AAT3218 Datasheet, PDF (12/18 Pages) List of Unclassifed Manufacturers – 150mA MicroPower™ High Performance LDO

AAT3218
150mA MicroPower™ High Performance LDO
Applications Information
V_OUT = 2.5 volts
I_OUT = 150mA
I_GND = 150uA
V_IN(MAX)=(211mW+(2.5Vx150mA))/(150mA +150uA)
V_IN(MAX) = 3.90V
Higher input to output voltage differentials can be
obtained with the AAT3218, while maintaining
device functions within the thermal safe operating
area. To accomplish this, the device thermal
resistance must be reduced by increasing the heat
sink area or by operating the LDO regulator in a
duty cycled mode.
For example, an application requires V_IN = 4.2V
while V_OUT = 2.5V at a 150mA load and T_A = 85°C.
V_IN is greater than 3.90V, which is the maximum
safe continuous input level for V_OUT = 2.5V at
150mA for T_A = 85°C. To maintain this high input
voltage and output current level, the LDO regulator
must be operated in a duty cycled mode. Refer to
the following calculation for duty cycle operation:
P_D(MAX) is assumed to be 211mW
I_GND = 150µA
I_OUT = 150mA
V_IN = 4.2 volts
V_OUT = 2.5 volt
%DC=100(P_D(MAX)/((V_IN-V_OUT)I_OUT+(V_INxI_GND))
%DC=100(211mW/((4.2V-2.5V)150mA+(4.2Vx150µA))
%DC = 85.54%
For a 150mA output current and a 2.7volt drop
across the AAT3218 at an ambient temperature of
85°C, the maximum on time duty cycle for the
device would be 85.54%.
The following family of curves show the safe oper-
ating area for duty cycled operation from ambient
room temperature to the maximum operating level.
Device Duty Cycle vs. V_DROP
V_OUT = 2.5V @ 25 C
3.5
3
2.5
2
1.5
1
0.5
0
0
200mA
10 20 30 40 50 60 70 80 90 100
Duty Cycle (%)
Device Duty Cycle vs. V_DROP
V_OUT= 2.5V @ 50 C
3.5
3
2.5
2
1.5
1
0.5
0
0
200mA
150mA
10 20 30 40 50 60 70 80 90 100
Duty Cycle (%)
Device Duty Cycle vs.
V_OUT = 2.5V @ 85 C
V_DROP
3.5
3
2.5
2
1.5
1
0.5
0
0
200mA
150mA
100mA
10 20 30 40 50 60 70 80 90 100
Duty Cycle (%)
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