Synchronous Step-Down Converters with Low Quiescent Current to Simplify Power-Supply Design

Published  April 8, 2021   0
Synchronous Step-Down Converters

Extending the family of high-efficiency converters that simplify power-supply design, STMicroelectronics has introduced integrated 1.5A L6981 synchronous step-down regulators. Simplify high-efficiency power conversion; these regulators deliver 90% typical efficiency at full load.

Available in two variants, the L6981 synchronous step-down converters are optimized for light-load efficiency and noise performance. These devices use pulse skipping for low-current operation and to maximize efficiency at light loads extending the runtime of battery-powered devices. With input voltage from 3.5V to 38V, the L6981N regulators are best suited for 24V industrial bus-powered applications, 12V and 24V battery-powered equipment, HVAC power supplies, decentralized intelligent nodes, smart sensors, and always-on applications. Besides, the output voltage can be adjusted from 0.85V up to the input-voltage value using external resistors.

The regulators prioritize low noise by operating permanently in PWM (pulse-width modulation) mode at the constant switching frequency and minimizing voltage ripple at light loads. These devices come with integrated features like high-side and low-side NMOS power transistors, feedback-loop compensation, over-voltage protection, and thermal protection, soft-start circuitry that limits inrush current and ensures a constant output-voltage slope.

These devices come with an Enable that permits power-up/power-down sequencing and allows a synchronizing clock signal to be applied to the L6981N low-noise converters. As far as the availability is concerned, the L6981 regulators are in production and are available in a proven, rugged SO8L package, from $1.00 for orders over 1000 pieces. The STEVAL-L6981CDR evaluation board for the low-current converter and STEVAL-L6981NDR too are available for the designers to accelerate device selection in power-supply development.