AAT4626 Datasheet, PDF (6/14 Pages) Advanced Analogic Technologies – USB Dual-Channel Power Switch

Functional Block Diagram
AAT4626
USB Dual-Channel Power Switch
IN
Over-Temp
Protection
Under-
Voltage
Lockout
OUT A
OUT B
EN A (EN A)
1.2V
Reference
Current
Limit
Over-Temp Protection
Under-Voltage Lockout
Current Limit
Over-Temp Protection
Under-Voltage Lockout
Current Limit
EN B (EN B)
FLG A
FLG B
Functional Description
The AAT4626 is a dual integrated MOSFET load
switch with a fixed level current limit, over temper-
ature protection, level shifted inputs and a fault flag
for each switch. The current limit control is com-
bined with an over temperature thermal limit circuit
to provide a comprehensive system to protect the
load switch under short circuit or other adverse
operating conditions. The AAT4626 is ideally suit-
ed for control and protection of peripheral ports
such as USB, RS232 and parallel ports.
The current limit and over temperature circuits will
act independently. The device current limit is acti-
vated when the output load current exceeds a pre-
set internal threshold level. The minimum current
limit threshold characteristic is specified by I_LIM(MIN).
If the load switch ambient temperature becomes
excessive or if a short circuit condition persists, the
die temperature will rise causing the over tempera-
ture protection circuit to activate.
If the current limit or over temperature protection
circuits are active for more then ten milliseconds,
6
the system will be informed via the FAULT Flag.
The ten millisecond fault blanking delay allows the
AAT4626 to be turned on into large capacitive
loads without activating the FAULT Flags. The
open drain FAULT outputs can be connected
directly to system controllers driven by voltage lev-
els less than the IN pin voltage without additional
level shifting circuitry.
Each of the two load switches is turned on and off
by applying a logic level signal to the EN(A/B) pin.
The AAT4626 enable function is available in both
active high and active low logic level versions. The
AAT4626 typically consumes 20µA when operat-
ing, when off, the device draws less then 1µA. In
the off state, current is prevented from flowing
between the input and output on each respective
channel. The EN(A/B) function has logic level
thresholds that allow the AAT4626 to be TTL com-
patible and may also be controlled by 2.5V to 5.0V
CMOS circuits. The voltage level on either
EN(A/B) or FAULT(A/B) should not exceed the
input supply level present on the IN pin.
4626.2002.1.0.93