ISL6329 Datasheet, PDF (35/38 Pages) Intersil Corporation – Dual PWM Controller Powering AMD SVI Split-Plane Processors

ISL6329
Routing UGATE, LGATE, and PHASE Traces
Great attention should be paid to routing the UGATE, LGATE, and
PHASE traces since they drive the power train 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. They should be sized to carry at least one ampere of
current (0.02” to 0.05”). Going between layers with vias should also
be avoided, but if so, use two vias for interconnection when possible.
Extra care should be given to the LGATE traces in particular since
keeping their impedance and inductance low helps to significantly
reduce the possibility of shoot-through. It is also important to route
each channels UGATE and PHASE traces in as close proximity as
possible to reduce their inductances.
Current Sense Component Placement and
Trace Routing
One of the most critical aspects of the ISL6329 regulator layout
is the placement of the inductor DCR current sense components
and traces. The R-C current sense components must be placed
as close to their respective ISEN+ and ISEN- pins on the ISL6329
as possible.
The sense traces that connect the R-C sense components to each
side of the output inductors should be routed on the bottom of
the board, away from the noisy switching components located on
the top of the board. These traces should be routed side by side,
and they should be very thin traces. It’s important to route these
traces as far away from any other noisy traces or planes as
possible. These traces should pick up as little noise as possible.
Thermal Management
For maximum thermal performance in high current, high
switching frequency applications, connecting the thermal GND
pad of the ISL6329 to the ground plane with multiple vias is
recommended. This heat spreading allows the part to achieve
its full thermal potential. It is also recommended that the
controller be placed in a direct path of airflow if possible to help
thermally manage the part.
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FN7800.0
April 19, 2011