AAT4611_06 ANALOGICTECH [Advanced Analogic Technologies], AAT4611_06 Datasheet - Page 9

• Manufacturer Part Number: AAT4611_06
• Description: Current Limited Load Switch in SOT23 Package
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

I
the typical current for the chosen R
by 1.25. Some standard resistor values are listed in
Table 1.
Example: A USB port requires 0.5A. 0.5A multiplied
by 1.33 is 0.665A. From the chart "R
R
dard value that is slightly less than, but very close
to, 11kΩ. The chart gives approximately 0.7A as a
4611.2006.09.1.4
LIM
R
(kΩ Ω )
SET
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
SET
." The maximum current is derived by multiplying
should be less than 11kΩ. 10.5 kΩ is a stan-
Table 1: Current Limit R
Current
Limit
(Typ)
(mA)
1000
1200
1300
1400
1100
200
250
300
350
400
450
500
550
600
700
800
900
4
3
2
1
0
5
-0.05
Limit Below
Not Current Current Limits
Device Will
(mA)
1050
150
188
225
263
300
338
375
413
450
525
600
675
750
825
900
975
0
1Ω Load is Turned On at Time = 0
SET
Device Always
SET
Values.
SET
Below
0.05
Figure 2: Overload Operation.
in the chart
(mA)
1000
1250
1375
1500
1625
1750
1125
Current Limited Load Switch in SOT23 Package
250
313
375
438
500
563
625
688
750
875
vs. I
LIM
,"
0.1
Time (s)
typical I
0.75 and 1.25 shows that the AAT4611 will limit the
load current to greater than 0.525A but less than
0.875A.
Operation in Current Limit
When a heavy load is applied to the output of the
AAT4611, the load current is limited to the value of
I
load is demanding more current than I
age at the output drops. This causes the AAT4611 to
dissipate a larger-than-normal quantity of power,
and causes the die temperature to increase. When
the die temperature exceeds an over-temperature
limit, the AAT4611 will shut down until is has cooled
sufficiently, at which point it will start up again. The
AAT4611 will continue to cycle on and off until the
load is removed, power is removed, or until a logic
high level is applied to ON (Pin 4).
Enable Input
In many systems, power planes are controlled by
integrated circuits which run at lower voltages than
the power plane itself. The enable input ON (Pin 4) of
the AAT4611 has low and high threshold voltages that
accommodate this condition. The threshold voltages
are compatible with 5V TTL and 2.5V to 5V CMOS.
Reverse Voltage
The AAT4611 is designed to control current flowing
from IN to OUT. If a voltage is applied to OUT which
is greater than the voltage on IN, large currents may
flow. This could cause damage to the AAT4611.
0.15
LIM
determined by R
Output Current
Output Voltage
LIM
0.2
value for 10.5kΩ. Multiplying 0.7A by
0.25
SET
(see Figure 2). Since the
0.3
1
0.75
0.5
0.25
0
AAT4611
LIM
, the volt-
9