AAT4672ITP-T1 ANALOGICTECH [Advanced Analogic Technologies], AAT4672ITP-T1 Datasheet - Page 10

• Manufacturer Part Number: AAT4672ITP-T1
• Description: Power Supply Selector Switch
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

T
the AAT4672 over-temperature protection (thermal
shutdown). With typical specification of 140°C, 125°C is
a safe minimum value to use.
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
to be 300mΩ (from the “R
mance graph, where V
find the maximum current (I
Equation 2:
10
SmartSwitch
SD(MIN)
is the minimum temperature required to activate
I
MAX
Eq. 2:
=
TM
300mΩ · 160 °C/W
I
MAX
125°C - 85°C
IN
=
= 2.5V at 85°C plus 50%). To
DS(ON)
R
T
MAX
DS(ON)(MAX)
SD(MIN)
) for this application, use
vs. Temperature” perfor-
DS(ON)(MAX)
- T
= 0.913A
A(MAX)
· R
ΘJA
is estimated
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 AAT4672,
certain circuit board layout rules should be followed:
MAIN, AUX, and OUT should be routed using wider than
normal traces. The two MAIN pins (1 and 2) and two
AUX 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, input capacitors
(C
as close to the package pins as possible. The AAT4672
evaluation board layout follows the printed circuit board
layout recommendations and can be used as an example
of an optimal board layout.
MAIN
, C
AUX
) and output capacitor (C
Power Supply Selector Switch
PRODUCT DATASHEET
AAT4672
OUT
) should be placed
4672.2008.04.1.0
DS(ON)
val-