AAT4610A_07 Datasheet, PDF (8/11 Pages) Advanced Analogic Technologies – Current Limited Load Switch

Functional Block Diagram
AAT4610A
Current Limited Load Switch
IN
Under-
Voltage
Lockout
Over-Temperature
Protection
OUT
ON (ON)
1.2V
Reference
GND
Current
Limit
SET
R_SET
Application Information
Setting Current Limit
In most applications, the variation in I_LIM must be
taken into account when determining R_SET. The I_LIM
variation is due to processing variations from part
to part, as well as variations in the voltages at IN
and OUT, plus the operating temperature. See
charts "Current Limit vs. Temperature" and "Output
Current vs. V_OUT." Together, these three factors
add up to a ±25% tolerance (see I_LIM specification
in Electrical Characteristics section). Figure 1 illus-
trates a cold device with a statistically higher cur-
rent limit and a hot device with a statistically lower
current limit, both with R_SET equal to 10.5kΩ. While
the chart, "R_SET vs. I_LIM" indicates an I_LIM of 0.7A
with an R_SET of 10.5kΩ, this figure shows that the
actual current limit will be at least 0.525A and no
greater than 0.880A.
8
Ω
1.2
1
0.88A
Device with high current limit at -40°C
0.8
0.6
0.4
0.525A
0.2
Device with low current limit at 85°C
0
0
1
2
3
4
5
V_OUT (V)
Figure 1: Current Limit Using 10.5kΩ.
To determine R_SET, start with the maximum current
drawn by the load and multiply it by 1.33 (typical
I_LIM = minimum I_LIM / 0.75). This is the typical cur-
rent limit value. Next, refer to "R_SET vs. I_LIM" and
find the R_SET that corresponds to the typical current
limit value. Choose the largest resistor available
that is less than or equal to it. For greater precision,
the value of R_SET may also be calculated using the
4610A.2007.06.1.4