L6713ATR datasheet(35/64 Pages) STMICROELECTRONICS

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L6713A

Voltage positioning

35/64

Voltage positioning

Output voltage positioning is performed by selecting the reference DAC and by

programming the droop function and offset to the reference (See Figure 11). The currents

sourced from DROOP and sunk from VSEN pins cause the output voltage to vary according

to the external RFB and ROFFSET resistor.

The output voltage is then driven by the following relationship:

DROOP function can be disabled as well as the OFFSET: connecting DROOP pin and FB

pin together implements the load regulation dependence while, if this effect is not desired,

by shorting DROOP pin to SGND it is possible for the device to operate as a classic voltage

mode buck converter. The DROOP pin can also be connected to SGND through a resistor

obtaining a voltage proportional to the delivered current usable for monitoring purposes.

OFFSET can be disabled by using ROFFSET equal to zero.

Figure 11.

Voltage positioning (left) and droop function (right)

12.1

Offset (Optional)

The IOFFSET current (See Table 5) sunk from the VSEN pin allows programming a positive

offset (VOS) for the output voltage by connecting a resistor ROFFSET between VSEN pin and

VOUT, as shown in the Figure 11; this offset has to be considered in addition to the one

already introduced during the production stage for the Intel VR10,VR11 mode.

The output voltage is then programmed as follow:

Offset resistor can be designed by considering the following relationship:

Offset automatically given by the DAC selection differs from the offset implemented through

the IOFFSET current: the built-in feature is trimmed in production and assures ± 0.5 % error

(± 0.6 % for the AMD DAC) over load and line variations.

OUT

REF

OFFSET

() I

DROOP

()

OFFSET

() I

OFFSET

()

⋅

–

REF

VID

19mV

–

VR10 - VR11

VID

AMD 6BIT

⎩

⎨

⎧

COMP

To GND_core

(Remote Sense)

ERROR AMPLIFIER

FBG

DROOP

VSEN

DROOP

To VCC_core

(Remote Sense)

RFB

ROFFSET

VPROG

VREF

FBG

VSEN

GND DROP

RECOVERY

OFFSET

ESR Drop

VMAX

VMIN

VNOM

RESPONSE WITHOUT DROOP

RESPONSE WITH DROOP

OUT

REF

OFFSET

() I

DROOP

()

OFFSET

() I

OFFSET

()

⋅

–

OFFSET

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L6713ATR Datasheet(PDF) 35 Page - STMicroelectronics

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