AAT3236IGV-2.8-T1 AAT [Advanced Analog Technology, Inc.], AAT3236IGV-2.8-T1 Datasheet - Page 12

• Manufacturer Part Number: AAT3236IGV-2.8-T1
• Description: 300mA CMOS High Performance LDO
• Manufacturer: AAT [Advanced Analog Technology, Inc.]

From the discussion above, P
mined to equal 526mW at T
Thus, the AAT3236 can sustain a constant 3V output
at a 500mA load current as long as V
an ambient temperature of 25°C.
Higher input-to-output voltage differentials can be
obtained with the AAT3236, 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
while V
V
safe continuous input level for V
500mA for T
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
12
V
%DC = 100
%DC = 100
V
I
I
V
I
I
V
V
%DC = 87.57%
OUT
GND
GND
OUT
IN
D(MAX)
OUT
IN(MAX)
IN(MAX)
IN
OUT
is greater than 4.05V, which is the maximum
= 3.0V
= 150μA
= 500mA
= 4.2V
OUT
is assumed to be 526mW.
=
= 4.05V
= 3.0V
= 500mA
= 150μA
526mW + (3.0V × 500mA)
= 3.0V at a 500mA load and T
A
(4.2V - 3.0V)500mA + (4.2V × 150μA)
(V
= 25°C. To maintain this high input
500mA + 150μA
IN
- V
OUT
)I
P
OUT
D(MAX)
A
+ (V
526mW
= 25°C.
IN
D(MAX)
× I
OUT
IN
GND
is ≤ 4.05V at
was deter-
)
= 3.0V at
IN
A
= 25°C.
= 4.2V
300mA CMOS High Performance LDO
For a 500mA output current and a 1.2 volt drop
across the AAT3236 at an ambient temperature of
25°C, the maximum on-time duty cycle for the
device would be 87.57%.
The following family of curves show the safe oper-
ating area for duty-cycled operation from ambient
room temperature to the maximum operating level.
3.5
2.5
1.5
0.5
3.5
2.5
1.5
0.5
3.5
2.5
1.5
0.5
3
2
1
0
3
2
1
0
3
2
1
0
0
0
0
500 mA
500 mA
10
10
10
400 mA
Device Duty Cycle vs. V
500 mA
Device Duty Cycle vs. V
400 mA
Device Duty Cycle vs. V
20
20
20
400 mA
(V
30
(V
30
30
300 mA
OUT
(V
OUT
Duty Cycle (%)
Duty Cycle (%)
OUT
300 mA
Duty Cycle (%)
= 2.5V @ 25°C)
40
40
40
= 2.5V @ 50°C)
= 2.5V @ 85°C)
300 mA
50
50
50
60
60
200 mA
60
200 mA
AAT3236
70
70
70
DROP
DROP
3236.2007.03.1.4
DROP
80
80
80
100 mA
200 mA
100 mA
90
90
90
100
100
100