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Intersil Introduces New Single-Phase Dual-Mode PWM Controller IC with Integrated MOSFET Drivers

-- Enables low-cost, small-footprint POL supplies with dual-mode soft-start capability~-- Solves startup problems associated with pre-biased loads as often exist with FPGAs and ASICs

MILPITAS, CA, April 5, 2004 – Intersil Corporation (NASDAQ: ISIL), a world leader in the design and manufacture of high performance analog solutions, today announced the new Endura™ ISL6522B single-phase dual-mode synchronous-buck PWM controller/driver IC designed to provide exceptional soft-start to power sensitive circuits and gracefully handle pre-biased loads. The ISL6522B integrates two MOSFET drivers and has the ability to soft-start in a standard-buck mode and seamlessly switch to the synchronous-buck mode. Applications for this new IC include, but are not limited to, powering microprocessors, FPGAs and ASICs, memory, chip sets as point-of-load (POL) modules or embedded supplies. The high degree of component and function integration makes this IC a high-performance and cost-saving alternative to legacy solutions.

“Like our recently announced ISL6608 dual-mode MOSFET driver, the ISL6522B single-phase dual-mode PWM controller with integrated drivers is designed to meet the emerging needs of the rapidly expanding FPGA and ASIC markets,” said Cindy Drapcho, Vice President of Intersil’s Power Products. “Often, FPGAs or ASIC cores exist in a pre-biased condition because of alternate voltage paths, usually from I/O supplies. Pre-biasing can cause an initial undesirable voltage swing if the regulator is not designed to handle such loads. The ISL6522B’s standard-buck soft-start mode overcomes the pre-bias condition and provides smooth regulation startup. Problem solved. That’s what we do.”

The ISL6522B provides complete control and protection and is optimized for high-performance POL applications. It is designed to drive two N-Channel MOSFETs in a synchronous rectified buck topology and has standard-buck soft-start capability. The ISL6522B integrates all of the control, output adjustment, monitoring and protection functions into one space and cost-saving package.

The ISL6522B enables pre-biased load operation and targets a myriad of growing FPGA applications. There are two common scenarios that lead to a pre-biased condition:

• A components I/O voltage, typically 3.3 V, may be up before the CPU or FPGA core voltage, which 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 ISL6522B acts as a standard buck converter.

The output voltage of the ISL6522B converter can be precisely regulated to as low as 0.8 V, with a maximum tolerance of +/-1% over temperature and line voltage variations. The ISL6522B provides simple, single feedback loop, voltage-mode control with fast transient response. It includes a 200-kHz free-running triangle-wave oscillator that is adjustable from below 50 kHz to over 1 MHz. The error amplifier features a 15-MHz gain-bandwidth product and 6-V/us slew rate which enables high converter bandwidth for fast transient performance. The resulting PWM duty ratio ranges from 0 to 100%.

The ISL6522B protects against over-current conditions by inhibiting PWM operation. Current is monitored using the RDS(ON) of the upper MOSFET which eliminates the need for a current sensing resistor.

ISL6522B Technical Summary

• Dual-mode PWM controller with integrated MOSFET drivers
  • Drives two N-channel MOSFETs
  • Standard-buck soft start with seamless switching to synchronous mode
• +5 V or +12 V input
• Simple single-loop voltage-mode PWM control
• Fast transient response
  • High-bandwidth error amplifier
  • Full 0–100% duty ratio
• 0.8 V internal reference
• +/-1% accuracy over line voltage and temperature
• Over-current fault monitor
• MOSFET RDS(ON) current sensing
• Converter can source and sink current
• 200-kHz free-running oscillator programmable from 50 kHz to over 1 MHz
• 14-lead SOIC and TSSOP packages
• Space-saving and thermally enhanced 16-pad 5 X 5 mm QFN package

ISL6522B Pricing and Availability
The ISL6522B is available now. The suggested resale price in 100 to 999-unit quantities is as follows:

ISL6522BCB	0 to +70 deg.	14-ld SOIC	$1.37
ISL6522BIB	-40 to +85 deg.	14-ld SOIC	$1.47
ISL6522BCV	0 to +70 deg.	14-ld TSSOP	$1.45
ISL6522BIV	-40 to +85 deg.	14-ld TSSOP	$1.52
ISL6522BCR	0 to +70 deg.	16-pad 5X5mm QFN	$1.63
ISL6522BIR	-40 to +85 deg.	16-pad 5X5mm QFN	$1.63

ICs are available on tape and reel.

Additional information on these and other high-performance power solutions can be obtained online from Intersil’s Power Web site at: http://www.intersil.com/power/ About Intersil
Intersil Corporation, a NASDAQ 100 Index company, 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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