ISL8103IRZ Intersil, ISL8103IRZ Datasheet - Page 26

• Manufacturer Part Number: ISL8103IRZ
• Description: IC CTRLR PWM BUCK 3PHASE 40-QFN
• Manufacturer: Intersil

Specifications of ISL8103IRZ

• Pwm Type: Voltage Mode
• Number Of Outputs: 1
• Frequency - Max: 1.5MHz
• Duty Cycle: 66.6%
• Voltage - Supply: 4.75 V ~ 12.6 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-VFQFN, 40-VFQFPN
• Frequency-max: 1.5MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

MOSFETs using short, high current pulses, it is important to
size them as large and as short as possible to reduce their
overall impedance and inductance. Extra care should be
given to the LGATE traces in particular since keeping the
impedance and inductance of these traces helps to
significantly reduce the possibility of shoot-through.
Equidistant placement of the controller to the three power
trains also helps to keep these traces equally short (equal
impedances, resulting in similar driving of both sets of
MOSFETs).
The power components should be placed first. Locate the
input capacitors close to the power switches. Minimize the
length of the connections between the input capacitors, CIN,
and the power switches. Locate the output inductors and
output capacitors between the MOSFETs and the load.
Locate the high-frequency decoupling capacitors (ceramic)
as close as practicable to the decoupling target, making use
of the shortest connection paths to any internal planes, such
as vias to GND immediately next, or even onto the capacitor
solder pad.
The critical small components include the bypass capacitors
for VCC and PVCC. Locate the bypass capacitors, CBP,
close to the device. It is especially important to locate the
components associated with the feedback circuit close to
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ISL8103
their respective controller pins, since they belong to a
high-impedance circuit loop, sensitive to EMI pick-up. It is
also important to place current sense components close to
their respective pins on the ISL8103, including the RISEN
resistors, RS, RCOMP, CCOMP. For proper current sharing
route three separate symmetrical as possible traces from the
corresponding phase node for each RISEN.
A multi-layer printed circuit board is recommended. Figure 27
shows the connections of the critical components for the
converter. Note that capacitors C
each represent numerous physical capacitors. Dedicate one
solid layer, usually the one underneath the component side
of the board, for a ground plane and make all critical
component ground connections with vias to this layer.
Dedicate another solid layer as a power plane and break this
plane into smaller islands of common voltage levels. Keep
the metal runs from the PHASE terminal to inductor L
short. The power plane should support the input power and
output power nodes. Use copper filled polygons on the top
and bottom circuit layers for the phase nodes. Use the
remaining printed circuit layers for small signal wiring. The
wiring traces from the IC to the MOSFETs’ gates and
sources should be sized to carry at least one ampere of
current (0.02” to 0.05”).
xxIN
and C
xxOUT
could
July 21, 2008
OUT
FN9246.1