Datasheet

LT3652HV
20
3652hvfa
APPLICATIONS INFORMATION
High current paths and transients should be kept iso-
lated from battery ground, to assure an accurate output
voltage reference. Effective grounding can be achieved
by considering switched current in the ground plane,
and careful component placement and orientation can
effectively steer these high currents such that the battery
reference does not get corrupted. Figure 11 illustrates an
effective grounding scheme using component placement
to control ground currents. When the switch is enabled
(loop #1), current flows from the input bypass capacitor
(C
IN
) through the switch and inductor to the battery posi-
SW
V
IN
R
SENSE
SENSE
BAT
V
FB
+
GND
LT3652HV
D
F
C
IN
C
BAT
V
BAT
2
3652 F11
1
Figure 11. Component Orientation Isolates High Current Paths
from Sensitive Nodes
tive terminal. When the switch is disabled (loop #2), the
current to the battery positive terminal is provided from
ground through the freewheeling Schottky diode (D
F
). In
both cases, these switch currents return to ground via the
output bypass capacitor (C
BAT
).
The LT3652HV packaging has been designed to efficiently
remove heat from the IC via the Exposed Pad on the
backside of the package, which is soldered to a copper
footprint on the PCB. This footprint should be made as
large as possible to reduce the thermal resistance of the
IC case to ambient air.