Multiphase controller offers current-sense options

The Endura ISL6561 is a precision two- to four-phase PWM controller IC for new VRM10-based platforms.

The Endura ISL6561 is a precision two- to four-phase PWM controller IC for new VRM10-based platforms.

The ISL6561 IC is the world's first PWM controller to offer designers a choice of either lower mosfet on resistance or output inductor DCR (DC resistance) current-sensing topologies.

This advanced controller is supplied in the space-saving and thermally efficient 40-pad 6 x 6mm QFN package.

It is designed for new VRM10 desktop, workstation, and server designs where reliability, and precision performance are critical.

"Combined with our QFN packaged mosfet drivers, the ISL6561 precision controller provides VRM10 platform designers with everything they need to meet stringent performance, space and cost requirements", said Cindy Drapcho, Director of Intersil's Desktop Power Products.

"The ISL6561 meets all VRM10 specifications and gives designers the freedom of choice for either of the popular current-sensing techniques".

Today's microprocessors require a tightly regulated output voltage position versus load current (droop).

This CPU core voltage prepositioning enables the DC/DC convertor to maintain its regulation during severe load transients without the addition of energy-storing output capacitors.

The ISL6561 senses the output current by using patented techniques to measure the voltage across the on resistance of the lower mosfets or DCR of the output inductor during their conduction intervals.

Current sensing provides the needed signals for precision droop, channel-current balancing and over current protection.

The accuracy of the on-resistance current-sensing method is enhanced by the ISL6561's integrated temperature compensation function.

Droop accuracy, phase current balance and overcurrent protection can be affected by temperature related changes in on resistance or DCR.

The ISL6561 uses an internal temperature-sensing element to provide programmable temperature compensation.

This eliminates the need for an external thermistor.

Correctly applied, temperature compensation can completely nullify the effect of on resistance or inductor DCR temperature sensitivity.

A unity-gain differential amplifier is provided for remote voltage sensing.

Any potential difference between remote and local grounds can be eliminated using the remote-sense amplifier.

Eliminating ground differences improves regulation and protection accuracy.

The threshold-sensitive enable input is available to accurately coordinate the startup of the ISL6561 with Intersil's external mosfet drivers.

Dynamic VIDT technology allows seamless on-the-fly VID (voltage identification number) changes.

The offset pin allows accurate voltage offset settings that are independent of the VID setting.

The ISL6561 has a built-in shunt regulator to allow 12V-only bias using a small external limiting resistor.

Differential current sensing further enhances current sensing accuracy because any errors introduced by an asymmetrical multiphase layout are offset.

The ISL6561 is a precise multiphase PWM controller providing 0.5% system accuracy over load, line and temperature.

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