Milpitas, Calif. - Intersil's new ISL6608, for driving two n-channel power MOSFETs in synchronous-buck, multiphase power converters, features a diode-emulation mode that eases power-up into a pre-biased load and maximizes performance under light-load conditions. "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 for desktop/file server power products. "These digital circuits are a growing market and require specialized multiphase voltage regulation and power conversion. We've 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." The ISL6608 works from a single 5-volt supply. Each driver is capable of handling a 3000-pF load. Propagation delay is low and transition time is less than 10 ns. Two or more of these drivers plus the company's HIP63xx or ISL65xx multiphase PWM controller form a multiphase voltage regulator solution with high-frequency (2 MHz) switching capability.
The chip handles pre-biased loads (due to I/O voltages present before the CPU or FPGA core voltage can be established, or an FPGA that has voltage on its input pins from other equipment) with so-called diode emulation. This circuitry allows the chip to detect when the converter's inductor current reaches zero and subsequently turn off the low-side MOSFET. As a result, it prevents the output from sinking current and generating negative transients. In this mode, the synchronous multiphase buck converter will operate as a standard buck converter. The driver provides adaptive shoot-through protection, aided by the device's 4-amp sink current capability for the lower gate driver, to prevent simultaneous conduction of both MOSFETs.
The ISL6608 also features a three-state PWM input that, working together with the company's multiphase PWM controllers, prevents negative transients when the output stage is being shut down. This feature eliminates the Schottky diode that is typically used in a microprocessor's power system to protect the microprocessor from reversed-output-voltage damage.
The ISL6608, available in a 3-by-3 mm QFN package for the 0 to +70°C commercial and -40 to +85°C industrial temperature range, is priced at 99 cents each in 10K quantities. The ICs are available in tape and reel.