AAT4601 Datasheet, PDF (8/16 Pages) Advanced Analogic Technologies – 1.5A Current Limited P-Channel Switch

Functional Block Diagram
AAT4601
1.8A Current Limited P-Channel Switch
IN
Under-
Voltage
Lockout
Over-Temperature
Protection
ON
1.2V
Reference
Current
Limit
OUT
FAULT
SET
Functional Description
The AAT4601 is an integrated MOSFET load switch
with an adjustable current limit, over-temperature
protection, level-shifted input, and a fault flag. The
current limit control is combined with an over-tem-
perature thermal limit circuit to provide a compre-
hensive system to protect the load switch under
short-circuit or other adverse operating conditions.
The AAT4601 is ideally suited for control and pro-
tection 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 an
internal threshold level. The internal current limit
threshold is determined by an external resistor
connected between the SET pin and ground. The
minimum current limit threshold 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-temperature protection circuit to activate.
If a current limit level less than I_LIM(MIN) is required,
the AAT4601 can be used to operate in foldback
8
current limit mode. To achieve this, an R_SET value
can be chosen to program a current limit lower
than I_LIM(MIN); in this case, when the load current
reaches I_LIM(MIN), the current will immediately drop,
limiting at the programmed value.
If the current limit or over-temperature protection
circuits are active for more than 2ms, the system
will be informed via the FAULT flag. The 2ms delay
allows the AAT4601 to be turned on into capacitive
loads without activating the FAULT flag. The open
drain FAULT output can be connected directly to
system controllers driven by voltage levels less
than the IN pin voltage without additional level
shifting circuitry.
The load switch is turned off by applying a logic high
level to the ON pin. The AAT4601 typically con-
sumes 12µA when operating; when off, the device
draws less than 1µA. In the off state, current is pre-
vented from flowing between the input and output.
The ON function has logic level thresholds that
allow the AAT4601 to be TTL compatible and may
also be controlled by 2.5V to 5.0V CMOS circuits.
The voltage level on either ON or FAULT should not
exceed the input supply level present on the IN pin.
4601.2006.05.1.3