isl6363 Intersil Corporation, isl6363 Datasheet - Page 30

• Manufacturer Part Number: isl6363
• Description: Multiphase Pwm Regulator For Vr12™ Desktop Cpus
• Manufacturer: Intersil Corporation

Figure 27 shows the waveforms of 1-tick VID transition. During
1-tick VID transition, the DAC output changes at approximately
15mV/µs slew rate, but the DAC cannot step through multiple
VIDs to control the slew rate. Instead, the control loop response
speed determines V
FB pin voltage slew rate. However, the controller senses the
inductor current increase during the up transition, as the
I
V
behavior occurs during the down transition.
To control V
add the R
When V
induced I
Where C
In the mean time, the R
expression is:
I
I
droop_vid
droop
vid
CORE
t ( )
t ( )
accordingly, making V
=
CORE
out
droop
C
=
vid
waveform shows, and will droop the output voltage
vid
CORE
C
----------------------- -
is the total output capacitance.
-C
R
out
increases, the time domain expression of the
×
vid
droop
change is:
dV
----------- -
dt
×
slew rate during 1-tick VID transition, one can
branch, whose current I
fb
LL
CORE
×
×
⎛
⎜
⎜
⎝
dV
----------------- -
1 e
vid
–
dt
core
slew rate. Ideally, V
-C
----------------------------- -
R
vid
vid
CORE
×
30
t –
⎛
⎜
⎜
⎝
×
branch current I
1 e
C
–
vid
slew rate slow. Similar
⎞
⎟
⎟
⎠
------------------------ -
C out
t –
vid
×
LL
cancels I
⎞
⎟
⎟
⎠
CORE
vid
will follow the
time domain
droop_vid
(EQ. 43)
(EQ. 44)
ISL6363
.
It is desired to let I
and:
The result is expressed in Equation 47:
and:
C
For example: given LL = 1.9mΩ, R
C
Equation 47 gives R
C
It is recommended to select the calculated R
with the calculated C
get the best performance.
During normal transient response, the FB pin voltage is held
constant, therefore is virtual ground in small signal sense. The
R
ground, and hence has no effect on transient response.
C
R
R
vid
out
vid
vid
vid
vid
vid
= 700pF.
- C
×
×
= 1320µF, dV
=
=
dV
----------- -
C
vid
C
----------------------- -
dt
R
vid
R
out
fb
droop
droop
network is between the virtual ground and the real
=
=
×
C
LL
C
----------------------- -
out
R
out
droop
×
----------------- -
×
dV
----------------- -
vid
×
CORE
dV
----------- -
LL
vid
LL
dt
dt
core
vid
(t) cancel I
fb
×
= 2.37kΩ and Equation 48 gives
/dt = 10mV/µs and dV
value and tweak it on the actual board to
dV
----------------- -
dt
core
droop_vid
droop
= 2.37kΩ,
(t). So there are:
vid
fb
/dt = 15mV/µs,
value and start
September 29, 2011
FN6898.0
(EQ. 45)
(EQ. 46)
(EQ. 48)
(EQ. 47)