L6711TR datasheet(28/50 Pages) STMICROELECTRONICS

28 / 50 page

Dynamic VID transitions

L6711

28/50

Dynamic VID transitions

The device is able to manage Dynamic VID Code changes that allow Output Voltage

modification during normal device operation.

OVP and UVP signals are masked during every VID transition and they are re-activated

after the transition finishes.

When changing dynamically the regulated voltage (D-VID), the system needs to charge or

discharge the output capacitor accordingly. This means that an extra-current ID-VID needs to

be delivered, especially when increasing the output regulated voltage and it must be

considered when setting the over current threshold. This current result:

where dVOUT is the selected DAC LSB (12.5mV for VRD10.x or 25mV for Hammer DAC)

and TVID is the time interval between each LSB transition.

Overcoming the OC threshold during the dynamic VID causes the device to enter the

constant current limitation slowing down the output voltage dV/dt also causing the failure in

the D-VID test.

The way in which the device modifies the reference depends on the VID_SEL status and

then on the kind of DAC selected.

Figure 13.

Dynamic VID transition, VRD10.x DAC

DVID

–

OUT

⋅

VID

--------------------------------------

Tsw/3

x 4 Step VID Transition

VRD10.x DAC

VID [0,5]

Int. Reference

Vout

Tsw

4 x 1 Step VID Transition - VRD10.x DAC

TVID

VID Clock

L6711TR Datasheet(PDF) 28 Page - STMicroelectronics