Buck-boost DC/DC converter extends battery life for wireless devices

Renesas Electronics Corp. has released the ISL9122A buck-boost DC/DC converter, targeting applications such as wireless earbuds, fitness bands, smart watches, water and gas meters, portable medical devices, and a range of battery-operated smart IoT devices. This buck-boost switching regulator features a bypass mode that provides ultra-low quiescent current (IQ) for powering sensors, microcontrollers (MCUs), wireless devices, and other system components.

The ISL9122A, operating with a battery output from 1.8 V to 5.5 V, extends the battery life of smart IoT devices powered by coin-cell, lithium, and multiple series of alkaline batteries. The device implements dynamic voltage scaling (DVS) in I2C programmable 25-mV steps to optimize system power consumption, said Renesas.

In addition, the regulator’s power boost up to 5.375 V  maximizes RF capabilities of IoT devices across their battery range. The PFM and PWM functionality maximizes efficiency over the entire output current range, and in forced PWM mode, the regulator always switches at 2.5-MHz frequency, which improves electromagnetic interference (EMI) performance of the system, said the company.

Key features include an ultra-low IQ of <1.3 µA and low shutdown mode current of 7 nA to extend battery life, as well as high efficiency at light load (84% @ 10 µA) and 97% peak efficiency to reduce power drain and heat buildup. Other features include automatic and selectable forced bypass power-saving mode, which reduces IQ, a wide adjustable output range from 1.8 V to 5.375 V in 25-mV increments, a wide input voltage range of 1.8 V to 5.5 V for multiple battery topologies, and a max output current up to 500 mA (Vout = 3.3 V, Vin = 3.6 V).

The ISL9122A is housed in an ultra-small footprint (1.8 x 1.0 mm WLCSP package or 3 x 2-mm DFN package) to save board space. The device only requires three external components: one inductor, and input and output capacitors. It provides full protection against overcurrent, short-circuit, and overheating.

The ISL9122A is available from Renesas’ worldwide distributors and is priced at $0.89 (8-lead DFN package) and $0.78 (8-bump WLCSP package) each in quantities of 1,000. Two ISL9122A evaluation boards are also available: The ISL9122AIRN-EVZ with a 3.3-V default output (DFN) and the ISL9122AIIN-EVZ with a 3.3-V default output (WLCSP). Both are priced at $70.

The ISL9122A buck-boost regulator joins the recently released ISL9123 buck regulator. Both ultra-low IQ switching regulators can power Renesas’ RL78 Family of 8/16-bit ultra-low energy MCUs, RA Family of 32-bit MCUs with Arm Cortex-M Core, and the RE Family of embedded controllers for wearables and energy harvesting applications. The newest member of the RE01 Group family is a 256-KB flash memory variant ultra-low-power MCU.