Datasheet

LTM4628
28
4628fe
For more information www.linear.com/LTM4628
Safety Considerations
The LTM4628 modules do not provide galvanic isolation
from V
IN
to V
OUT
. There is no internal fuse. If required,
a slow blow fuse with a rating twice the maximum input
current needs to be provided to protect each unit from
catastrophic failure. The device does support thermal
shutdown and over current protection. A temperature
diode is provided for monitoring internal temperature.
Layout Checklist/Example
The high integration of LTM4628 makes the PCB board
layout very simple and easy. However, to optimize its
electrical and thermal performance, some layout consid
-
erations are still necessary.
•
Use large PCB copper areas for high current paths,
including V
IN
, GND, V
OUT1
and V
OUT2
. It helps to mini-
mize the PCB conduction loss and thermal stress.
•
Place high frequency ceramic input and output capaci-
tors next
to the V
IN
, PGND and V
OUT
pins to minimize
high frequency noise.
• Place a dedicated power ground layer underneath the
unit.
• To minimize the via conduction loss and reduce module
thermal stress, use multiple vias for interconnection
between top layer and other power layers.
• Do not put via directly on the pad, unless they are
capped or plated over.
• Use a
separated SGND ground copper area for com-
ponents
connected
to signal pins. Connect the SGND
to GND underneath the unit.
• For parallel modules, tie the V
OUT
, V
FB
, and COMP pins
together. Use an internal layer to closely connect these
pins together. The TRACK pin can be tied a common
capacitor for regulator soft-start.
• Bring out test points on the signal pins for monitoring.
Figure 27 gives a good example of the recommended
layout. LGA and BGA PCB layouts are identical with the
exception of circle pads for BGA (see Package Description).
APPLICATIONS INFORMATION
Figure 27. Recommended PCB Layout (LGA Shown, for BGA Use Circle Pads)
GND
GND GND
SGND
CNTRLCNTRL
V
OUT1
C
OUT1
C
OUT2
V
OUT2
V
IN
C
IN1
C
IN2
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L
K
J
H
G
F
E
D
C
B
M
A
4628 F27