AAT4674_08 ANALOGICTECH [Advanced Analogic Technologies], AAT4674_08 Datasheet - Page 8

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

Functional Block Diagram
Truth Table
Y = Yes,
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 con-
nected to the OUT pin. Consult the above “Truth Table” for
the summarized 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
8
SmartSwitch
SmartSwitch
V
IN1
N = No, X = don’t care.
> UVLO
N
Y
N
Y
Y
TM
TM
SEL
IIN2
IIN1
IN1
IN2
Input Conditions
V
IN2
> UVLO
N
N
Y
Y
Y
and Current
Thermal
Sense
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
SEL
X
X
X
0
1
Applications Information
Input Capacitors
A 1μF or greater capacitor is generally recommended
between IN1 and GND (C
(C
tion; however, it is useful in preventing load transients
from affecting up-stream circuits. Ceramic, tantalum, or
aluminum electrolytic capacitors may be selected for C
C
tance (ESR) requirement for C
current operation, ceramic capacitors are recommended
for C
capacitors to withstand input current surges from low
impedance sources such as batteries in portable devices.
IN2
IN2
. There is no specific capacitor equivalent series resis-
). An input capacitor is not required for basic opera-
IN1
/C
IN2
due to their inherent capability over tantalum
Power Supply Selector Switch
Power Supply Selector Switch
AAT4674
Floating
Floating
Floating
V
V
V
PRODUCT DATASHEET
PRODUCT DATASHEET
OUT
IN1
IN2
IN1
), and between IN2 and GND
IN1
AAT4674
AAT4674
/C
OUT
EN
GND
IN2
. However, for higher
AAT4674-1
4674.2008.02.1.1
4674.2008.02.1.1
Floating
V
V
V
V
V
OUT
IN1
IN2
IN1
IN2
IN1
/