The ISL9123B is a highly integrated buck-switching regulator capable of supplying output voltage down to 0.4V. The device features an extremely low quiescent current consumption of 950nA in regulation mode, 140nA in forced bypass mode (ISL9123/A), and 7nA in shutdown mode. It provides 86% efficiency at 10μA load (VIN = 3.6V, VOUT = 3.3V) and has peak efficiency greater than 97% (VIN = 3.6V, VOUT = 3.3V) for ISL9123/A. It supports input voltages from 1.8V to 5.5V.

The ISL9123/A device has automatic bypass functionality for situations in which the input voltage is close to or below the output voltage. In addition to the automatic bypass functionality, the forced bypass power-saving mode can be chosen if voltage regulation is not required. Forced bypass power saving mode is accessible using the I2C interface bus.

The device is capable of delivering up to 600mA of output current (VIN > 2.5V) and provides excellent efficiency because of its adaptive frequency hysteretic control architecture.

The device is designed for stand-alone applications and supports a default output voltage at Power-On Reset (POR). After POR, the output voltage can be adjusted in the range of 0.4V to 5.375V for (ISL9123/A) and to 1.180V (for ISL9123B) by using the I2C interface bus. Specific default output voltages are available upon request. The device requires only a single EIA 0603 size inductor and a minimum of two external capacitors. The power supply solution size is minimized by a 1.8mm x 1.0mm 8 Bump WLCSP and is also available in a 3.0mm x 2.0mm 8 Ld plastic DFN.


  • 950nA quiescent current
  • 86% efficiency at 10µA load (VIN = 3.6V, VOUT = 3.3V)
  • 97% peak efficiency (VIN = 3.6V, VOUT = 3.3V) (ISL9123/A)
  • Input voltage range: 1.8V to 5.5V
  • Output voltage range: 0.4V to 5.375V (ISL9123/A)
  • Output voltage range: 0.4V to 1.180V (ISL9123B)
  • Output current: up to 600mA (VIN > 2.5V)
  • Selectable forced and auto bypass power saving modes (ISL9123/A only)
  • PFM and PWM modes with seamless transition
  • I2C control and voltage adjustability
  • Hysteretic controller
  • Auxiliary switched output (ISL9123/A only)
  • Small 1.8mm x 1.0mm 8 Bump WLCSP, and 3.0mm x 2.0mm 8 Ld DFN packages




  • Smart watches and wristband devices
  • Wireless earphones
  • Internet of Things (IoT) devices
  • Water, gas, and oil meters
  • Portable medical devices
  • Hearing aid devices


Type Title Date
Datasheet PDF 1.57 MB
Brochure PDF 5.49 MB 日本語
2 items

Design & Development

Boards & Kits

Boards & Kits