aat3223igu-3.0-t1 Advanced Analogic Technologies, Inc., aat3223igu-3.0-t1 Datasheet - Page 13

• Manufacturer Part Number: aat3223igu-3.0-t1
• Description: Aat3223 | 250ma Nanopower Ldo Linear Regulator With Power Ok
• Manufacturer: Advanced Analogic Technologies, Inc.

The following is an example for an AAT3223 set for
a 2.8V output:
From the discussion above, P
mined to equal 667mW at T
Thus, the AAT3223 can sustain a constant 2.8V
output at a 150mA load current as long as V
≤9.11V at an ambient temperature of 25°C. 5.5V
is the maximum input operating voltage for the
AAT3223, thus at 25°C, the device would not
have any thermal concerns or operational V
limits.
This situation can be different at 85°C. The follow-
ing is an example for an AAT3223 set for a 2.8V
output at 85°C:
From the discussion above, P
mined to equal 267mW at T
3223.2006.03.1.5
V
I
I
V
V
V
I
I
V
V
OUT
GND
OUT
GND
OUT
IN(MAX)
IN(MAX)
OUT
IN(MAX)
IN(MAX)
= 2.9V
= 250mA
= 1.1µA
=
= 9.11V
= 2.9V
= 150mA
= 1.1µA
=
= 4.58V
667mW + (2.8V × 150mA)
267mW + (2.8V × 150mA)
150mA + 1.1µA
150mA + 1.1µA
A
A
= 25°C.
= 85°C.
D(MAX)
D(MAX)
was deter-
was deter-
IN(MAX)
IN
is
Higher input-to-output voltage differentials can be
obtained with the AAT3223, while maintaining
device functions in 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
150mA for T
voltage and output current level, the LDO regula-
tor must be operated in a duty-cycled mode.
Refer to the following calculation for duty-cycle
operation:
P
For a 150mA output current and a 2.2V drop across
the AAT3223 at an ambient temperature of 85°C,
the maximum on-time duty cycle for the device
would be 80.9%.
The following family of curves shows the safe
operating area for duty-cycled operation from
ambient room temperature to the maximum oper-
ating level.
I
I
V
V
%DC = 100
%DC = 100
%DC = 80.9%
GND
OUT
IN
D(MAX)
Linear Regulator with Power-OK
IN
OUT
is greater than 4.58V, which is the maximum
= 1.1µA
= 150mA
= 5.0V
= 2.8V
OUT
was assumed to be 267mW.
250mA NanoPower™ LDO
= 2.8V at a 150mA load and T
A
(5.0V - 2.8V)150mA + (5.0V × 1.1µA)
(V
= 85°C. To maintain this high input
IN
- V
OUT
)I
P
OUT
D(MAX)
+ (V
267mW
IN
AAT3223
× I
OUT
GND
)
= 2.8V at
IN
A
= 85°C.
= 5.0V
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