SmartSwitch
™
AAT4651
5V/3V PC Card Power Switch
4651.2006.05.1.2 1
General Description
The AAT4651 SmartSwitch is a single channel PC
card (PCMCIA) power switch. It is used to select
between two different voltage inputs, each between
2.7V and 5.5V. An internal switch powers the cir-
cuitry from whichever input voltage is higher. The
device's output, V
CC
, is slew rate controlled and cur-
rent limited, in compliance with PC card specifica-
tions. The current limit response time to a short cir-
cuit is typically 1µs. The internal P-channel MOS-
FET switches are configured to break before make;
that is, both switches cannot be closed at the same
time. Controlled by a 2-bit parallel interface, the
three states for V
CC
are V
CC5
, V
CC3
, or ground.
When in the ground state, V
CC
is pulled to ground by
an 200Ω resistor. An open drain FAULT output is
asserted during over-current conditions. During
power-up slewing, FAULT also signals that V
CC
is
out of tolerance. An internal over-temperature sen-
sor forces V
CC
to a high impedance state when an
over-temperature condition exists. Quiescent cur-
rent is typically a low 15µA, as long as I
CC
is less
than approximately 500mA. Above this load current,
the quiescent current increases to 200µA.
The AAT4651 is available in a Pb-free, 8-pin SOP
or TSSOP package and is specified over the -40°C
to +85°C temperature range.
Features
• 2.7V to 5.5V Input Voltage Range
• 80mΩ (5V) Typical R
DS(ON)
• Low Quiescent Current: 15µA (Typ)
• Reverse-Blocking Switches
• Short-Circuit Protection
• Over-Temperature Protection
• FAULT Flag Output
• Temperature Range: -40°C to +85°C
• 8-Pin SOP or TSSOP Package
Applications
• Notebook Computer
• PDA, Subnotebook
• Power Supply Multiplexer Circuit
Typical Application
C
OUT
0. 1 µ F
VCC5
C
IN5
1 µ F
C
IN3
1 µ F
VCC3
VCCD1
VCCD0
F AUL T
VCC
GND
AAT4651
8
5
2
3
4
1
6,7
VCC3
VCC5
GND G ND
VCC
VCCD1
VCCD0
FAULT