STMicroelectronics Introduces Highly Integrated 1.5A Synchronous Zener to Simplify High-Efficiency Power Conversion Designs

     STMicroelectronics expands its family of high-efficiency power converters with the introduction of the L6981 synchronous buck regulator, which simplifies power supply design by monolithically integrating power components, feedback circuits and safety functions. The L6981 converter has a rated maximum output current of 1.5A and a typical conversion energy efficiency of 90% at full load. There are two models to choose from, which are optimized for light-load energy efficiency and noise performance.

     The L6981C is geared towards low-current applications and uses a pulse-skipping mode to maximize light-load conversion energy efficiency and extend battery-operated device life, while the L6981N focuses on optimizing light-load noise performance, using a permanent PWM (pulse width modulation) mode and constant switching frequency to minimize light load voltage ripple.

     Both products are compatible with 3.5V-38V input voltage and are suitable for 24V industrial DC bus power, 12V and 24V battery powered equipment, HVAC air conditioner power supplies, distributed smart nodes, smart sensors and always-on applications. By using an external resistor, the output voltage is adjustable from 0.85V to the input voltage value.

     Features integrated on-chip include high- and low-side NMOS power transistors, feedback loop compensation, overvoltage protection, thermal protection, as well as soft-start circuitry and enable pins. Among them, the soft-start circuit can limit the inrush current and ensure a constant rate of rise of the output voltage; the enable pin allows power-up/power-down sequencing and allows a synchronous clock signal to be applied to the L6981N low-noise converter. The L6981 is included in ST's 10-year product life plan with a long-term commitment.

     The STEVAL-L6981CDR low-current converter evaluation board and the STEVAL-L6981NDR low-noise converter evaluation board help power supply designers speed up device selection.