AAT4674_08 ANALOGICTECH [Advanced Analogic Technologies], AAT4674_08 Datasheet - Page 10

• Manufacturer Part Number: AAT4674_08
• Description: Power Supply Selector Switch
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

For example, for a 2.5V input power supply application
that is specified to operate in 50°C environments where
the PCB operates at temperatures as high as 85°C. The
application is sealed and its PCB is small, causing R
be approximately 160°C/W. The R
be 300mΩ (from the “R
mance graph, where V
find the maximum current (I
Equation 2:
10
SmartSwitch
I
MAX
=
TM
300mΩ · 160 °C/W
125°C - 85°C
IN
= 2.5V at 85°C plus 50%). To
DS(ON)
MAX
vs. Temperature” perfor-
) for this application use
DS(ON)(MAX)
= 0.913A
is estimate to
w w w . a n a l o g i c t e c h . c o m
θJA
to
PCB Layout Recommendations
For proper thermal management, to minimize PCB trace
resistance, and to take advantage of the low R
ues of the two internal power switches in the
AAT4674/4674-1, certain circuit board layout rules
should be followed: IN1, IN2, and OUT should be routed
using wider than normal traces. The two IN1 pins (1 and
2) and two IN2 pins (3 and 4) should be connected to
the same wide PCB trace; and GND should be connected
to a ground plane. For best performance, the input
capacitors (C
be placed as close to the package pins as possible. The
AAT4674/4674-1 evaluation board layout follows the
printed circuit board layout recommendations and can
be used as an example of an optimal board layout.
IN1
/C
Power Supply Selector Switch
IN2
) and output capacitors (C
PRODUCT DATASHEET
AAT4674
4674.2008.02.1.1
OUT
DS(ON)
) should
val-