Switching regulator delivers a 98% efficiency

6th July 2015
Siobhan O'Gorman

A buck-boost switching regulator that enables efficient power management of system power supplies and peripherals such as WiFi, Bluetooth, memory cards or LCD modules has been released by Intersil. The ISL9120 features an adaptive current limit PFM architecture, which delivers an efficiency of 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 makes the regulator suitable for the connected devices making up the IoT including wearables, smartphones, smart thermostats and POS devices that run on single-cell Li-ion or Li-polymer batteries, or 2-cell alkaline, NiCd or NiMH batteries.

With the pervasiveness of mobile devices and growing popularity of wearables, power designers are challenged to balance cost, form factor and power efficiency. Typical power solutions for wearables use three DC/DC regulators and three to five LDOs, which takes up valuable board space. LDOs also lack the high efficiency and reliability of a buck-boost regulator, sacrificing performance as well. For example, when LDOs are used to power peripherals in a system running on a Li-ion battery with the Vout near 3.3V, a large burst current from the applications processor can cause the 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 1.41x1.41mm package, designers no longer have to compromise efficiency or form factor.

The regulator offers designers the flexibility to cover a variety of design needs by operating from a Vin of 1.8 to 5.5V and an adjustable output voltage from 1 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, ensuring longer battery life and less heat buildup. The regulator also delivers 800mA 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 miniscule quiescent current of less than 0.5uA.

“Intersil’s innovative adaptive PFM architecture addresses the most critical low power design requirements for wearables and other 4G/WiFi-enabled portable products functioning as IoT connected nodes,” said Andrew Cowell, Senior Vice President, Mobile Power Products, Intersil. “The ISL9120 regulator’s small size, industry leading efficiency, smooth transition between buck and boost modes and rapid transient response to a large load step is extremely attractive to customers.”

The ISL9120 buck-boost regulator is available in 9-bump WLCSP and QFN packages, and is priced at $0.72 and sold in 1,000-piece quantities. Two ISL9120 evaluation boards allow designers to evaluate device features and performance: The ISL9120IIN-EVZ is priced at $74.45 and the ISL9120IIA-EVZ is $73.35.

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