Integration Optimizes Power Conversion Efficiency, Enabling Tiny Footprint and Cost-effective Design Flexibility
February 3, 2003 - Demonstrating its leading position in power management innovations, National Semiconductor (NYSE: NSM) announced today an integrated high-voltage Cascaded dc-dc controller ideal for power conversion in computer and communications systems. National also introduced two 100 V power MOSFET drivers that work seamlessly with the new controller, providing customers with a chipset solution for communications power systems, automotive power systems, -48 V distributed power systems, motor drive systems, industrial power supplies and Half-Bridge and Full-Bridge converters.
"The Cascaded controller-driver chipset puts National Semiconductor in the forefront of the high-voltage power IC market," said Paul Greenland, Marketing Director for the power management product line at National Semiconductor. "Offering customers a unique combination of strong design capability, manufacturing strength and innovative packaging, National is the only company that provides such a high level of integration in the smallest package."
The evaluation board for the chipset will be on display at the Applied Power Electronics Conference and Exposition (APEC) 2003, Feb. 9-13, at the Fontainebleau Hotel in Miami Beach, FL. The chipset is endorsed by industry leaders such as Magnetek, a major digital power supply manufacturer. "Magnetek chose National Semiconductor because of their innovative solution," said Lorenzo Cincinelli, CTO at Magnetek in Italy. "The high integration level of National's high-voltage devices will allow us to produce telecom power supply modules with outstanding performances and reliability levels."
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 100 V 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 synchronized to Push-Pull MOSFET drivers with peak currents of 2A and programmable dead time. A high-speed controller with a user-programmable 1 MHz oscillator, external clock synchronization capability and current limit propagation delay of less than 100 ns, the LM5041 integrates on to a single die unique features such as:
- Fully Integrated Synchronous Buck Control and Push-Pull Drivers with programmable dead time.
- Wide range, 15 V-to-100 V start-up bias regulator
- High-speed, 2 A peak Push-Pull MOSFET drivers
- User-programmable soft-start circuitry
- Tiny, thermally enhanced, 16-pin leadless lead frame package (LLP-16, 5 mm X 5 mm)
- Cascaded controller mates with 100 V Synchronous-Buck driver(s) (LM5101 and LM5102)
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Allows flexible configurations: interleaved forward, Cascaded Push-Pull, Half or Full-Bridge
The LM5101 and LM5102 are 100 V 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.
The LM5101 and LM5102 feature:
- 100 V Synchronous-Buck driver which mates with the LM5041 100 V Cascaded controller
- User-programmable turn-ON edge delay feature on the LM5102 driver
- Tiny, thermally enhanced 10-pin leadless lead frame package (LLP-10, 4 mm X 4 mm)
Availability, Pricing and Packaging
National Semiconductor's LM5041 Cascaded controller in a LLP-16 package is priced at $2.55 each in 1,000 quantities. The LM5101 and LM5102, both in a LLP-10 package, are priced at $1.75 each and $1.79 each in 1,000 quantities, respectively. The LM5041 and LM5100's will be available for sampling in April with volume production in June and September, respectively.
