ISL6539 Intersil Corporation, ISL6539 Datasheet - Page 19

• Manufacturer Part Number: ISL6539
• Description: Wide Input Range Dual PWM Controller with DDR Option
• Manufacturer: Intersil Corporation

Pin 12 and Pin 17, SOFT1 and SOFT2
The soft-start capacitors should be laid out close to this pin.
The other side of the soft-start cap should tie to signal
ground.
Pin 15 and Pin 16, PG1 and PG2 for Dual Switcher
Operation
For dual switcher operations, these two lines are less noise
sensitive. For DDR applications, a capacitor should be
placed to the PG2/REF pin.
Pin 13, DDR
This pin should connect to VCC in DDR applications, and to
signal ground in dual switcher applications.
Pin 14, VIN
This pin connects to battery voltage, and is less noise
sensitive.
Copper size for the Phase Node
Big coppers on both sides of the Phase node introduce
parasitic capacitance. The capacitance of PHASE should be
kept very low to minimize ringing. If ringing is excessive, it
could easily affect current sample information. It would be
best to limit the size of the PHASE node copper in strict
accordance with the current and thermal management of the
application.
Identify the Power and Signal Ground
The input and output capacitors of the converters, the source
terminals of the bottom switching MOSFET PGND1, and
PGND2, should be closely connected to the power ground.
The other components should connect to signal ground.
Signal and power ground are tied together at the negative
terminal of the output capacitors.
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ISL6539
Decoupling Capacitor for Switching MOSFET
It is recommended that ceramic caps be used closely
connected to the drain side of the upper MOSFET, and the
source of the lower MOSFET. This capacitor reduces the
noise and the power loss of the MOSFET. Refer to Figure 11
for the power component placement.
FIGURE 11. A GOOD EXAMPLE POWER COMPONENT
REPLACEMENT. IT SHOWS THE NEGATIVE OF
INPUT AND OUTPUT CAP AND THE SOURCE OF
THE MOSFET ARE TIED AT ONE POINT.