Synchronous buck at 1.5 A — what the ratings mean for your rail
The L6981C33DR is a 1.5 A, 3.3 V fixed-output step-down converter from STMicroelectronics, switching at 400 kHz with an integrated synchronous rectifier. The 3.5 V to 38 V input range lets it run off a wide variety of unregulated rails — 12 V industrial bus, 24 V automation supply, or a 5 V pre-regulator — without a separate linear pre-drop. The synchronous rectifier eliminates the external freewheeling Schottky diode, saving one component and one placement site per design. At 1.5 A and 400 kHz, the internal low-side FET carries the inductor current during the off-time, so the efficiency curve stays above 85% across most of the load range in typical 12 V-to-3.3 V conversion. Junction temperature is rated from -40°C to 150°C — the same thermal grade as automotive-qualified parts in the family. For a 1.5 A load at 85°C ambient, the junction stays under 125°C with reasonable copper area on the 8-SOIC footprint.
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Sourced through independent distribution channels; availability and current pricing are confirmed at the time of RFQ. No minimum order quantity or lead-time guarantee is stated here — quote against your BOM quantity.