AAT4674_12 Datasheet, PDF (8/12 Pages) Skyworks Solutions Inc. – Power Supply Selector Switch

Functional Block Diagram
IN1
IIN1
SEL
IIN2
IN2
Thermal
and Current
Sense
Switch 1
Logic
Control
Switch 2
DATA SHEET
AAT4674
Power Supply Selector Switch
OUT
EN
GND
Truth Table
Y = Yes, N = No, X = don’t care.
V_IN1 > UVLO
N
Y
N
Y
Y
Input Conditions
V_IN2 > UVLO
N
N
Y
Y
Y
SEL
X
X
X
0
1
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 of the
AAT4674-1 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 AAT4674-1 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 summarized
AA4674-1 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.
Applications Information
Input Capacitors
A 1μF or greater capacitor is generally recommended
between IN1 and GND (C_IN1), and between IN2 and GND
(C_IN2). An input capacitor is not required for basic opera-
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_IN1/
C_IN2. There is no specific capacitor equivalent series resis-
tance (ESR) requirement for C_IN1/C_IN2. However, for higher
current operation, ceramic capacitors are recommended
for C_IN1/C_IN2 due to their inherent capability over tantalum
capacitors to withstand input current surges from low
impedance sources such as batteries in portable devices.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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201911A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012