Datasheet

LTM4601AHV
19
4601ahvfc
For more information www.linear.com/LTM4601AHV
Figure 17. Recommended Layout
(LGA and BGA PCB Layouts Are Identical with the Exception of Circle Pads for BGA. See Package Description.)
applicaTions inForMaTion
SIGNAL
GND
CONTROL
CONTROL
CONTROL
4601AHV F17
V
OUT
V
IN
PGND
C
OUT
C
OUT
C
IN
C
IN
Safety Considerations
The LTM4601AHV modules do not provide 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.
Layout Checklist/Example
The high integration of LTM4601AHV makes the PCB
board layout very simple and easy. However, to optimize
its electrical and thermal performance, some layout con
-
siderations are still necessary.
•
Use large PCB copper areas for high current path, in-
cluding V
IN
, PGND and V
OUT
. It helps to minimize 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. Refer frequency synchronization source to power
ground.
• 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 vias directly on pads unless they are capped.
• Use a separated SGND ground copper area for com
-
ponents connected to signal pins. Connect the SGND
to PGND underneath the unit.
Figure 17 gives a good example of the recommended layout.
Frequency Adjustment
The L
TM4601AHV is designed to typically operate at 850kHz
across most input conditions. The f
SET
pin is normally
left open. The switching frequency has been optimized
for maintaining constant output ripple noise over most
operating ranges. The 850kHz switching frequency and
the 400ns minimum off time can limit operation at higher
duty cycles like 5V to 3.3V, and produce excessive induc
-
tor ripple currents for lower duty cycle applications like
28V to 5V. The 5V
OUT
and 3.3V
OUT
drop out curves are
modified by adding an external resistor on the f
SET
pin to
allow for lower input voltage operation, or higher input
voltage operation.