ISL6336BIRZ Intersil, ISL6336BIRZ Datasheet - Page 27

• Manufacturer Part Number: ISL6336BIRZ
• Description: IC CTRLR PWM SYNC BUCK 48-QFN
• Manufacturer: Intersil

Specifications of ISL6336BIRZ

• Applications: Controller, Intel VR11.1
• Voltage - Input: 3 ~ 12 V
• Number Of Outputs: 1
• Voltage - Output: 0.5 ~ 1.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-VQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The feedback resistor, R
outlined in “Load-Line Regulation Resistor” on page 26.
Select a target bandwidth for the compensated system, f
The target bandwidth must be large enough to ensure
adequate transient performance, but generally smaller than
1/3 of the per-channel switching frequency. The values of the
compensation components depend on the relationships of f
to the L-C pole frequency and the ESR zero frequency. For
each of the three cases which follow, there are a separate
set of equations for the compensation components.
In Equation 37, L is the per-channel filter inductance divided
by the number of active channels; C is the sum total of all
output capacitors; ESR is the equivalent-series resistance of
the bulk output-filter capacitance; and V
peak-to-peak sawtooth signal amplitude as described in the
“Electrical Specifications” table beginning on page 7.
Case 1:
Case 2:
Case 3:
FIGURE 19. COMPENSATION CONFIGURATION FOR
R
FB
LOAD-LINE REGULATED ISL6336B CIRCUIT
-------------------
2π LC
R
C
-------------------
2π LC
R
C
f
R
C
V
0
+
-
C
C
C
C
C
C
DROOP
R
>
1
1
C
=
=
=
=
----------------------------- -
2πC ESR
=
=
C
R
R
-------------------------------------
2πV
--------------------------------------------------------------
(
R
0.75V
------------------------------------------------ -
FB
2π
2πV
2
>
≤
FB
FB
FB
C
(
(OPTIONAL)
1
0.75V
f
f
, has already been chosen as
)
C
0
0
P-P
2πf
------------------------------------- -
V
--------------------------------------------- -
2
----------------------------------------- -
0.75 V
P-P
27
<
P-P
f
IN
0
----------------------------- -
2πC ESR
2π f
0.75V
0.75V
R
2
0
)
(
0.75 V
R
IN
V
V
FB
(
ESR
2π
FB
P-P
P-P
COMP
VDIFF
0
IN
(
f
1
V
0
)
f
IN
IN
2
0
P-P
R
(
FB
) C
IN
ESR
f
LC
FB
0
L
2
P-P
L
)
LC
ISL6336B
LC
)
is the
(EQ. 37)
0
.
ISL6336B
0
The optional capacitor C
noise away from the PWM comparator (see Figure 19). Keep
a position available for C
frequency capacitor between 22pF and 150pF in case
excessive jitter is noted.
Once selected, the compensation values in Equation 37
ensure a stable converter with reasonable transient
performance. In most cases, transient performance can be
improved by making adjustments to R
value of R
oscilloscope until no further improvement is noted. Normally,
C
Equation 37 unless some performance issue is noted.
C
performance per the type III compensation discussion in the
following.
COMPENSATION WITHOUT LOAD-LINE REGULATION
The non load-line regulated converter is accurately modeled
as a voltage-mode regulator with two poles at the L-C
resonant frequency and a zero at the ESR frequency. A
type III controller, as shown in Figure 20, provides the
necessary compensation.
The first step is to choose the desired bandwidth, f
compensated system. Choose a frequency high enough to
ensure adequate transient performance but generally not
higher than 1/3 of the switching frequency. The type-III
compensator has an extra high-frequency pole, f
pole can be used for added noise rejection or to ensure
adequate attenuation at the error-amplifier high-order pole
and zero frequencies. A good general rule is to choose
f
lower than 10f
shift below the system bandwidth.
In the solutions to the compensation equations, there is a
single degree of freedom. For the solutions presented in
Equation 38, R
HF
C
1
FIGURE 20. COMPENSATION CIRCUIT FOR ISL6336B BASED
and R
will not need adjustment. Keep the value of C
= 10f
C
R
1
1
0
1
C
, but it can be higher if desired. Choosing f
can also be added to improve transient
while observing the transient performance on an
CONVERTER WITHOUT LOAD-LINE
REGULATION
0
FB
can cause problems with too much phase
is selected arbitrarily. The remaining
R
FB
R
C
C
2
2
2
, is sometimes needed to bypass
, and be prepared to install a high
C
C
COMP
VDIFF
FB
C
. Slowly increase the
ISL6336B
HF
August 31, 2010
C
0
. This
from
, of the
HF
FN6696.2
to be