The ISL91108 is a highly-integrated buck-boost switching regulator that accepts input voltages either above or below the regulated output voltage. Unlike other buck-boost regulators, this regulator automatically transitions between operating modes without significant output disturbance.

This device is capable of delivering up to 2.7A of burst current (PVIN = 3V, VOUT = 3.3V), and provides excellent efficiency due to its fully synchronous 4-switch architecture. No load quiescent current of only 27.5µA also optimizes efficiency under light-load conditions. Forced PWM and/or synchronization to an external clock may also be selected for noise sensitive applications.

The ISL91108 is designed for standalone applications and supports a 3.3V fixed output voltage or variable output voltages with an external resistor divider. Output voltages as low as 1V or as high as 5.2V are supported using an external resistor divider.

The ISL91108 requires only a single inductor and very few external components. Power supply solution size is minimized by a 2.34mm x 1.72mm WLCSP and a 2.6MHz switching frequency, which further reduces the size of external components.


  • Accepts input voltages above or below regulated output voltage
  • Automatic and seamless transitions between buck and boost modes
  • Input voltage range: 1.8V to 5.5V
  • Output current: up to 1.6A DC (PVIN = 2.8V, VOUT = 3.3V)
  • Burst current: up to 2.7A (PVIN = 3V, VOUT = 3.3V, tON<600µs, t = 4.6ms)
  • High efficiency: up to 95%
  • 27.5µA quiescent current maximizes light load efficiency
  • 2.6MHz switching frequency minimizes external component size
  • Selectable forced PWM mode and external synchronization
  • Fully protected for short-circuit, over-temperature, and undervoltage
  • Small 2.34mm x 1.72mm WLCSP


  • Smartphones and tablets
  • Wireless communication devices
  • 2G/3G/4G power amplifiers


Title language Type Format File Size Date
Datasheets & Errata
star ISL91108 Datasheet Datasheet PDF 627 KB
Application Notes & White Papers
Five Easy Steps to Create a Multi-Load Power Solution White Paper PDF 846 KB
AN9208: High Frequency Power Converters Application Note PDF 592 KB
AN1681: Grounding Techniques Application Note PDF 509 KB
AN1684: Nonideality of Ground Application Note PDF 397 KB
PCN19007A - Carrier Tape change for Renesas Product ISL91108* WLCSP Packaged Product Product Change Notice PDF 182 KB
ISL91108 iSim:PE Model Schematic SXSCH 214 KB

select_allSoftware & Tool Pages

Title Type Description Company
iSim:PE Offline Simulation Tool Simulator iSim Personal Edition (iSim:PE) speeds the design cycle and reduces risk early in any project, identifying parts that can be used in current as well as next-generation designs. Renesas

memoryBoards & Kits

Part Number Title Type Company
ISL91108IIA-EVZ Highly-Integrated Buck-Boost Switching Regulator Evaluation Board Evaluation Renesas
ISL91108IIN-EVZ Highly-Integrated Buck-Boost Switching Regulator Evaluation Board Evaluation Renesas