to 5.2V for use with multiple power rails

• Output current up to 800 mA (Vin = 2.5V, Vout =