AAT4650_06 ANALOGICTECH [Advanced Analogic Technologies], AAT4650_06 Datasheet - Page 8

• Manufacturer Part Number: AAT4650_06
• Description: 5V/3V PC Card Power Switch
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

Applications Information
Input Capacitor
A 1µF or larger capacitor is typically recommended
for C
operation; however, it is useful in preventing load
transients from affecting up-stream circuits.
should be located as close to the device VIN pin as
practically possible.
minum electrolytic capacitors may be selected for
C
resistance (ESR) requirement for C
higher current operation, ceramic capacitors are rec-
ommended for C
over tantalum capacitors to withstand input current
surges from low impedance sources such as batter-
ies in portable devices.
Output Capacitor
A 0.1µF or greater capacitor is generally required
between V
capacitor, there is no specific capacitor ESR
requirement. If desired, C
accommodate any load transient condition.
Parallel Interface / Break Before Make
A 2-bit parallel interface determines the state of the
V
CMOS or TTL logic. A logic low value must be less
than 0.8V, and a logic high value must be greater
than 2.4V. In cases where the interface pins rapidly
change state directly from 3V to 5V (or vice versa),
internal break-before-make circuitry prevents any
back flow of current from one input power supply to
the other. In addition, the body connections of the
internal P-channel MOSFET switches are always
set to the highest potential of V
which prevents any body diode conduction, power
supply backflow, or possible device damage.
FAULT Output
The FAULT output is pulled to ground by an open
drain N-channel MOSFET during an over-current
or output slew condition. It should be pulled up to
the reference power supply of the controller IC via
a nominal 100kΩ resistor.
8
CC
IN
. There is no specific capacitor equivalent series
output. The logic levels are compatible with
IN
. A C
CC
IN
and GND. Likewise, with the output
capacitor is not required for basic
IN
due to their inherent capability
Ceramic, tantalum, or alu-
OUT
may be increased to
CC3
IN
, V
. However, for
CC5
, or V
C
CC
IN
,
Voltage Regulation
The PC card specification calls for a regulated 5V
supply tolerance of ±5%. Of this, a typical power
supply will drop less than 2% and the PCB traces
will drop another 1%.
AAT4650 as the PC card switch. In the PC card
application, the maximum allowable current for the
AAT4650 is dominated by voltage regulation, rather
than by thermal considerations, and is set by either
the current limit or the maximum R
channel MOSFET. The maximum R
is calculated by applying the R
ficient to the maximum room temperature R
-or-
The maximum current is equal to the 2% tolerance
of the 5V supply (100mV) across the AAT4650
divided by R
For the 3.3V supply in the PC card application, the
conditions are a bit relaxed, with the allowable volt-
age regulation drop equal to 300mV. With a 2%
supply and 1% PCB trace regulation, the PC card
switch can have a 200mV drop. So:
Since 1.5A is the nominal current limit value, the
AAT4650 will current limit before I
R
DS(ON)(MAX)
5V/3V PC Card Power Switch
R
DS(ON)(MAX)
I
= 100mΩ ⋅ (1 + [0.0028 ⋅ 60]) = 116.8mΩ
MAX5
DS(ON)(MAX)
I
MAX3
=
116.8mΩ
=
= R
100mV
134mΩ
200mV
DS(ON)25
. Or:
This leaves 2% for the
= 856.2mA
⋅ (1 + [TC ⋅ ΔT])
= 1.5A
DS
temperature coef-
AAT4650
MAX3
DS(ON)
DS(ON)
4650.2006.05.1.2
is reached.
of the P-
at 85°C
DS(ON)
: