SG6932 Fairchild Semiconductor, SG6932 Datasheet - Page 16

• Manufacturer Part Number: SG6932
• Description: The highly integrated SG6932 is designed for power supplies with boost PFC and forward PWM
• Manufacturer: Fairchild Semiconductor

© 2007 Fairchild Semiconductor Corporation
SG6932 • Rev. 1.1.3
PCB Layout
SG6932 has a single ground pin, which prevents high
sink currents in the output being returned separately.
Good high-frequency or RF layout practices should be
followed. Avoid long PCB traces and component leads.
Locate decoupling capacitors near the SG6932. A
resistor (5 ~ 20Ω) is recommended, connected in
series from the output to the gate of the MOSFET.
Isolating the interference between the PFC and PWM
stages is also important. Figure 32 shows an example
of the PCB layout. The ground trace 1 is connected
from the ground pin to the decoupling capacitor, which
should be low impedance and as short as possible. The
ground trace 2 provides a signal ground and should be
connected directly to the decoupling capacitor C
and/or to the ground pin. The ground trace 3 is
independently tied from the decoupling capacitor to the
PFC output capacitor C
O
.
Figure 32. PCB Layout
DD
16
The ground in the output capacitor C
ground reference for power switching. To provide a
good ground reference and reduce the switching noise
of both the PFC and PWM stages, the ground traces 6
and 7 should be located very near and be low
impedance.
The IPFC pin is connected directly to R
improve noise immunity. Do not incorrectly connect
to the ground trace 2. The IMP and ISENSE pins
should also be connected directly via the resistors R
and R
P
to another terminal of R
S
.
S
O
through R
is the major
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3
to
2