High-efficiency buck-boost and boost+bypass switching regulators

October 07, 2014 // By Graham Prophet
Intersil has expanded its ISL911xx family of buck-boost and boost switching regulators for system power supplies and peripherals such as Wi-Fi or 3G/4G RF power amplifiers, featuring efficiency of up to 96% and providing smooth transitions from buck to boost to prevent glitches and noise in single-cell lithium ion (Li-ion) or Li-polymer battery systems.

The ISL9110x buck-boost regulator family is capable of working with ultra-small inductors and capacitors to fit within less than 14 mm² board footprint, yielding a 2A switching converter solution for space-constrained mobile devices. The wafer-level CSP package requires only a single inductor and very few external components. The ISL911xx regulators' 2.5MHz switching frequency further reduces the power supply solution size.

ISL91106 and ISL91107 buck-boost regulators offer a wide input range (1.8V - 5.5V) and integrated 3.6A switches that deliver up to 2x faster transient response than the closest competitor. This enables mobile devices to handle large current bursts from spikes in power consumption without significant output disturbance. The 2A output buck-boost converters permit reliable system operation under all load conditions, and enable higher efficiency power supplies that occupy less PCB space. When input is close to output the product automatically transitions between bypass and buck-boost operating modes without output disturbance. This maximises the power efficiency of the system. The ISL91106 also includes a selectable forced bypass function for sleep mode or an ultra-low-power mode that permits the system to stay alive with nearly zero quiescent current.

The ISL91132, ISL91133 and ISL91134 high-efficiency boost regulators offer a true bypass feature that can be used in any single cell application where the input voltage can vary from above or below the target output voltage. The ISL91132 (>1.8A) and ISL91133 (>2.3A) maintain the required output voltage for critical system functions when the input battery voltage is subject to large transients. The low no-load quiescent current significantly reduces standby power consumption. The ISL91134 (>1.8A) regulator's soft-start ramp feature, and boost to 5V, makes it suitable for use with Class-D audio amplifiers. All three of the boost regulators can run in an auto-bypass mode or in forced bypass operation via a selection pin.

ISL91106 and ISL91107 buck-boost switching regulators cost $1.90; ISL91132, ISL91133 and ISL91134 boost+bypass regulators cost $1.80 (1000).

Intersil; www.intersil.com/isl911xx-buck-boost-regulators