PWM Controller – advances power conversion performance

Intersil released the ISL6744 , an industry-leading double-ended controller intended for unregulated bus converters in 48-V DC-DC and off-line AC-DC power supplies. The ISL6744 delivers economy, flexibility, simplicity and industry-leading performance that places it at the top of the list for power supply designers.

The controller works over a wide range of input voltages bringing high performance and cost savings to isolated-bus applications including 400V power-factor-corrected AC/DC converters and 48V intermediate buses for telecom, datacom, and server systems. The intermediate bus architecture (IBA) provides voltage step-down conversion and high-voltage isolation to service many non-isolated point of load (POL) DC-to-DC converters.

In a typical 48V IBA, the ISL6744 is used to translate the 48V bus voltage down to a lower unregulated intermediate bus voltage, usually in the range of 8 to 16V. This conversion circuit also provides electrical isolation, isolating the lower voltage bus from the 48V bus in the event of catastrophic component failure. Non-isolated POL DC-to-DC converters then tap off of this low-voltage intermediate bus to provide even lower voltages directly at the distributed loads.

In this way, the IB architecture minimizes wide-area distribution losses at the 48-V level, provides isolation for the intermediate levels and allows for the use of efficient and economical non-isolated POL regulators. Keeping in mind that each level of conversion in an IBA or distributed architecture contributes to a cumulative reduction in system power conversion efficiency, all converters must have the highest possible efficiency.

The ISL6744 has been designed to provide efficiency optimization with its ability to accurately program the output drive signals non-overlap time with delays as fast as 20 ns – five to ten times faster than competing products. This performance allows power engineers to optimize the efficiency of their power modules and achieve conversion efficiencies greater than 95%.

In addition to high conversion efficiency, the ISL6744 provides an adjustable oscillator frequency, adjustable soft start, over-current shutdown, and precise control of the switching frequency. It features low start-up and operating currents, operation up to 1 MHz, integrated 20 V, 1 A MOSFET drivers, and very fast propagation delays, all in a tiny 8-lead MSOP or SOIC package.

For 48-V-input applications, the ISL6744 can be used to control the Intersil ISL6700 or HIP2100 MOSFET drivers to provide an efficient, robust and cost-effective solution. The ISL6744 is also designed to allow easy interfacing with low-cost gate drive transformers in AC-DC bus converter applications.

Intersil Corp , Camberley, Surrey GU15 3YQ, UK.

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