ISL6324A Datasheet, PDF (31/39 Pages) Intersil Corporation – Monolithic Dual PWM Hybrid Controller Powering AMD SVI Split-Plane and PVI Uniplane Processors

ISL6324A
the R₂ resistor for the North Bridge inductor RC filter is left
unpopulated and K = 1.
3. Choose a capacitor value for the North Bridge RC filter. A
0.1µF capacitor is a recommended starting point.
4. Calculate the value for resistor R₁ using Equation 30:
R_1NB = _D-----_C-----_R----^L-_N---^N-_B---^B--_â‹---_C----_N-----_B-
(EQ. 30)
5. Calculate the value for the R_SET resistor using
Equation 31: (Derived from Equation 18).
R_SET
=
4_----0_---0_--
3
⋅
D_-----C_-----R_{-----N----B-----}⋅_---K_--
100 μ A
⋅
⎛
⎜
⎝
I_O
C
PN
B
+
-^V----^I--^N------–----^V----^N----^B---
2 ⋅ L_NB ⋅ f_S
⋅
-^V-_V---^N-_I--_N-^B--_{⎠⎟⎞}
Where: K = 1
(EQ. 31)
6. Using Equation 32 (also derived from Equation 18),
calculate the value of K for the Core regulator.
K
=
----³-----
400
⋅
R_SE
T
⋅
--------------^N---------------
DCR_CORE
⋅
---------------------------------------------¹----⁰---⁰----^μ----^A-----------------------------------------------
I_OC
PC
O
R
E
+
V_{-----I--N-----–----}N_------⋅_---V_{----C-----O----R----E--}
2 ⋅ L_CORE ⋅ f_S
⋅
-^V----^C----^O----^R-----^E--
V_IN
(EQ. 32)
7. Choose a capacitor value for the Core RC filters. A 0.1µF
capacitor is a recommended starting point.
8. Calculate the values for R₁ and R₂ for Core.
Equations 33 and 34 will allow for their computation.
K
=
--------------^R----²----^C----^o---^r--^e---------------
R_1Core + R_2Core
(EQ. 33)
------^L---^C-----^o---^r--^e-------
DCR_Core
=
-^R-----¹---^C----^o----^r--^e----^â‹---^R-----²---^C----^o---^r---^e--
R_1Core + R_2Core
⋅
C_Co
re
(EQ. 34)
CASE 2
I_NBM
A
X
⋅
D
C
R_NB
>
I_{--C-----o---r--e---M-----A----X--}
N
⋅
D
C
R_C
o
r
e
(EQ. 35)
In Case 2, the DC voltage across the North Bridge inductor
at full load is greater than the DC voltage across a single
phase of the Core regulator while at full load. Here, the DC
voltage across the North Bridge inductor must be scaled
down to match the DC voltage across the Core inductors,
which will be impressed across the ISEN pins without any
gain. So, the R₂ resistor for the Core inductor RC filters is
left unpopulated and K = 1.
1. Choose a capacitor value for the Core RC filter. A 0.1µF
capacitor is a recommended starting point.
2. Calculate the value for resistor R₁:
R_1Core
=
-----------------^L---^C----^o----^r--^e-----------------
DCR_Core ⋅ C_Core
(EQ. 36)
3. Calculate the value for the R_SET resistor using
Equation 37:(Derived from Equation 18).
R_SET
=
4_----0_---0_--
3
⋅
-^D----^C-----^R-----^C----^O----^R-----^E-----^â‹---^K--
100μA ⋅ N
⋅
⎛
⎜
⎝
I_O
C
PCOR
E
+
-^V----^I--^N-----–-----^V----^C----^O-----^R----^E---
2 ⋅ L_CORE ⋅ f_S
⋅
-^V----^C-_V---^O-_I--_N-^R-----^E--_{⎠⎟⎞}
Where: K = 1
(EQ. 37)
4. Using Equation 38 (also derived from Equation 18),
calculate the value of K for the North bridge regulator.
K
=
----³-----
400
⋅
R_SET
⋅
----------¹-----------
DCR_NB
⋅
----------------------------¹----⁰---⁰----^μ----^A------------------------------
I_O
C
PN
B
+
-^V----^I--^N------–----^V----^N----^B---
2 ⋅ L_NB ⋅ f_S
⋅
-^V----^N----^B--
V_IN
(EQ. 38)
5. Choose a capacitor value for the North Bridge RC filter. A
0.1µF capacitor is a recommended starting point.
6. Calculate the values for R₁ and R₂ for North Bridge.
Equations 39 and 40 will allow for their computation.
K
=
-----------^R-----²---^N----^B-------------
R_1NB + R_2NB
(EQ. 39)
------^L---^N-----^B-------
DCR_NB
=
-^R-----¹---^N----^B-----^â‹---^R-----²---^N----^B---
R_1NB + R_2NB
⋅
C_NB
(EQ. 40)
CASE 3
I_NBMAX ⋅ DCR_NB
=
I_{--C-----o---r--e---M-----A----X--}
N
⋅
D
CR_C
o
re
(EQ. 41)
In Case 3, the DC voltage across the North Bridge inductor
at full load is equal to the DC voltage across a single phase
of the Core regulator while at full load. Here, the full scale
DC inductor voltages for both North Bridge and Core will be
impressed across the ISEN pins without any gain. So, the R₂
resistors for the Core and North Bridge inductor RC filters
are left unpopulated and K = 1 for both regulators.
For this Case, it is recommended that the overcurrent trip
point for the North Bridge regulator be equal to the
overcurrent trip point for the Core regulator divided by the
number of core phases.
1. Choose a capacitor value for the North Bridge RC filter. A
0.1µF capacitor is a recommended starting point.
2. Calculate the value for the North Bridge resistor R₁:
R_1NB
=
--------------^L----^N----^B---------------
DCR_NB ⋅ C_NB
(EQ. 42)
3. Choose a capacitor value for the Core RC filter. A 0.1µF
capacitor is a recommended starting point.
4. Calculate the value for the Core resistor R₁:
R_1Core = -_D----_C-----_R-----_C--^L--_o-^C--_r--_eo----^r-_â‹-^e--_C----_C----_o----_r--_e-
(EQ. 43)
31
FN6880.1
April 29, 2010