L6718 datasheet(26/71 Pages) STMICROELECTRONICS

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Device description and operation

L6718

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DocID023399 Rev 3

Device description and operation

The L6718 dual output PWM controller provides an optimized solution for Intel VR12 CPUs

and DDR memory. The three embedded high-current drivers guarantee high performance in

a very compact motherboard design. Both sections feature a differential voltage sensing

and provide complete control logic and protection for high performance stepdown DC-DC

voltage regulators. The multi-phase rail is designed for Intel VR12 CORE or DDR section

and features from 2 to 4 phases. The single-phase rail is designed for the GPU section or

VTT, or as independent DC-DC voltage regulator.

The multi-phase buck converter is the simplest and most cost-effective topology employable

in order to satisfy the high-current requirements of the new microprocessors and modern

high-current VRMs. It allows distribution of equal load and power between the phases using

smaller and cheaper, and more common, external Power MOSFETs and inductors.

The device features 2nd generation LTB Technology™: through a load transient detector, it is

able to turn on simultaneously all the phases. This allows the minimization of the output

voltage deviation and the system cost by providing the fastest response to a load transient.

The device features an additional power management interface compliant with SMBus 2.0

specifications. This feature increases the system application flexibility; the main voltage

regulation parameter (such as overclocking) can be modified while the application is

running, assuring fast and reliable transition.

The device can be run also as a DDR supply which uses the single-phase for the

termination voltage.

The L6718 is designed to run with 2 embedded drivers for the multi-phase rail and one for

the single-phase rail. By using the SWAP mode, it is possible to move all 3 embedded

drivers for the multi-phase rail while the single-phase rail is controlled by an external PWM.

Single-phase rail can also be turned off.

The device supports Jmode; with this feature the single-phase rail becomes an independent

rail with an external enable and VREADY.

The L6718 implements current reading across the inductor in fully differential mode. A

sense resistor in series to the inductor can also be considered to improve reading precision.

The current information read corrects the PWM output in order to equalize the average

current carried by each phase of the multi-phase rail section.

The controller supports VR12 specifications featuring a 25-MHz SVI bus and all the required

registers. The platform can program the default registers through dedicated pinstrapping.

A complete set of protections is available: overvoltage, undervoltage, overcurrent (per-

phase and total) and feedback disconnection guarantees the load to be safe for both rails

under all circumstances.

Special power management features like DPM and VFDE modify the phase number, and

switching frequency to optimize the efficiency over the load range.

The L6718 is available in VFQFPN56 with 7x7 mm body package.

L6718 Datasheet(PDF) 26 Page - STMicroelectronics

L6718 Datasheet(HTML) 26 Page - STMicroelectronics

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