10
DEMO MANUAL DC236
DESIGN-READY SWITCHERS
The PGND-SGND tie point for the LTC1628 switching
regulator controllers is optimized by connecting the
grounds directly under the IC, creating a close surface
grounding plane.
The capacitor on INTV
CC
acts as a reservoir to supply the
high transient currents to the bottom gates
and to
recharge the boost capacitor. This capacitor should be a
10
µ
F ceramic capacitor or a 1
µ
F ceramic capacitor in
parallel with a 4.7
µ
F tantalum capacitor. The ceramic
capacitor must be placed as close as possible to the
INTV
CC
and PGND pins of the IC. Peak currents exceed 1A
when charging the gates of the bottom MOSFETs.
Component Side Silkscreen
Copper Layer 1 Top
The traces that sense the voltage across the current-
sensing resistor can be long but should run parallel to each
other and be spaced with the minimum separation allowed
in order to experience the same electrostatic and electro-
magnetic fields from radiating sources. The traces should
be wider than minimum if they are long in order to
minimize self-inductance. Keep these traces on a PC board
plane farthest from the high current and large switching
voltage plane. Any filtering resistors in series with these
traces should be placed close to the IC rather than close to
radiating nodes, such as the switch and boost nodes.
OPERATIO
U
PCB LAYOUT A D FIL
U
W
