MOSFET driver aims for next-generation notebooks

The ISL6208 is a 30V synchronous-buck MOSFET driver IC designed for high-current multiphase power solutions in notebook PCs.

The ISL6208 is a 30V synchronous-buck mosfet driver IC designed for high-current multiphase power solutions in notebook PCs.

The ISL6208 enhanced mosfet driver provides higher efficiency than conventional mosfet drivers by employing a diode emulation mode during light-load conditions, enabling extended battery run time in portable PC applications.

This new driver is offered in a choice of either an 8-lead SOIC or a near-chip-scale 8-pad 3 x 3mm quad flat no-lead (QFN) package that provides flexibility and space savings.

In addition, the ISL6208 integrates a bootstrap diode and eliminates the need for a CPU protection Schottky diode, which reduces external component cost.

"The ISL6208 is a very robust mosfet driver IC that delivers a solid 4A of drive to ensure optimal mosfet switching and power efficiency", said Dean Henderson, Director of Intersil's Notebook Power Products.

"This new IC packs high performance into a very tiny 3 x 3 QFN package, improving thermal and space efficiencies for CPU power regulation solutions in notebook and other portable PCs".

Light-load converter efficiency is enhanced markedly by the ISL6208'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 feature prevents the output from sinking current and avoids the generation of a negative transient, especially significant for power solutions that must power up into prebiased loads.

Two or more ISL6208 drivers combined with one of Intersil's PWM controllers provide a highly efficient multiphase voltage regulator solution with high-frequency switching capability.

The ISL6208 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 mosfet switching, which prevents shoot through and improves conversion efficiency.

Each driver is capable of a 3000pF load with a low propagation delay and a less than 8ns transition time.

The ISL6208 features 4A typical sinking current for the lower gate driver.

This hefty sink current is capable of holding the lower mosfet gate off during the rising edge of the phase node, which prevents shoot-through power loss caused by the high dv/dt rate of phase voltage swing.

The operating voltage matches the 30V breakdown voltage of the mosfets commonly used in mobile computer power supplies.

This advanced mosfet driver 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 bill-of-materials cost versus competitors' drivers.

The ISL6208 is available now.

The suggested resale price for quantities of 100 to 999 units is $1.02 for the ISL6208CB (SOIC package) and $1.06 for the ISL6208CR (QFN package).

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