AAT4672ITP-T1 ANALOGICTECH [Advanced Analogic Technologies], AAT4672ITP-T1 Datasheet - Page 8

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

Functional Block Diagram
Truth Table
Y = Yes, N = No, X = don’t care.
Functional Description
To power the OUT pin, at least one of the two input sup-
plies (MAIN/AUX) must be greater than the UVLO thresh-
old. If only one supply is greater than the UVLO thresh-
old, the load will be connected to that particular supply
when the device is enabled. If both supplies are above
the UVLO threshold, the AAT4672 will connect the supply
from the MAIN pin to the OUT pin when the device is
enabled and the MAIN voltage is greater than the AUX
voltage plus 0.2V (typical); otherwise, the AAT4672 will
connect the supply from the AUX pin to the OUT pin.
The two internal power switches are current limited; the
current limits are programmed by the resistors on the
IMAIN and IAUX pins respectively.
8
8
SmartSwitch
SmartSwitch
V
PWRSEL
MAIN
IMAIN
MAIN
IAUX
> UVLO
AUX
N
N
Y
Y
Y
TM
TM
V
Input Conditions
AUX
and Current
Thermal
> UVLO
Sense
N
N
Y
Y
Y
w w w . a n a l o g i c t e c h . c o m
w w w . a n a l o g i c t e c h . c o m
Switch 2
Control
Switch 1
Logic
V
Applications Information
Input Capacitors
A 1µF or greater capacitor is generally recommended
between MAIN and GND (C
GND (C
operation; however, it is useful in preventing load tran-
sients from affecting up-stream circuits. Ceramic, tanta-
lum, or aluminum electrolytic capacitors may be selected
for C
series resistance (ESR) requirement for C
However, for higher current operation, ceramic capaci-
tors are recommended for C
ent capability over tantalum capacitors to withstand
MAIN
MAIN
> V
AUX
/C
AUX
X
X
X
N
Y
). An input capacitor is not required for basic
AUX
+ 0.2V
. There is no specific capacitor equivalent
Power Supply Selector Switch
Power Supply Selector Switch
PRODUCT DATASHEET
PRODUCT DATASHEET
MAIN
MAIN
AAT4672
AAT4672
), and between AUX and
/C
AUX
AAT4672
due to their inher-
Floating
V
V
V
4672.2008.04.1.0
4672.2008.04.1.0
V
V
MAIN
MAIN
OUT
AUX
AUX
OUT
EN
GND
MAIN
/C
AUX
.