ST introduces isolated buck converters that reduce bill of Material costs for automotive and industrial applications

     Designed for isolated step-down regulators, ST's A6986I and L6986I DC/DC converter chips have optimized product characteristics with a wide input voltage range and low static current, ensuring stable and efficient operation of the converter in automotive and industrial applications with a maximum output power of 5W.

     If a system requires a non-isolated primary side regulator and one or more isolated secondary side regulators, isolated step-down topologies can significantly reduce the bill of materials cost of the system. The secondary side voltage is determined by the turn ratio of the transformer coil, and the voltage regulating circuit does not need an optical coupler. Common applications include power supply for SiC MOSFET and IGBT transistor gate drivers requiring asymmetrically isolated power rails and isolated interfaces RS-232, I2C, SPI, etc.

     A6986I is AEC-Q100 Grade-1 certified and typical applications include on-board charger (OBC) and hybrid/electric vehicle (H/EV) power motor drivers. Up to 100% duty cycle and 4V-38V wide input voltage comply with technical specifications for cold start and load dumping of automotive systems. The industrial-grade L6986I is ideal for motor drives, solar conditioning systems, uninterruptible power supplies (UPS) and welders.

     Both converters use a forced PWM mode and have a peak current mode control function to adjust the primary output voltage. The extended range of negative current limits on the primary side provides more flexibility, and the appropriate secondary current can be obtained using a typical transformer coil turn ratio. The soft start of the converter can be set, which can work reliably, and also provides pulse current detection function for the constant current protection of the primary side. The 300ns preset current detection blanking time can filter the oscillation caused by the transformer leakage induction, ensuring that the chip has higher stability during the on-off of the high side switch. The chip has built-in overvoltage protection and thermal shutdown protection, and external clock synchronization and switching frequency setting pins.

     Evaluation boards for both converters help speed up the development cycle of single - and dual-output gauge converters. STEVAL-A6986IV1 has 18V and -4.5V dual voltage isolated output; The STEVAL-A6986IV2 has a 5V single voltage isolated output. Users can adjust the output voltage with external devices.