AAT4674 Datasheet, PDF (8/13 Pages) Advanced Analogic Technologies – Power Supply Selector Switch

Functional Block Diagram
IN1
IIN1
SEL
IIN2
IN2
Thermal
and Current
Sense
AAT4674
Power Supply Selector Switch
Switch 1
Logic
Control
Switch 2
OUT
EN
GND
Truth Table
Input Conditions
V_IN1 > UVLO
N
Y
N
Y
Y
V_IN2 > UVLO
N
N
Y
Y
Y
Y = Yes, N = No, X = don’t care.
SEL
X
X
X
0
1
AAT4674
V_OUT
Floating
Floating
Floating
V_IN1
V_IN2
AAT4674-1
V_OUT
Floating
V_IN1
V_IN2
V_IN1
V_IN2
Functional Description
To power the output, both input supplies (IN1 and
IN2) must be above the UVLO threshold. If either
supply input is below the UVLO threshold then the
output will float or, in the case of the AAT4674-1
the output will be the input supply that is above the
UVLO threshold. If both supplies are above the
UVLO threshold and the device is enabled, the
AAT4674/AAT4674-1 will connect the supply from
IN1 to OUT when the SEL pin is LOW (logic ‘0’),
and when the SEL pin is HIGH (logic ‘1’) then the
supply on IN2 is connected to the OUT pin.
Consult the above “Truth Table” for the summa-
rized AA4674/4674-1 operational details.
The two internal power switches are current limited
and the limiting thresholds can be programmed
through the resistors on the IIN1 and IIN2 pins
respectively.
8
4674.2007.09.1.0