Datasheet

LT3796/LT3796-1
23
3796fa
For more information www.linear.com/3796
Board Layout
The high speed operation of the LT3796/LT3796-1 demands
careful attention to board layout and component placement.
The exposed pad of the package is the GND terminal of
the IC and is also important for thermal management of
the IC. It is crucial to achieve a good electrical and thermal
contact between the exposed pad and the ground plane
of the board. To reduce electromagnetic interference
(EMI), it is important to minimize the area of the high
dV/dt switching node between the inductor, switch drain
and anode of the Schottky rectifier. Use a ground plane
under the switching node to eliminate interplane coupling
to sensitive signals. The lengths of the high dI/dt traces:
1) from the switch node through the switch and sense
resistor to GND, and 2) from the switch node through
the Schottky rectifier and filter capacitor to GND should
be minimized. The ground points of these two switch-
ing current traces should come to a common point then
connect to the ground plane under the LT3796/LT3796-1.
Likewise, the ground terminal of the bypass capacitor for
the INTV
CC
regulator should be placed near the GND of
the switching path. Typically, this requirement results in
the external switch being closest to the IC, along with the
INTV
CC
bypass capacitor. The ground for the compensa-
tion network and other DC control signals should be star
connected to the underside of the IC. Do not extensively
route high impedance signals such as FB1, FB2, RT and
V
C
, as they may pick up switching noise. Since there is a
small variable DC input bias current to the ISN and ISP
inputs, resistance in series with these pins should be
minimized to avoid creating an offset in the current sense
threshold. Likewise, minimize resistance in series with the
SENSE input to avoid changes (most likely reduction) to
the switch current limit threshold.
Figure 10 is a suggested two sided layout for a boost
converter. Note that the 4-layer layout is recommended
for best performance. Please contact the factory for the
reference layout design.
APPLICATIONS INFORMATION