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Intersil Releases Fast Dual Mode MOSFET Driver IC for High-Current Multiphase Power Converters

-- New driver raises the bar on performance by enabling multiphase dc/dc converter

MILPITAS, CA, December 17, 2003 – Intersil Corporation (NASDAQ: ISIL), a world leader in the design and manufacture of high performance analog solutions, today announced a new synchronous-buck MOSFET driver IC designed for high-current multiphase power solutions used in a wide range of datacom, telecom and computing applications where the highest performance-to-price ratio is required. The Endura™ ISL6608 driver IC offers fast switching with up to 4-A drive current for synchronous-buck configured N-channel MOSFETs and is able to switch to a diode-emulation standard-buck mode to smoothly start up into pre-biased loads. In addition, the ISL6608 integrates several monitoring and protection functions in an 8-lead SOIC and a tiny 8-lead 3mm x 3mm QFN package in both commercial and industrial temperature ranges.

“The ISL6608 addresses a host of market applications, such as digital ASICS and FPGAs, where startup into a pre-biased load is required,” said Cindy Drapcho, Vice President of Intersil’s Desktop/File Server Power Products. “These digital circuits are a growing market and require specialized multiphase voltage regulation and power conversion. Intersil, the multiphase PWM controller and FET driver market leader, has moved to address this need with this advanced MOSFET driver and a selection of companion PWM controllers, offering customers the industry’s highest performance-to-price ratio.”

Light-load converter efficiency and pre-biased load startup are enhanced by the ISL6608’s diode emulation feature. When diode emulation is enabled, the driver allows discontinuous conduction by detecting when the inductor current reaches zero and subsequently turns off the low-side MOSFET. This prevents the output from sinking current and avoids the generation of a negative transient.

The ISL6608 enables pre-biased load operation of a multiphase buck converter, and targets a myriad of growing FPGA applications. There are two conditions that lead to a pre-biased load:

• A components I/O voltage, typically 3.3 V, may be up before the CPU or FPGA core voltage and forward biases isolation diodes charging the core voltage supply input capacitors.
• The FPGA may be completely powered down but has voltages on its input pins from other equipment. This voltage forward biases ESD diodes charging the core and I/O supplies input capacitors.

A voltage regulator needs to be able to power up into a pre-biased load by disabling its lower FET while in soft start. In this condition, the synchronous multiphase buck converter acts as a standard buck converter.

Two or more of these drivers plus an Intersil HIP63xx or ISL65xx multiphase PWM controller form a multiphase voltage regulator solution with high-frequency switching capability. The ISL6608 is biased by a single 5-V supply and minimizes high-side driver switching losses in high gate capacitance and high switching frequency applications. Each driver is capable of a 3000-pF load with a low propagation delay and a less than 10-ns transition time.

The ISL6608 includes an internal charge pump utilizing a Schottky bootstrap diode which enables the use of N-channel MOSFETs and reduces implementation cost and complexity. The driver provides adaptive shoot-through protection to prevent simultaneous conduction of both MOSFETs. High drive capability ensures crisp FET switching, which prevents shoot through and improves conversion efficiency.

The ISL6608 also features a three-state PWM input that, working together with Intersil’s multiphase PWM controllers, will prevent a negative transient on the output voltage when the output is being shut down. This feature eliminates the Schottky diode that is typically used in a microprocessor power system to protect the microprocessor from reversed-output-voltage damage, further reducing the BOM cost versus competitors’ drivers.

ISL6608 Technical Summary

• Diode emulation mode improves performance for light-load and pre-biased load operation
• Drives two N-channel MOSFETs for higher performance and lower cost
• Adaptive shoot-through protection reduces power loss and ensures reliability
• 4-A current sink capability for solid control
• High-frequency switching to 2 MHz reduces component size and cost
• Three-state PWM input prevents output shut-down transient
• Internal bootstrap Schottky diode saves space, complexity, cost
• Low IC bias current of only 80 uA reduces power budget
• Integrated Vcc power-on-reset feature reduces complexity and cost
• Pin compatible with Intersil’s popular ISL6605 MOSFET driver IC
• 3 X 3 mm, 8-pad, QFN package for enhanced thermal performance and space savings
• 8-lead SOIC package option
• Commercial (0 to 70 deg. C) and industrial (-40 to +85 deg. C) temperature ranges

ISL6608 Pricing and Availability
The ISL6608 is available now in choice of package and temperature range. The suggested resale price in 10,000 unit quantities is $0.99 for each IC. ICs are available on tape and reel. About Intersil
Intersil Corporation is a leader in the design and manufacture of high performance analog semiconductors. The company’s products address three of the industry’s fastest growing markets - flat panel displays, optical storage (CD and DVD recordable) and power management. Intersil products include power management devices for battery management, hot-swap and hot-plug controllers, linear regulators, supervisory ICs, switching DC-DC regulators and power MOSFET drivers; optical storage laser diode drivers; DSL line drivers; video and high performance operational amplifiers; data converters; interface ICs; analog switches and multiplexers; crosspoint switches; voice-over-IP devices; and ICs for military, space and rad-hard applications. For more information about Intersil or to find out how to become a member of our winning team, visit the company’s web site and career page at: www.intersil.com.

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