L6759D datasheet(20/51 Pages) STMICROELECTRONICS

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Device description and operation

L6759D

20/51

Doc ID 023240 Rev 1

Device description and operation

The L6759D is a programmable 2/3-phase PWM controller that provides complete control

logic and protection to realize a high performance step-down DC-DC voltage regulator

optimized for advanced DDR memory power supply. 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 output voltage deviation to be minimized and, in turn, to minimize

system costs by providing the fastest response to a load transition.

The L6759D implements current reading across the inductor in fully differential mode. A

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

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

current carried by each phase.

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

registers. The platform may program the defaults for these registers through dedicated pin-

strapping.

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

and total) and feedback disconnection guarantee the load to be safe under all conditions.

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

gate driving voltage and switching frequency to optimize the efficiency over the load range.

The L6759D is available in VFQFPN48 with a 6x6 mm body package.

5.1

Device initialization

Figure 6.

Device initialization: default

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