AAT4610 Datasheet, PDF (8/10 Pages) Advanced Analogic Technologies – Current Limited Load Switch in SOT-23 Package

Functional Block Diagram
AAT4610
Current Limited Load Switch
IN
Under-
Voltage
Lockout
Over-Temperature
Protection
OUT
ON (ON)
1.2V
Reference
GND
Current
Limit
SET
R_SET
Applications 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
(Pin 5) and OUT (Pin 1), plus the operating tem-
perature. See the charts "Current Limit vs.
Temperature" and "Output Current vs. V_OUT" in the
Typical Characteristics section of this datasheet.
Together, these three factors add up to a ±25% tol-
erance (see I_LIM specification in the Electrical
Characteristics section of this datasheet). Figure 1
shows 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.
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: Output Current Using 10.5kΩ.
To determine R_SET, start with the maximum current
drawn by the load, and multiply it by 1.33 (typi-
cal_I_LIM = minimum_I_LIM / 0.75). This is the typical
current 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,
8
Not recommended for new designs; pin-for-pin upgrade: AAT4610A.
4610.2006.09.1.3