1.5A dc-dc buck works from 3.5 to 38V

1.5A dc-dc buck works from 3.5 to 38V

Called L6981, it works from inputs across 3.5V to 38V, and across -40 to 125°C, suiting the converter to industrial applications.

Using a pair of resistors, output voltage can be adjusted from 85omV up to the input-voltage.

There are two variants:

  • L6981CDR  – set to pulse-skipping ‘low consumption’ mode
  • L6981NDR – set to fixed frequency PWM ‘low noise’ mode, can be synchronised

Shutdown current for either is 3μA max. Quiescent is typically 35μA (60μA max) for the pulse skipper and 2.3mA (3mA max) for the PWM version.

Integrated features include high-side and low-side n-channel Power transistors (with bootstrapping to drive the upper device), feedback-loop compensation, over-voltage protection and thermal protection. Soft-start circuitry limits inrush current and ensures a constant output-voltage slope.

An Enable pin permits power-up and power-down sequencing, and is how the synchronising clock can be applied to fixed frequency versions.

Packaging is SO8L, and L6981 is included in ST’s 10-year longevity programme.

Evaluation boards are STEVAL-L6981CDR for the low-consumption version and STEVAL-L6981NDR for the low-noise version.

Applications are foreseen in 24V industrial bus-powered applications, 12V and 24V battery-powered equipment, air conditioning power supplies, decentralised intelligent nodes and smart sensors.

The L6981 product page is here