STMicroelectronics L6983/L6983I Synchronous Step-Down Converter

The L6983 is available both in low consumption mode (LCM) and low noise mode (LNM) versions. LCM maximizes the efficiency at light-load with controlled output voltage ripple so the device is suitable for battery-powered applications. LNM makes the switching frequency constant and minimizes the output voltage ripple for light load operations, meeting the specification for low noise-sensitive applications. The L6983 allows the switching frequency to be selected in the 200kHz to 2.2MHz range with an optional spread spectrum for improved EMC.

The EN pin provides an enable/disable function. The typical shutdown current is 2µA when disabled. As soon as the EN pin is pulled up, the device is enabled, and the internal 1.3ms soft-start takes place. The L6983 features Power Good open collector that monitors the FB voltage. Pulse-by-pulse current sensing on both power elements implements an effective constant current protection, and thermal shutdown prevents thermal run-away.

The STMicroelectronics L6983 Synchronous Step-Down Converter is offered in a 3mm x 3mm QFN-16 package with internal compensation, thus minimizing design complexity and size.

L6983I 38V, 10W Synchronous Iso-Buck Converter for isolated applications is designed explicitly for isolated buck topology. The primary output voltage of L683I can be accurately adjusted, whereas the isolated secondary output is derived using a given transformer ratio. No optocoupler is required. The primary sink capability up to -4.5A (even during soft-start) allows a proper energy transfer to the secondary side as well as enabling a tracked soft-start of the secondary output.

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