Datasheet

LTC3606B
14
3606bfb
Figure 3a. LTC3606B Layout Diagram (See Board Layout Checklist)
APPLICATIONS INFORMATION
C
F
R
LIM
R
PGD
V
IN
2.5V TO 5.5V
V
OUT
3606B F03a
R1
L1
R2
C
IN
C
OUT
BOLD LINES INDICATE HIGH CURRENT PATHS
C
LIM
V
IN
LTC3606B
SW
V
FB
GND
RLIM
RUN
PGOOD
PC Board Layout Considerations
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the LTC3606B. These items are also illustrated graphically
in the layout diagrams of Figures 3a and 3b. Check the
following in your layout:
1. Does the capacitor C
IN
connect to the power V
IN
(Pin 5)
and GND (Pin 9) as closely as possible? This capacitor
provides the AC current of the internal power MOSFETs
and their drivers.
2. Are the respective C
OUT
and L closely connected? The
(–) plate of C
OUT
returns current to GND and the (–)
plate of C
IN
.
3. The resistor divider, R1 and R2, must be connected
between the (+) plate of C
OUT
and a ground sense line
terminated near GND (Pin 9). The feedback signal V
FB
should be routed away from noisy components and
traces, such as the SW line (Pin 4), and their trace
length should be minimized.
4. Keep sensitive components away from the SW pin, if
possible. The input capacitor C
IN
, C
LIM
and the resistors
R1, R2, and R
LIM
should be routed away from the SW
traces and the inductors.
5. A ground plane is preferred, but if not available, keep
the signal and power grounds segregated with small
signal components returning to the GND pin at a single
point. These ground traces should not share the high
current path of C
IN
or C
OUT
.
6. Flood all unused areas on all layers with copper.
Flooding with copper will reduce the temperature rise
of power components. These copper areas should be
connected to V
IN
or GND.