Electronics Weekly
ISL9120 buck-boost switching regulator
Its adaptive current limit PFM architecture delivers efficiency up to 98%, says the company, with smooth transitions from buck-to-boost to prevent glitches in applications where light load efficiency and fast transient response are critical.
The device is small enough for IoT, 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 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 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 1.41mm x 1.41mm package, designers no longer have to compromise efficiency or form factor.
According to Intersil the ISL9120 offers designers the flexibility to cover a variety of design needs by operating from a Vin of 1.8V to 5.5V and 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, 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.
Key features and specifications are:
• 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 800mA (Vin = 2.5V, Vout = 3.3V)
• 2A switches supports both high and light load currents with high efficiency
• Ultra-small footprint with 1.41mm x 1.41mm package saves board space, requires only a single inductor
• Quiescent current of 41uA maximizes light load efficiency for low power consumption
• Automatic and selectable forced bypass power saving mode reduces quiescent current to less than 0.5uA
• Full protection for under-voltage, short-circuit and over-temperature
The ISL9120 is available in 9-bump WLCSP and QFN packages, and is priced at $0.72 in 1k quantities. Two ISL9120 evaluation boards allow designers to evaluate device features and performance: The ISL9120IIN-EVZ (3.3Vout) is priced at $74.45 and the ISL9120IIA-EVZ (adjustable Vout) is $73.35.
