ISL6563 Intersil Corporation, ISL6563 Datasheet - Page 17

• Manufacturer Part Number: ISL6563
• Description: Two-Phase Multi-Phase Buck PWM Controller with Integrated MOSFET Drivers
• Manufacturer: Intersil Corporation

Component Selection Guidelines
Output Capacitor Selection
The output capacitor is selected to meet both the dynamic
load requirements and the voltage ripple requirements. The
load transient a microprocessor impresses is characterized
by high slew rate (di/dt) current demands. In general,
multiple high quality capacitors of different size and dielectric
are paralleled to meet the design constraints.
Should the load be characterized by high slew rates, attention
should be particularly paid to the selection and placement of
high-frequency decoupling capacitors (MLCCs, typically -
multi-layer ceramic capacitors). High frequency capacitors
supply the initially transient current and slow the load rate-of-
change seen by the bulk capacitors. The bulk filter capacitor
values are generally determined by the ESR (effective series
resistance) and capacitance requirements.
+12V
+5V
R’
IN
R
IN
OFS
OFS
C
R
R
R
2
2
2
1
(MINIMIZE CONNECTION PATH)
DACSEL/VID12
R
LOCATE CLOSE TO IC
ISEN
(C
F1
SSEND
VRM10
C
COMP
)
ENLL
VID4
VID3
VID2
VID1
VID0
ISEN
1
OFS
FB
17
FIGURE 9. PRINTED CIRCUIT BOARD POWER PLANES AND ISLANDS
VCC
ISL6563
PVCC
(C
F2
)
PHASE1
UGATE2
PHASE2
BOOT1
UGATE1
LGATE1
BOOT2
LGATE2
PGND
GND
L
IN
ISL6563
C
C
BOOT1
BOOT2
LOCATE NEAR SWITCHING TRANSISTORS;
High frequency decoupling capacitors should be placed as
close to the power pins of the load, or for that reason, to any
decoupling target they are meant for, as physically possible.
Attention should be paid as not to add inductance in the
circuit board wiring that could cancel the usefulness of these
low inductance components. Consult with the manufacturer
of the load on specific decoupling requirements.
Use only specialized low-ESR capacitors intended for
switching-regulator applications for the bulk capacitors. The
bulk capacitor’s ESR determines the output ripple voltage
and the initial voltage drop following a high slew-rate
transient’s edge. In most cases, multiple capacitors of small
case size perform better than a single large case capacitor.
Bulk capacitor choices include aluminum electrolytic, OS-Con,
Tantalum and even ceramic dielectrics. An aluminum
electrolytic capacitor’s ESR value is related to the case size
(MINIMIZE CONNECTION PATH)
Q4
Q2
Q3
Q1
(C
HFIN1
(C
KEY
HFIN2
L
L
)
HEAVY TRACE ON CIRCUIT PLANE LAYER
ISLAND ON POWER PLANE LAYER
ISLAND ON CIRCUIT PLANE LAYER
VIA CONNECTION TO GROUND PLANE
OUT1
OUT2
)
C
BIN2
C
BIN1
(MINIMIZE CONNECTION PATH)
LOCATE NEAR LOAD;
C
BOUT
(C
HFOUT
)
V
OUT