AAT4610
Current Limited Load Switch in SOT-23 Package
that is less than or equal to it. For greater precision,
the value of RSET may also be calculated using the
ILIM RSET product found in the chart "RSET coeffi-
cient vs. ILIM". The maximum current is derived by
multiplying the typical current for the chosen RSET
in the chart by 1.25. A few standard resistor values
are listed in the table "Current Limit RSET Values".
Applications Information
Setting Current Limit
In most applications, the variation in ILIM must be
taken into account when determining RSET. The ILIM
variation is due to processing variations from part
to part, as well as variations in the voltages at IN
(pin 5) and OUT (pin 3), plus the operating temper-
ature. See charts "Current Limit vs. Temperature",
and "Output Current vs. VOUT". Together these
three factors add up to a 25% tolerance (see ILIM
specification in Electrical Characteristics section).
In the figure below, a cold device with a statistical-
ly higher current limit, and a hot device with a sta-
tistically lower current limit, both with RSET equal to
Current Limit RSET Values
RSET
Current Device will
Limit typ not current
Device always
current limits
below:
(mA)
250
(kΩ)
(mA)
limit below:
(mA)
150
40.2
30.9
24.9
22.1
19.6
17.8
16.2
14.7
13.0
10.5
8.87
7.50
6.81
6.04
5.49
4.99
4.64
200
250
188
313
375
438
500
563
625
688
750
10.5kΩ are shown. While the chart, "R
vs. ILIM"
SET
300
225
indicates an ILIM of 0.7A with an RSET of 10.5kΩ ,
this figure shows that the actual current limit will be
at least 0.525A, and no greater than 0.880A.
350
263
400
300
450
338
500
375
Current Limit Using10.5 k
Ω
550
413
600
450
1.2
1
700
525
875
Device with high current limit at -40 C
0.88 A
800
600
1000
1125
1250
1375
1500
1625
1750
900
675
0.8
0.6
0.4
0.2
0
1000
1100
1200
1300
1400
750
825
900
975
0.525 A
Device with low current limit at 85 C
1050
Example: A USB port requires 0.5A. 0.5A multiplied
by 1.33 is 0.665A. From the chart named "RSET vs.
ILIM", RSET should be less than 11kΩ. 10.5 kΩ is a
standard value that is a little less than 11kΩ but
very close. The chart reads approximately 0.700A
as a typical ILIM value for 10.5kΩ . Multiplying
0.700A by 0.75 and 1.25 shows that the AAT4610
will limit the load current to greater than 0.525A but
less than 0.875A.
0
1
2
3
4
5
Vout (V)
To determine RSET, start with the maximum current
drawn by the load, and multiply it by 1.33. (typi-
cal_ILIM = minimum_ILIM / 0.75) This is the typical
current limit value. Next, refer to "RSET vs. ILIM" and
find the RSET that corresponds to the typical current
limit value. Choose the largest resistor available
8
4610.2001.9.0.97