ISL6323EVAL1Z Intersil, ISL6323EVAL1Z Datasheet - Page 26

• Manufacturer Part Number: ISL6323EVAL1Z
• Description: EVAL BOARD 1 FOR ISL6323
• Manufacturer: Intersil

Specifications of ISL6323EVAL1Z

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

number of active phases. The I
quiescent power of the controller without load on the drives.
The total gate drive power losses are dissipated among the
resistive components along the transition path and in the
bootstrap diode. The portion of the total power dissipated in
the controller itself is the power dissipated in the upper drive
path resistance (P
(P
the power will be dissipated by the external gate resistors
(R
R
upper and lower gate drives turn-on transition path. The total
power dissipation in the controller itself, P
estimated as Equation 30:
P
P
P
R
P
GI2
FIGURE 19. TYPICAL LOWER-GATE DRIVE TURN-ON PATH
DR
DR_UP
DR_LOW
FIGURE 18. TYPICAL UPPER-GATE DRIVE TURN-ON PATH
EXT1
PVCC
BOOT
DR_UP
G1
PVCC
) of the MOSFETs. Figures 18 and 19 show the typical
=
and R
P
=
=
) and in the boot strap diode (P
DR_UP
=
PHASE
R
=
P
---------------------
R
⎛
⎜
⎝
R
G1
G2
LO2
Qg_Q1
--------------------------------------
R
BOOT
HI2
⎛
⎜
⎝
R
R
HI1
--------------------------------------
R
3
LO1
) and the internal gate resistors (R
+
HI1
HI2
+
R
-------------
R
N
+
P
GI1
HI1
Q1
DR_UP
R
R
+
DR_LOW
HI2
EXT1
R
LGATE
EXT2
UGATE
) the lower drive path resistance
+
+
--------------------------------------- -
R
+
26
LO1
--------------------------------------- -
R
P
R
Q
LO2
BOOT
EXT2
R
R
*VCC product is the
G2
R
+
LO1
R
G
G1
+
R
LO2
G
EXT1
R
+
=
R
C
EXT2
GI2
(
GD
R
R
C
I
C
Q
GI1
GD
BOOT
G2
GS
DR
⎞ P
⎟
⎠
C
⋅
VCC
⋅
⎞ P
⎟
⎠
GS
+
---------------------
, can be roughly
⋅
S
Qg_Q1
---------------------
R
-------------
N
). The rest of
Qg_Q2
GI2
S
3
Q2
)
2
GI1
D
D
Q2
C
and
(EQ. 30)
Q1
DS
C
DS
ISL6323
Inductor DCR Current Sensing Component
Selection and R
With the single R
effective internal sense resistors for both the North Bridge
and Core regulators, it is important to set the R
and the inductor RC filter gain, K, properly. See “Continuous
Current Sampling” on page 13 and “Channel-Current
Balance” on page 14 for more details on the application of
the R
There are 3 separate cases to consider when calculating
these component values. If the system under design will
never utilize the North Bridge regulator and the ISL6323 will
always be in parallel mode, then follow the instructions for
Case 3 and only calculate values for Core regulator
components.
For all three cases, use the expected VID voltage that would
be used at TDC for Core and North Bridge for the V
and V
CASE 1
In Case 1, the DC voltage across the North Bridge inductor
at full load is less than the DC voltage across a single phase
of the Core regulator while at full load. Here, the DC voltage
across the Core inductors must be scaled down to match the
DC voltage across the North Bridge inductor, which will be
impressed across the ISEN_NB pins without any gain. So,
the R
unpopulated and K = 1.
Where: K = 1
K
R
I
R
NB
1. Choose a capacitor value for the North Bridge RC filter. A
2. Calculate the value for resistor R
3. Calculate the value for the R
4. Using Equation 34 (also derived from Equation 20),
5. Choose a capacitor value for the Core RC filters. A 0.1µF
SET
1
=
NB
MAX
0.1µF capacitor is a recommended starting point.
Equation 33: (Derived from Equation 20).
calculate the value of K for the Core regulator.
capacitor is a recommended starting point.
--------- - R
400
SET
2
3
NB
=
=
resistor for the North Bridge inductor RC filter is left
⋅
400
--------- -
⋅
------------------------------------- -
DCR
DCR
variables, respectively.
3
resistor and the RC filter gain.
SET
⋅
L
NB
DCR
----------------------------- -
NB
NB
⋅
100μA
----------------------------- -
DCR
⋅
SET
<
C
NB
I
-------------------------- DCR
SET
NB
Core
N
CORE
⋅
resistor setting the value of the
N
K
MAX
Value Calculation
⋅
⎛
⎜
⎝
I
OCP
⋅
-----------------------------------------------------------------------------------------------------------
I
⋅
OCP
NB
SET
CORE
Core
+
---------------------------- -
2 L
V
1
resistor using
IN
⋅
using Equation 32:
+
NB
–
V
-------------------------------------------- -
V
2 L
IN
⋅
NB
100μA
⋅
f
S
–
CORE
N
⋅
SET
V
-----------
V
⋅
October 21, 2008
NB
IN
V
CORE
⎞
⎟
⎠
value
CORE
⋅
(EQ. 32)
(EQ. 33)
(EQ. 34)
(EQ. 31)
f
S
FN9278.4
⋅
V
------------------- -
CORE
V
IN