l6706 STMicroelectronics, l6706 Datasheet - Page 28

• Manufacturer Part Number: l6706
• Description: Vr11.1 Single Phase Controller With Integrated Driver
• Manufacturer: STMicroelectronics

Dynamic VID transitions
12
Note:
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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 with a
transition.
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 I
be delivered, especially when increasing the output regulated voltage and it must be
considered when setting the over current threshold.
This current can be estimated using the following relationships:
where d
between each LSB transition (externally driven).
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. In order to avoid this situation the device automatically increases the OCP
threshold to 150% of the selected OCP threshold during every VID transition (adding an
extra
L6706 checks for VID code modifications (see
additional DVID-clock and waits for a confirmation on the following falling edge. Once the
new code is stable, on the next rising edge, the reference starts stepping up or down in LSB
increments every VID-clock cycle until the new VID code is reached. During the transition,
VID code changes are ignored; the device re-starts monitoring VID after the transition has
finished on the next rising edge available. VID-clock frequency (F
MHz to assure compatibility with the specifications.
If the new VID code is more than 1 LSB different from the previous, the device will execute
the transition stepping the reference with the DVID-clock frequency F
has reached: for this reason it is recommended to carefully control the VID change rate in
order to carefully control the slope of the output voltage.
15 µs
VOUT
of delay).
is the selected DAC LSB (6.25 mV for VR11.1) and T
Doc ID 15698 Rev 1
15 µs
I
D VID
–
(typ) delay to prevent from false triggering due to the
=
C
OUT
Figure
⋅
dV
----------------- -
dT
OUT
VID
12) on the rising edge of an internal
DVID
VID
DVID
) is in the range of 1.8
is the time interval
until the new code
D-VID
needs to
L6706