STMicroelectronics Single-chip synchronous buck converter for light load, low noise electrical isolation power applications

     STMicroelectronics has introduced a new family of auto-grade step-down synchronous DC/DC converters that help save board space and simplify the design of applications such as body electronics, audio systems and inverter gate drivers.

     The A6983 converter provides designers with a flexible product selection with six low-power, low-noise non-isolated buck converters and one isolated buck converter, the A6983I. These highly integrated monolithic regulators have built-in compensation circuits that require few external components in practical applications, including filters and feedback devices, and a transformer when developing applications with the A6983I.

     The A6983 non-isolated converter can output up to 3A load current with a typical energy efficiency of 88% at full load. Optimized for light load conditions, the A6983C Low Power converter features high energy efficiency and low output ripple, minimizing the amount of power consumed by the vehicle battery while the vehicle system is still running after parking. The A6983N is a low-noise converter with a constant switching frequency that minimizes the output ripple of the converter over the entire load range and improves performance for applications such as the power supply for automotive audio systems. Both products offer 3.3V, 5.0V and 0.85V to VIN adjustable output voltages.

     The A6983I is a 10W isolated step-down converter with primary side voltage regulation and is designed without optical couplers, making it ideal for use as an isolated gate driver for IGBT or silicon carbide (SiC) MOSFETs in electric drive inverters and on-board chargers (OBCs) to precisely regulate the primary side output voltage. The output voltage of the secondary side is determined by the ratio of turns of the transformer.

     For both isolated and non-isolated products, the static operating current is 25μA, and the power-saving turn-off mode current is less than 2μA. Input voltage range 3.5V to 38V, load drop tolerance up to 40V, prevents transient interruption of the system on the main power bus. The new product also has output overvoltage protection, overheat protection and internal soft start functions. In addition, an optional spread spectrum operation mode helps reduce electromagnetic interference (EMI) for noise-sensitive applications, and power normal pins enable power ordering. The A6983I and A6983 support chip synchronization with the external clock.

     The new series of converters comes in a 3mm x 3mm QFN16 package. Samples of the A6983 and A6983I can be requested free of charge from ST eStore. The evaluation board STEVAL-A6983CV1 and STEVAL-A6983NV1 A6983, as well as the evaluation board STEVAL-L6983IV for A6983I, can help customers quickly start projects and speed up project development.