NATIONAL Semiconductor, represented by Arrow Electronics , has announced an integrated high-voltage cascaded dc-dc controller suitable for power conversion in computer and communications systems.
National has also introduced two 100V power MOSFET drivers that work seamlessly with the new controller, providing customers with a chipset solution for communications power systems, automotive power systems, -48V distributed power systems, motor drive systems, industrial power supplies and half-bridge and full-bridge converters.
The chipset is endorsed by industry leaders such as Magnetek, a major digital power supply manufacturer.
The cascaded buck-fed topology is preferred in applications with a large voltage step-down ratios, the turns ratio of the isolation transformer allows the buck pre-regulator to operate at larger duty cycles, improving efficiency.
National's LM5041-LM5102 chipset simplifies control, drive and regulation in cascaded buck-fed topologies. The LM5102 100V synchronous buck driver drives the step-down converter control and synchronous MOSFETs into the current source inductor [current fed case] or inductor-capacitor filter [voltage-fed case]; this feeds the primary center tap of a push-pull converter isolation transformer.
The LM5041 drives the push-pull MOSFETs directly and the buck pre-regulator indirectly through the LM5102 with a PWM signal from its current-mode controller.
National's new LM5041 is an integrated current-mode pulse width modulated (PWM) controller incorporating a buck pre-regulator controller synchronised to push-pull MOSFET drivers with peak currents of 2A and programmable dead time.
The LM5101 and LM5102 are 100V half-bridge power MOSFET drivers designed to drive both the high side and low side N-Channel MOSFETs in a synchronous buck or a half-bridge configuration.
The LM5101/LM5102 and the LM5041 form a complete chipset solution, providing customers with flexibility to scale power MOSFETs to the power requirements of the dc-dc converter.
A second LM5101 can be applied at the push-pull outputs of the LM5041 for customers preferring cascaded half or full-bridge topologies. The LM5102 also provides programmable rise-time control that allows designers to "tune" the power supply for maximum efficiency and limit EMI.