Renesas regulator reduces power for IoT devices

  • October 21, 2020
  • Steve Rogerson

Japanese semiconductor company Renesas has introduced a buck-boost switching regulator with bypass mode that provides low quiescent current to power sensors, microcontrollers, wireless devices and other IoT components.

Operating with battery output from 1.8 to 5.5V, the ISL9122A extends the battery life of smart IoT devices powered by coin-cell, lithium and multiple series alkaline batteries. Target applications include wireless earbuds, fitness bands, smart watches, water and gas meters, portable medical devices, and other battery-operated smart IoT devices.

The regulator implements dynamic voltage scaling in I2C programmable 25mV steps to optimise system power consumption. The regulator’s power boost up to 5.375V increases RF capabilities of IoT devices across their battery range. Its PFM and PWM functionality boosts efficiency over the whole output current range. In forced PWM mode, the regulator always switches at 2.5MHz, which improves EMI performance.

“With the explosive growth of IoT wireless connectivity applications, the ISL9122A buck-boost regulator’s fast transitions from no load to full load is ideal for powering the newest generation of devices,” said Andrew Cowell, vice president at Renesas. “Our customers praise the ISL9122A’s flexibility, dynamic voltage scaling and lowest regulated standby power consumption.”

The regulator joins the recently released ISL9123 buck regulator. Both can power the firm’s RL78 family of 8 and 16bit low-energy MCUs, RA family of 32bit MCUs with Arm Cortex-M core, and the RE family of embedded controllers for wearables and energy harvesting applications.

Quiescent current is less than 1.3µA and shutdown mode current is 7nA to extend battery life. Efficiency at light load is 84% at 10µA and peak efficiency is 97% to reduce power drain and heat build up.

The automatic and selectable forced bypass power saving mode reduces quiescent current.

There is an adjustable output voltage range from 1.8 to 5.375V in 25mV increments. Maximum output current is up to 500mA with Vout at 3.3V and Vin at 3.6V.

Devices come in either a 1.8 by 1.0mm WLCSP or 3 by 2mm DFN package. They only require three external components: one inductor, and input and output capacitors. There is protection against overcurrent, short-circuit and overheating.

The ISL9122A is available now from distributors and is priced at $0.89 (eight-lead DFN package) and $0.78 (eight-bump WLCSP package) each in 1000-unit quantities.

Two ISL9122A evaluation boards allow designers to evaluate device features and performance. Both have 3.3V default output. The ISL9122AIRN-EVZ (DFN) and ISL9122AIIN-EVZ (WLCSP) are both priced at $70.