AAT4626_08 Datasheet, PDF (7/15 Pages) Advanced Analogic Technologies – USB Dual-Channel Power Switch

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Functional Block Diagram
IN
Over-
Temperature
Protection
Under-
Voltage
Lockout
PRODUCT DATASHEET
AAT4626
USB Dual-Channel Power Switch
OUTA
OUTB
ENA (ENA)
1.2V
Reference
Current
Limit
Over-Temp Protection
Under-Voltage Lockout
Current Limit
Over-Temp Protection
Under-Voltage Lockout
Current Limit
ENB (ENB)
FLGA
FLGB
Functional Description
The AAT4626 is a dual integrated MOSFET load switch
with a fixed level current limit, over-temperature protec-
tion, level shifted inputs, and a fault flag for each switch.
The current limit control is combined with an over-tem-
perature thermal limit circuit to provide a comprehensive
system to protect the load switch under short-circuit or
other adverse operating conditions. The AAT4626 is ide-
ally suited 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 activated when
the output load current exceeds a preset internal thresh-
old level. The minimum current limit threshold character-
istic is specified by I_LIM(MIN). If the load switch ambient
temperature becomes excessive or if a short-circuit con-
dition persists, the die temperature will rise, causing the
over-temperature protection circuit to activate.
If the current limit or over-temperature protection cir-
cuits are active for more than ten milliseconds, the sys-
tem will be informed via the FAULT flag. The ten millisec-
ond 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 con-
nected directly to system controllers driven by voltage
levels 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 typi-
cally consumes 20μA when operating; when off, the
device draws less than 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.
4626.2008.02.1.3
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