The ISL9120 and ISL9120IR are highly integrated buck-boost switching regulators that accept input voltages either above or below the regulated output voltage. The regulator automatically transitions between buck and boost modes without significant output disturbance. They also have automatic bypass functionality. When the input voltage is generally within 1% to 2% of the output voltage, there will be a direct bypass connection between the VIN and VOUT pins.

In addition to the automatic bypass functionality, the ISL9120 and ISL9120IR also have forced bypass functionality with the use of the BYP pin. The device is capable of delivering up to 800mA of output current (VIN = 2.5V, VOUT = 3.3V) and provides excellent efficiency due to its adaptive current limit Pulse Frequency Modulation (PFM) control architecture.

The ISL9120 and ISL9120IR are designed for stand-alone applications and support a 3.3V fixed output voltage or variable output voltages with an external resistor divider. The forced bypass power saving mode can be chosen if voltage regulation is not required. The device consumes less than 3.5µA of current over the operating temperature range in forced bypass mode.

The ISL9120 and ISL9120IR require only a single inductor and very few external components. Power supply solution size is minimized by the ISL9120 1.41mm x 1.41mm WLCSP package and the ISL9120IR 3mm x 3mm 12 Ld TQFN package.


  • Accepts input voltages above or below regulated output voltage
  • Automatic bypass mode functionality
  • Automatic and seamless transitions between buck and boost modes
  • Input voltage range: 1.8V to 5.5V
  • Selectable forced bypass power-saving mode
  • Adaptive multilevel current limit scheme to optimize efficiency at low and high currents
  • Output current: up to 800mA (VIN = 2.5V, VOUT = 3.3V)
  • High efficiency: up to 98%
  • 41μA quiescent current maximizes light-load efficiency
  • Fully protected for over-temperature and undervoltage
  • Small packages
    • ISL9120 - 1.41mm x 1.41mm WLCSP
    • ISL9120IR - 3mm x 3mm 12 Ld TQFN




  • Smartphones and tablets
  • Portable consumer and wearable devices


Design & Development

Boards & Kits

Boards & Kits


ISL9120 High Efficiency Buck-Boost Regulator

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.


Hi, my name is Gaurav Mital. I'm an applications engineer for the Intersil's mobile power product line. Today I'm gonna be talking about a new power product solution which is going to be a good fit for wearables and mobile systems.

Wearables are becoming very popular and system designers are being constantly challenged to create solutions which are smaller, more efficient and cost effective, and Intersil is committed to be a leader in providing solutions for these products.

A typical power solution for a wearable device uses three DC/DC regulators and three to five LDOs depending on the number of applications. As you can see, Intersil's existing power solutions caters to all blocks but we identified a couple of opportunities where using a buck-boost can be more efficient.

How does the buck-boost add value to the system? A lithium-ion battery voltage varies from 4.2V down to 2.7V. For a system which requires 3.3V, a buck-boost regulator helps in utilizing broader range of the battery.

Also, multiple applications in the mobile are powered by the LDOs like the Wi-Fi and the LCD module which gives buck-boost an edge as it provides better efficiency in these conditions.

When the VBAT is near 3.3V, a burst current can cause local node voltage to droop to 2.7V which may shut down the application and this can also be avoided by using a buck-boost regulator.

I'm excited to share that Intersil has developed a new compact, highly efficient, low powered buck-boost regulator ideal for wearable and hand-held applications, the ISL9120.

The ISL9120 operates from 1.8V to 5.5V. The output voltage is adjustable from 1V to 5.2V which provides flexibility to cover a variety of design needs. The adaptive PFM operation helps in getting excellent efficiency and low output ripple. This part is capable of delivering 800mA current with 2.5V in and 3.3V out. It is offered in a 1.4mm x 1.4mm chip scale package.

The ISL9120 offers excellent efficiency for both low load and high load conditions. The adaptive PFM operation helps in attaining up to 98% efficiency at higher loads and more than 86% at lower load conditions. This ensures less power drain and less heat build up which extends the battery life and saves board space by eliminating the need for external heat sinks.

During a systems stay alive condition where regulation is not a must, the power can be put in force bypass mode in which the power consumption reduces to ultra-low quiescent current of less than 0.5μA. As the part is only 1.4mm x 1.4mm, the overall solution size is very small. This helps in getting a very competitive price solution.

The 98% efficiency, low power consumption and ultra-small PCB footprint, the ISL9120 simplifies design and extends battery life. The wide input and output voltage range provides flexibility to cover a variety of design needs.

To order samples, eval boards or download a datasheet, please visit the ISL9120 product page. Thank you for watching.

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