AAT3242 AAT, AAT3242 Datasheet - Page 13

• Manufacturer Part Number: AAT3242
• Description: Dual CMOS LDO Linear Regulator
• Manufacturer: AAT

The following is an example for a 2.5V output:
V
V
I
From the discussion above, P
Therefore, with Regulator B delivering 150mA at 1.5V, Regulator A can sustain a constant 2.5V output at a
296mA load current at an ambient temperature of 25°C. Higher input-to-output voltage differentials can be
obtained with the AAT3242, 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 oper-
ating the LDO regulator in a duty-cycled mode.
For example, an application requires V
tain 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:
I
I
P
For a 500mA output current and a 2.7V drop across the AAT3242 at an ambient temperature of 25°C, the max-
imum on-time duty cycle for the device would be 48.10%.
I
%DC =
%DC =
3242.2006.04.1.10
V
I
I
V
V
%DC = 48.10%
OUTB
GND
OUT
OUTA(MAX)
GND
OUTA(MAX)
OUTA
OUTB
D(MAX)
IN
IN
OUT
= 125µA
= 500mA
= 4.2V
= 1.5V
is assumed to be 909mW
[(V
[(4.2V - 1.5V)500mA + (4.2V × 125μA)] + [(4.2V - 1.5V)200mA + (4.2V × 125μA)]
= 2.5V
= 1.5V
= 150mA
= 4.2V
= 125μA
=
= 296mA
IN
909mW - (2 × 4.2V × 125μA) - (4.2 - 1.5) × 150mA
- V
OUTA
)I
OUTA
+ (V
IN
D(MAX)
100(P
4.2 - 2.5
× I
GND
was determined to equal 909mW at T
D(MAX)
)] + [(V
IN
300mA/150mA Dual CMOS LDO Linear Regulator
100(909mW)
)
= 4.2V while V
IN
- V
OUTB
)I
OUTB
OUT
+ (V
= 1.5V at a 500mA load and T
IN
× I
GND
)]
A
= 25°C.
A
AAT3242
= 25°C. To main-
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