STMicroelectronics A6983 DC/DC converters

STMicroelectronics has launched the A6983 automotive-qualified step-down synchronous DC/DC converters, designed to save space and ease integration in applications including body electronics, audio systems and inverter gate drivers.

The converters offer flexible design choices, comprising six non-isolated step-down converters in low-consumption and low-noise configurations and the A6983I isolated buck converter. With compensation circuitry on-chip, these monolithic devices need only minimal external components including filtering, feedback and a transformer with the A6983I.

The non-isolated A6983 converters can supply up to 3 A load current and achieve 88% typical efficiency at full load. The low-consumption variants (A6983C) are designed for light-load operation, with high efficiency and low output ripple, to reduce drain on the vehicle battery in applications that remain active when parked. The low-noise A6983N variants operate with constant switching frequency and reduce output ripple across the load range for enhanced performance in applications such as audio-system power supplies. Both types offer a choice of 3.3 V, 5.0 V and adjustable output voltage from 0.85 V to VIN.

The A6983I is a 10 W iso-buck converter with primary-side regulation that eliminates the need for an optocoupler. Suitable for use as an isolated gate driver for IGBTs or silicon-carbide (SiC) MOSFETs in traction inverters and onboard chargers (OBCs), this converter enables adjustment of the primary output voltage. The transformer turns ratio determines the secondary voltage.

All isolated and non-isolated variants have a low quiescent operating current of 25 µA and a power-saving shutdown mode that draws less than 2 µA. The input-voltage range from 3.5 to 38 V, and load-dump tolerance up to 40 V, prevent disruption due to transients on the main supply bus. There is also output overvoltage protection, thermal protection and internal soft start. In addition, optional spread-spectrum operation helps lower electromagnetic interference (EMI) for noise-sensitive applications, and a power-good pin enables power sequencing. The A6983I and A6983 allow synchronisation to an external clock.

The converters are offered in a 3 x 3 mm QFN16 package, with free samples of the A6983 and A6983I available from the ST eStore.